metformin (Rx)

Brand and Other Names:Glucophage, Glucophage XR, more...Glumetza, Riomet, Riomet ER
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Dosing & Uses

AdultPediatricGeriatric

Dosage Forms & Strengths

tablet, immediate-release

  • 500mg (generic)
  • 850mg (generic)
  • 1000mg (generic)

tablet, extended-release

  • 500mg (generic, Glumetza)
  • 750mg (generic)

1000mg (generic, Glumetza)

oral solution

  • 100mg/mL (Riomet)

oral suspension, extended-release

  • 47.31g/473mL per bottle (Riomet ER)
  • Reconstituted suspension is 500mg/5mL

Type 2 Diabetes Mellitus

Adjunctive therapy to diet and exercise to improve glycemic control in adults with type 2 diabetes

Monotherapy or with sulfonylurea

Immediate-release tablet or solution

  • Initial: 500 mg PO q12hr or 850 mg PO qDay with meals; increase dose in increments of 500 mg/week or 850 mg q2Weeks on the basis of glycemic control and tolerability
  • Maintenance: 1500-2550 mg/day PO divided q8-12hr with meal
  • Not to exceed 2550 mg/day

Extended-release tablet or suspension

  • 500 mg PO qDay with dinner; titrate by 500 mg/day qWeek; not to exceed 2000 mg/day

Type 2 Diabetes Prevention (Off-label)

850 mg PO qDay

Target dosing: 850 mg PO q12hr

Dosage Modifications

Hepatic impairment: Avoid use; risk of lactic acidosis

Renal impairment

  • Obtain eGFR before starting metformin
  • eGFR <30 mL/min/1.73 m²: Contraindicated
  • eGFR 30-45 mL/min/1.73 m²: Not recommended to initiate treatment
  • Monitor eGFR at least annually or more often for those at risk for renal impairment (eg, elderly)
  • If eGFR falls below 45mL/min/1.73 m² while taking metformin, risks and benefits of continuing therapy should be evaluated
  • If eGFR falls below 30 mL/min/1.73 m² while taking metformin, discontinue drug

Discontinuation for iodinated contrast imaging procedures

  • Discontinue metformin HCl at the time of, or prior to, an iodinated contrast imaging procedure in patients with an eGFR between 30 and 60 mL/min/1.73 m2 ; in patients with a history of liver disease, alcoholism, or heart failure; or in patients who will be administered intra-arterial iodinated contrast
  • Re-evaluate eGFR 48 hr after imaging procedure; restart metformin HCl if renal function is stable

Dosing Consideration

Switching from metformin immediate-release to metformin extended-release

  • Patients receiving metformin HCl may be switched to metformin extended-release at the same total daily dose, up to 2,000 mg/day

Polycystic Ovary Syndrome (Orphan)

Orphan designation for treatment of pediatric polycystic ovary syndrome

Sponsor

  • EffRx Pharmaceuticals SA; Wolleraustrass 41 B; 8807 Freienbach (SZ); SWITZERLAND

Myoclonus Epilepsy (Orphan)

Orphan designation for treatment of progressive myoclonus epilepsy type 2 (Lafora disease)

Sponsor

  • Consorcio Centro de Investigación Biomédica en Red, M.P. (CIBER); Monforte de Lemos, 3-5 Pabellon 11; Madrid, Spain

Dosage Forms & Strengths

tablet, immediate-release

  • 500mg (generic)
  • 850mg (generic)
  • 1000mg (generic)

oral solution

  • 100mg/mL (Riomet)

oral suspension, extended-release

  • 47.31g/473mL per bottle (Riomet ER)
  • Reconstituted suspension is 500mg/5mL

Type 2 Diabetes Mellitus

Indicated as an adjunct to diet and exercise to improve glycemic control in adults and pediatric patients (≥10 years) with type 2 diabetes mellitus.

10 to <17 years

  • Immediate-release
    • Initial: 500 mg PO q12hr
    • Maintenance: Titrate qWeek by 500 mg; no more than 2000 mg/day in divided doses
  • Extended-release
    • 500 mg PO qDay with dinner; increase the dose in increments of 500 mg (5 mL) weekly, up to a maximum dose of 2,000 mg (20 mL) once daily, with the evening meal

Dosage Modifications

Renal impairment

  • Obtain eGFR before initiating metformin
  • eGFR <30 mL/min/1.73 m²: Contraindicated
  • eGFR 30-45 mL/min/1.73 m²: Initiating not recommended
  • Obtain GFR at least annually in all patients taking metformin; assess eGFR more frequently in patients at increased risk for renal impairment (eg, elderly)
  • If eGFR falls to <45 mL/min/1.73 m² during treatment: Assess the benefits and risks of continuing treatment
  • If eGFR falls to <30 mL/min/1.73 m² during treatment: Discontinue

Elderly patients are more likely to have decreased renal function; contraindicated in patients with renal impairment, carefully monitor renal function in the elderly and use with caution as age increases

Not for use in patients >80 years unless normal renal function establishedInitial and maintenance dosing of metformin should be conservative in patients with advanced age due to the potential for decreased renal function in this population

Controlled clinical studies of metformin did not include sufficient numbers of elderly patients to determine whether they respond differently from younger patients

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Interactions

Interaction Checker

and metformin

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              Serious - Use Alternative (12)

              • contrast media (iodinated)

                contrast media (iodinated) increases levels of metformin by decreasing renal clearance. Contraindicated. Acute renal failure or lactic acidosis may result. D/c metformin 48 hr before and after imaging study.

              • ethanol

                ethanol increases toxicity of metformin by Other (see comment). Contraindicated. Comment: Excessive EtOH consumption may alter glycemic control. Some sulfonylureas may produce a disulfiram like rxn; alcohol may potentiate the risk of lactic acidosis.

              • ioversol

                ioversol increases levels of metformin by decreasing renal clearance. Contraindicated. Acute renal failure or lactic acidosis may result. D/c metformin 48 hr before and after imaging study.

              • methylene blue

                methylene blue will increase the level or effect of metformin by unspecified interaction mechanism. Avoid or Use Alternate Drug.

              • ranolazine

                ranolazine will increase the level or effect of metformin by decreasing elimination. Avoid or Use Alternate Drug. Limit metformin dose to 1700 mg/day when used together with ranolazine 1000 mg twice daily; monitor closelly for signs or symptoms of metformin toxicity

              • risdiplam

                risdiplam will increase the level or effect of metformin by decreasing elimination. Avoid or Use Alternate Drug. Risdiplam inhibits MATE1 and MATE2-K. If unable to avoid coadministration with MATE substrates, consider dosage reduction of MATE substrate.

              • selegiline

                selegiline will increase the level or effect of metformin by unspecified interaction mechanism. Avoid or Use Alternate Drug.

              • selegiline transdermal

                selegiline transdermal will increase the level or effect of metformin by unspecified interaction mechanism. Avoid or Use Alternate Drug.

              • tafenoquine

                tafenoquine will increase the level or effect of metformin by Other (see comment). Avoid or Use Alternate Drug. Tafenoquine inhibits organic cation transporter-2 (OCT2) and multidrug and toxin extrusion (MATE) transporters in vitro. Avoid coadministration with OCT2 or MATE substrates. If coadministration cannot be avoided, monitor for substrate-related toxicities and consider dosage reduction if needed based on product labeling of the coadministered drug.

              • tedizolid

                tedizolid will increase the level or effect of metformin by unspecified interaction mechanism. Avoid or Use Alternate Drug.

              • tranylcypromine

                tranylcypromine will increase the level or effect of metformin by unspecified interaction mechanism. Avoid or Use Alternate Drug.

              • trilaciclib

                trilaciclib will decrease the level or effect of metformin by Other (see comment). Avoid or Use Alternate Drug. Avoid coadministration of trilaciclib (OCT2, MATE1, and MATE-2K inhibitor) with substrates where minimal increased concentration in kidney or blood may lead to serious or life-threatening toxicities.

              Monitor Closely (193)

              • acetazolamide

                acetazolamide increases toxicity of metformin by Other (see comment). Use Caution/Monitor. Comment: Decreases serum bicarbonate and induce non-anion gap, hyperchloremic metabolic acidosis.

              • albiglutide

                albiglutide, metformin. Either increases effects of the other by pharmacodynamic synergism. Use Caution/Monitor. Concurrent use may increase risk of hypoglycemia; monitor glucose levels.

              • amiodarone

                amiodarone will increase the level or effect of metformin by basic (cationic) drug competition for renal tubular clearance. Use Caution/Monitor.

              • amlodipine

                amlodipine decreases effects of metformin by pharmacodynamic antagonism. Use Caution/Monitor. Patient should be closely observed for loss of blood glucose control; when drugs are withdrawn from a patient receiving metformin, patient should be observed closely for hypoglycemia.

              • aripiprazole

                aripiprazole, metformin. Other (see comment). Use Caution/Monitor. Comment: Atypical antipsychotics have been associated with hyperglycemia that may alter blood glucose control; monitor glucose levels closely.

              • asenapine

                asenapine, metformin. Other (see comment). Use Caution/Monitor. Comment: Atypical antipsychotics have been associated with hyperglycemia that may alter blood glucose control; monitor glucose levels closely.

              • atazanavir

                atazanavir decreases effects of metformin by Other (see comment). Use Caution/Monitor. Comment: Reports of hyperglycemia due to insulin resistance with protease inhibitors. .

              • benazepril

                benazepril increases toxicity of metformin by unspecified interaction mechanism. Use Caution/Monitor. Increases risk for hypoglycemia and lactic acidosis.

              • benzphetamine

                benzphetamine decreases effects of metformin by pharmacodynamic antagonism. Use Caution/Monitor. Patient should be closely observed for loss of blood glucose control; when drugs are withdrawn from a patient receiving metformin, patient should be observed closely for hypoglycemia.

              • betamethasone

                betamethasone decreases effects of metformin by pharmacodynamic antagonism. Use Caution/Monitor.

              • bictegravir

                bictegravir will increase the level or effect of metformin by decreasing renal clearance. Modify Therapy/Monitor Closely. Bictegravir inhibits organic cation transporter 2 (OCT2) and multidrug and toxin extrusion transporter 1 (MATE1) in vitro. Coadministration with OCT2 and MATE1 substrates may increase their plasma concentrations. Metformin dose reduction may be required.

              • bitter melon

                bitter melon increases effects of metformin by pharmacodynamic synergism. Use Caution/Monitor. Risk of hypoglycemia.

              • brexpiprazole

                brexpiprazole decreases effects of metformin by pharmacodynamic antagonism. Use Caution/Monitor.

              • bumetanide

                bumetanide decreases effects of metformin by pharmacodynamic antagonism. Use Caution/Monitor.

              • bupropion

                bupropion increases levels of metformin by Other (see comment). Use Caution/Monitor. Comment: Bupropion may inhibit OCT2 mediated renal excretion of metformin.

              • captopril

                captopril increases toxicity of metformin by unspecified interaction mechanism. Use Caution/Monitor. Increases risk for hypoglycemia and lactic acidosis.

              • cariprazine

                cariprazine decreases effects of metformin by pharmacodynamic antagonism. Use Caution/Monitor.

              • cephalexin

                cephalexin increases toxicity of metformin by decreasing renal clearance. Use Caution/Monitor. particularly in patients who may have other risk factors for metformin toxicity. .

              • ceritinib

                ceritinib decreases effects of metformin by pharmacodynamic antagonism. Use Caution/Monitor.

              • chlorpromazine

                chlorpromazine decreases effects of metformin by pharmacodynamic antagonism. Use Caution/Monitor. Patient should be closely observed for loss of blood glucose control; when drugs are withdrawn from a patient receiving metformin, patient should be observed closely for hypoglycemia.

              • cimetidine

                cimetidine will increase the level or effect of metformin by basic (cationic) drug competition for renal tubular clearance. Use Caution/Monitor.

              • cinnamon

                cinnamon increases effects of metformin by pharmacodynamic synergism. Use Caution/Monitor. Potential for hypoglycemia.

              • ciprofloxacin

                ciprofloxacin increases effects of metformin by pharmacodynamic synergism. Use Caution/Monitor. Hyper and hypoglycemia have been reported in patients treated concomitantly with quinolones and antidiabetic agents. Careful monitoring of blood glucose is recommended.

              • citalopram

                citalopram increases effects of metformin by pharmacodynamic synergism. Use Caution/Monitor.

              • clevidipine

                clevidipine decreases effects of metformin by pharmacodynamic antagonism. Use Caution/Monitor. Patient should be closely observed for loss of blood glucose control; when drugs are withdrawn from a patient receiving metformin, patient should be observed closely for hypoglycemia.

              • clozapine

                clozapine, metformin. Other (see comment). Use Caution/Monitor. Comment: Atypical antipsychotics have been associated with hyperglycemia that may alter blood glucose control; monitor glucose levels closely.

              • colesevelam

                colesevelam increases levels of metformin by pharmacodynamic antagonism. Use Caution/Monitor.

              • conjugated estrogens

                conjugated estrogens decreases effects of metformin by pharmacodynamic antagonism. Use Caution/Monitor.

              • corticotropin

                corticotropin decreases effects of metformin by pharmacodynamic antagonism. Use Caution/Monitor.

              • dabrafenib

                dabrafenib decreases effects of metformin by pharmacodynamic antagonism. Use Caution/Monitor.

              • dalfampridine

                metformin, dalfampridine. Either increases levels of the other by Other (see comment). Use Caution/Monitor. Comment: Metformin and dalfampridine are organic cation transporter 2 (OCT2) substrates; both drugs may compete for renal tubular uptake and could potentially increase systemic exposure of either drug when administered concomitantly.

              • darunavir

                darunavir decreases effects of metformin by Other (see comment). Use Caution/Monitor. Comment: Reports of hyperglycemia due to insulin resistance with protease inhibitors. .

              • desogestrel

                desogestrel decreases effects of metformin by pharmacodynamic antagonism. Use Caution/Monitor.

              • diatrizoate

                diatrizoate increases toxicity of metformin by unspecified interaction mechanism. Modify Therapy/Monitor Closely. Administration of intravascular iodinated contrast agents in metformin-treated patients has led to rare cases of acute decrease in renal function and the occurrence of lactic acidosis. The American College of Radiology Guidelines (2018) recommend temporarily stopping metformin in patients with eGFR is <30 mL/min/1.73 m2 or who are undergoing arterial catheter studies that might result in emboli to the renal arteries. Continue to withhold metformin for 48 hr subsequent to the procedure and reinstituted only after renal function has been reevaluated and found to be normal. .

              • diatrizoate meglumine/diatrizoate sodium

                diatrizoate meglumine/diatrizoate sodium increases toxicity of metformin by unspecified interaction mechanism. Modify Therapy/Monitor Closely. Administration of intravascular iodinated contrast agents in metformin-treated patients has led to rare cases of acute decrease in renal function and the occurrence of lactic acidosis. The American College of Radiology Guidelines (2018) recommend temporarily stopping metformin in patients with eGFR is <30 mL/min/1.73 m2 or who are undergoing arterial catheter studies that might result in emboli to the renal arteries. Continue to withhold metformin for 48 hr subsequent to the procedure and reinstituted only after renal function has been reevaluated and found to be normal. .

              • diazoxide

                diazoxide decreases effects of metformin by pharmacodynamic antagonism. Use Caution/Monitor.

              • dichlorphenamide

                dichlorphenamide, metformin. Either increases toxicity of the other by pharmacodynamic synergism. Modify Therapy/Monitor Closely. Both drugs can cause metabolic acidosis.

              • dienogest/estradiol valerate

                dienogest/estradiol valerate decreases effects of metformin by pharmacodynamic antagonism. Use Caution/Monitor.

              • diethylpropion

                diethylpropion decreases effects of metformin by pharmacodynamic antagonism. Use Caution/Monitor. Patient should be closely observed for loss of blood glucose control; when drugs are withdrawn from a patient receiving metformin, patient should be observed closely for hypoglycemia.

              • digoxin

                digoxin, metformin. Either increases levels of the other by basic (cationic) drug competition for renal tubular clearance. Use Caution/Monitor. Measure serum digoxin concentrations before initiating metformin. Monitor patients who take both metformin and digoxin for possible digoxin toxicity and lactic acidosis. Reduce the digoxin and/or metformin dose as necessary.

              • diltiazem

                diltiazem decreases effects of metformin by pharmacodynamic antagonism. Use Caution/Monitor. Patient should be closely observed for loss of blood glucose control; when drugs are withdrawn from a patient receiving metformin, patient should be observed closely for hypoglycemia.

              • dofetilide

                dofetilide will increase the level or effect of metformin by basic (cationic) drug competition for renal tubular clearance. Use Caution/Monitor.

              • dolutegravir

                dolutegravir will increase the level or effect of metformin by decreasing renal clearance. Modify Therapy/Monitor Closely. Dolutegravir inhibits the renal organic cation transporter, OCT2; when used with metformin, limit total daily dose of metformin to 1,000 mg either when starting metformin or dolutegravir; when stopping dolutegravir, adjustment of metformin dose may be necessary; monitor blood glucose when initiating concomitant use and after withdrawal of dolutegravir

              • drospirenone

                drospirenone decreases effects of metformin by pharmacodynamic antagonism. Use Caution/Monitor.

              • dulaglutide

                dulaglutide, metformin. Either increases effects of the other by pharmacodynamic synergism. Use Caution/Monitor. Antidiabetic agents are often used in combination; dosage adjustments may be required when initiating or discontinuing antidiabetic agents.

              • enalapril

                enalapril increases toxicity of metformin by unspecified interaction mechanism. Use Caution/Monitor. Increases risk for hypoglycemia and lactic acidosis.

              • entecavir

                entecavir, metformin. Either increases levels of the other by Other (see comment). Use Caution/Monitor. Comment: Coadministration of entecavir with metformin may increase the risk of lactic acidosis.

              • erdafitinib

                metformin increases levels of erdafitinib by decreasing renal clearance. Modify Therapy/Monitor Closely. Consider alternatives that are not OCT2 substrates or consider reducing the dose of OCT2 substrates based on tolerability.

              • escitalopram

                escitalopram increases effects of metformin by pharmacodynamic synergism. Use Caution/Monitor.

              • estradiol

                estradiol decreases effects of metformin by pharmacodynamic antagonism. Use Caution/Monitor.

              • estrogens conjugated synthetic

                estrogens conjugated synthetic decreases effects of metformin by pharmacodynamic antagonism. Use Caution/Monitor.

              • estropipate

                estropipate decreases effects of metformin by pharmacodynamic antagonism. Use Caution/Monitor.

              • ethacrynic acid

                ethacrynic acid decreases effects of metformin by pharmacodynamic antagonism. Use Caution/Monitor.

              • ethinylestradiol

                ethinylestradiol decreases effects of metformin by pharmacodynamic antagonism. Use Caution/Monitor.

              • ethiodized oil

                ethiodized oil increases toxicity of metformin by unspecified interaction mechanism. Modify Therapy/Monitor Closely. Administration of intravascular iodinated contrast agents in metformin-treated patients has led to rare cases of acute decrease in renal function and the occurrence of lactic acidosis. The American College of Radiology Guidelines (2018) recommend temporarily stopping metformin in patients with eGFR is <30 mL/min/1.73 m2 or who are undergoing arterial catheter studies that might result in emboli to the renal arteries. Continue to withhold metformin for 48 hr subsequent to the procedure and reinstituted only after renal function has been reevaluated and found to be normal. .

              • etonogestrel

                etonogestrel decreases effects of metformin by pharmacodynamic antagonism. Use Caution/Monitor.

              • everolimus

                everolimus decreases effects of metformin by pharmacodynamic antagonism. Use Caution/Monitor.

              • exenatide injectable solution

                exenatide injectable solution, metformin. Either increases effects of the other by pharmacodynamic synergism. Use Caution/Monitor. Concurrent use may increase risk of hypoglycemia; monitor glucose levels.

              • exenatide injectable suspension

                exenatide injectable suspension, metformin. Either increases effects of the other by pharmacodynamic synergism. Use Caution/Monitor. Concurrent use may increase risk of hypoglycemia; monitor glucose levels.

              • felodipine

                felodipine decreases effects of metformin by pharmacodynamic antagonism. Use Caution/Monitor. Patient should be closely observed for loss of blood glucose control; when drugs are withdrawn from a patient receiving metformin, patient should be observed closely for hypoglycemia.

              • fleroxacin

                fleroxacin increases effects of metformin by pharmacodynamic synergism. Use Caution/Monitor. Quinolone antibiotic administration may result in hyper- or hypoglycemia. Gatifloxacin is most likely to produce dysglycemia; moxifloxacin is least likely.

              • fluoxetine

                fluoxetine increases effects of metformin by pharmacodynamic synergism. Use Caution/Monitor.

              • fluphenazine

                fluphenazine decreases effects of metformin by pharmacodynamic antagonism. Use Caution/Monitor. Patient should be closely observed for loss of blood glucose control; when drugs are withdrawn from a patient receiving metformin, patient should be observed closely for hypoglycemia.

              • fluvoxamine

                fluvoxamine increases effects of metformin by pharmacodynamic synergism. Use Caution/Monitor.

              • fosamprenavir

                fosamprenavir decreases effects of metformin by Other (see comment). Use Caution/Monitor. Comment: Reports of hyperglycemia due to insulin resistance with protease inhibitors. .

              • fosinopril

                fosinopril increases toxicity of metformin by unspecified interaction mechanism. Use Caution/Monitor. Increases risk for hypoglycemia and lactic acidosis.

              • fosphenytoin

                fosphenytoin decreases effects of metformin by pharmacodynamic antagonism. Use Caution/Monitor. Patient should be closely observed for loss of blood glucose control; when drugs are withdrawn from a patient receiving metformin, patient should be observed closely for hypoglycemia.

              • gemifloxacin

                gemifloxacin increases effects of metformin by pharmacodynamic synergism. Use Caution/Monitor. Quinolone antibiotic administration may result in hyper- or hypoglycemia. Gatifloxacin is most likely to produce dysglycemia; moxifloxacin is least likely.

              • glucagon intranasal

                glucagon intranasal decreases effects of metformin by pharmacodynamic antagonism. Use Caution/Monitor.

              • glycopyrrolate

                glycopyrrolate increases toxicity of metformin by unspecified interaction mechanism. Use Caution/Monitor. May require a dose reduction.

              • goserelin

                goserelin decreases effects of metformin by pharmacodynamic antagonism. Use Caution/Monitor.

              • histrelin

                histrelin decreases effects of metformin by pharmacodynamic antagonism. Use Caution/Monitor.

              • hydroxyprogesterone caproate

                hydroxyprogesterone caproate decreases effects of metformin by pharmacodynamic antagonism. Use Caution/Monitor.

              • iloperidone

                iloperidone, metformin. Other (see comment). Use Caution/Monitor. Comment: Atypical antipsychotics have been associated with hyperglycemia that may alter blood glucose control; monitor glucose levels closely.

              • imidapril

                imidapril increases toxicity of metformin by unspecified interaction mechanism. Use Caution/Monitor. Increases risk for hypoglycemia and lactic acidosis.

              • indinavir

                indinavir decreases effects of metformin by Other (see comment). Use Caution/Monitor. Comment: Reports of hyperglycemia due to insulin resistance with protease inhibitors. .

              • insulin aspart

                metformin, insulin aspart. Either increases effects of the other by pharmacodynamic synergism. Use Caution/Monitor. Antidiabetic agents are often used in combination; dosage adjustments may be required when initiating or discontinuing antidiabetic agents.

              • insulin aspart protamine/insulin aspart

                metformin, insulin aspart protamine/insulin aspart. Either increases effects of the other by pharmacodynamic synergism. Use Caution/Monitor. Antidiabetic agents are often used in combination; dosage adjustments may be required when initiating or discontinuing antidiabetic agents.

              • insulin degludec

                metformin, insulin degludec. Either increases effects of the other by pharmacodynamic synergism. Use Caution/Monitor. Antidiabetic agents are often used in combination; dosage adjustments may be required when initiating or discontinuing antidiabetic agents.

              • insulin degludec/insulin aspart

                metformin, insulin degludec/insulin aspart. Either increases effects of the other by pharmacodynamic synergism. Use Caution/Monitor. Antidiabetic agents are often used in combination; dosage adjustments may be required when initiating or discontinuing antidiabetic agents.

              • insulin detemir

                metformin, insulin detemir. Either increases effects of the other by pharmacodynamic synergism. Use Caution/Monitor. Antidiabetic agents are often used in combination; dosage adjustments may be required when initiating or discontinuing antidiabetic agents.

              • insulin glargine

                metformin, insulin glargine. Either increases effects of the other by pharmacodynamic synergism. Use Caution/Monitor. Antidiabetic agents are often used in combination; dosage adjustments may be required when initiating or discontinuing antidiabetic agents.

              • insulin glulisine

                metformin, insulin glulisine. Either increases effects of the other by pharmacodynamic synergism. Use Caution/Monitor. Antidiabetic agents are often used in combination; dosage adjustments may be required when initiating or discontinuing antidiabetic agents.

              • insulin inhaled

                metformin, insulin inhaled. Either increases effects of the other by pharmacodynamic synergism. Use Caution/Monitor. Antidiabetic agents are often used in combination; dosage adjustments may be required when initiating or discontinuing antidiabetic agents.

              • insulin isophane human/insulin regular human

                metformin, insulin isophane human/insulin regular human. Either increases effects of the other by pharmacodynamic synergism. Use Caution/Monitor. Antidiabetic agents are often used in combination; dosage adjustments may be required when initiating or discontinuing antidiabetic agents.

              • insulin lispro

                metformin, insulin lispro. Either increases effects of the other by pharmacodynamic synergism. Use Caution/Monitor. Antidiabetic agents are often used in combination; dosage adjustments may be required when initiating or discontinuing antidiabetic agents.

              • insulin lispro protamine/insulin lispro

                metformin, insulin lispro protamine/insulin lispro. Either increases effects of the other by pharmacodynamic synergism. Use Caution/Monitor. Antidiabetic agents are often used in combination; dosage adjustments may be required when initiating or discontinuing antidiabetic agents.

              • insulin NPH

                metformin, insulin NPH. Either increases effects of the other by pharmacodynamic synergism. Use Caution/Monitor. Antidiabetic agents are often used in combination; dosage adjustments may be required when initiating or discontinuing antidiabetic agents.

              • insulin regular human

                metformin, insulin regular human. Either increases effects of the other by pharmacodynamic synergism. Use Caution/Monitor. Antidiabetic agents are often used in combination; dosage adjustments may be required when initiating or discontinuing antidiabetic agents.

              • iodixanol

                iodixanol increases toxicity of metformin by unspecified interaction mechanism. Modify Therapy/Monitor Closely. Administration of intravascular iodinated contrast agents in metformin-treated patients has led to rare cases of acute decrease in renal function and the occurrence of lactic acidosis. The American College of Radiology Guidelines (2018) recommend temporarily stopping metformin in patients with eGFR is <30 mL/min/1.73 m2 or who are undergoing arterial catheter studies that might result in emboli to the renal arteries. Continue to withhold metformin for 48 hr subsequent to the procedure and reinstituted only after renal function has been reevaluated and found to be normal. .

              • ioflupane I 123

                ioflupane I 123 increases toxicity of metformin by unspecified interaction mechanism. Modify Therapy/Monitor Closely. Administration of intravascular iodinated contrast agents in metformin-treated patients has led to rare cases of acute decrease in renal function and the occurrence of lactic acidosis. The American College of Radiology Guidelines (2018) recommend temporarily stopping metformin in patients with eGFR is <30 mL/min/1.73 m2 or who are undergoing arterial catheter studies that might result in emboli to the renal arteries. Continue to withhold metformin for 48 hr subsequent to the procedure and reinstituted only after renal function has been reevaluated and found to be normal. .

              • iohexol

                iohexol increases toxicity of metformin by unspecified interaction mechanism. Modify Therapy/Monitor Closely. Administration of intravascular iodinated contrast agents in metformin-treated patients has led to rare cases of acute decrease in renal function and the occurrence of lactic acidosis. The American College of Radiology Guidelines (2018) recommend temporarily stopping metformin in patients with eGFR is <30 mL/min/1.73 m2 or who are undergoing arterial catheter studies that might result in emboli to the renal arteries. Continue to withhold metformin for 48 hr subsequent to the procedure and reinstituted only after renal function has been reevaluated and found to be normal. .

              • iopamidol

                iopamidol increases toxicity of metformin by unspecified interaction mechanism. Modify Therapy/Monitor Closely. Administration of intravascular iodinated contrast agents in metformin-treated patients has led to rare cases of acute decrease in renal function and the occurrence of lactic acidosis. The American College of Radiology Guidelines (2018) recommend temporarily stopping metformin in patients with eGFR is <30 mL/min/1.73 m2 or who are undergoing arterial catheter studies that might result in emboli to the renal arteries. Continue to withhold metformin for 48 hr subsequent to the procedure and reinstituted only after renal function has been reevaluated and found to be normal. .

              • iopromide

                iopromide increases toxicity of metformin by unspecified interaction mechanism. Modify Therapy/Monitor Closely. Administration of intravascular iodinated contrast agents in metformin-treated patients has led to rare cases of acute decrease in renal function and the occurrence of lactic acidosis. The American College of Radiology Guidelines (2018) recommend temporarily stopping metformin in patients with eGFR is <30 mL/min/1.73 m2 or who are undergoing arterial catheter studies that might result in emboli to the renal arteries. Continue to withhold metformin for 48 hr subsequent to the procedure and reinstituted only after renal function has been reevaluated and found to be normal. .

              • ioversol

                ioversol increases toxicity of metformin by unspecified interaction mechanism. Modify Therapy/Monitor Closely. Administration of intravascular iodinated contrast agents in metformin-treated patients has led to rare cases of acute decrease in renal function and the occurrence of lactic acidosis. The American College of Radiology Guidelines (2018) recommend temporarily stopping metformin in patients with eGFR is <30 mL/min/1.73 m2 or who are undergoing arterial catheter studies that might result in emboli to the renal arteries. Continue to withhold metformin for 48 hr subsequent to the procedure and reinstituted only after renal function has been reevaluated and found to be normal. .

              • ioxilan

                ioxilan increases toxicity of metformin by unspecified interaction mechanism. Modify Therapy/Monitor Closely. Administration of intravascular iodinated contrast agents in metformin-treated patients has led to rare cases of acute decrease in renal function and the occurrence of lactic acidosis. The American College of Radiology Guidelines (2018) recommend temporarily stopping metformin in patients with eGFR is <30 mL/min/1.73 m2 or who are undergoing arterial catheter studies that might result in emboli to the renal arteries. Continue to withhold metformin for 48 hr subsequent to the procedure and reinstituted only after renal function has been reevaluated and found to be normal. .

              • isocarboxazid

                isocarboxazid will increase the level or effect of metformin by unspecified interaction mechanism. Use Caution/Monitor.

              • isoniazid

                isoniazid decreases effects of metformin by unspecified interaction mechanism. Use Caution/Monitor. Patient should be closely observed for loss of blood glucose control; when drugs are withdrawn from a patient receiving metformin, patient should be observed closely for hypoglycemia.

              • isradipine

                isradipine decreases effects of metformin by pharmacodynamic antagonism. Use Caution/Monitor. Patient should be closely observed for loss of blood glucose control; when drugs are withdrawn from a patient receiving metformin, patient should be observed closely for hypoglycemia.

              • ketotifen, ophthalmic

                ketotifen, ophthalmic, metformin. Other (see comment). Use Caution/Monitor. Comment: Combination may result in thrombocytopenia (rare). Monitor CBC.

              • lanreotide

                lanreotide decreases effects of metformin by pharmacodynamic antagonism. Use Caution/Monitor.

              • leuprolide

                leuprolide decreases effects of metformin by pharmacodynamic antagonism. Use Caution/Monitor.

              • levofloxacin

                levofloxacin increases effects of metformin by pharmacodynamic synergism. Use Caution/Monitor. Quinolone antibiotic administration may result in hyper- or hypoglycemia. Gatifloxacin is most likely to produce dysglycemia; moxifloxacin is least likely.

              • levonorgestrel intrauterine

                levonorgestrel intrauterine decreases effects of metformin by pharmacodynamic antagonism. Use Caution/Monitor.

              • levonorgestrel oral

                levonorgestrel oral decreases effects of metformin by pharmacodynamic antagonism. Use Caution/Monitor.

              • levothyroxine

                levothyroxine decreases effects of metformin by pharmacodynamic antagonism. Use Caution/Monitor. Patient should be closely observed for loss of blood glucose control; when drugs are withdrawn from a patient receiving metformin, patient should be observed closely for hypoglycemia.

              • linezolid

                linezolid will increase the level or effect of metformin by unspecified interaction mechanism. Use Caution/Monitor.

              • liothyronine

                liothyronine decreases effects of metformin by pharmacodynamic antagonism. Use Caution/Monitor. Patient should be closely observed for loss of blood glucose control; when drugs are withdrawn from a patient receiving metformin, patient should be observed closely for hypoglycemia.

              • liotrix

                liotrix decreases effects of metformin by pharmacodynamic antagonism. Use Caution/Monitor. Patient should be closely observed for loss of blood glucose control; when drugs are withdrawn from a patient receiving metformin, patient should be observed closely for hypoglycemia.

              • liraglutide

                liraglutide, metformin. Either increases effects of the other by pharmacodynamic synergism. Use Caution/Monitor. Concurrent use may increase risk of hypoglycemia; monitor glucose levels.

              • lisinopril

                lisinopril increases toxicity of metformin by unspecified interaction mechanism. Use Caution/Monitor. Increases risk for hypoglycemia and lactic acidosis.

              • lopinavir

                lopinavir decreases effects of metformin by Other (see comment). Use Caution/Monitor. Comment: Reports of hyperglycemia due to insulin resistance with protease inhibitors. .

              • lurasidone

                lurasidone, metformin. Other (see comment). Use Caution/Monitor. Comment: Atypical antipsychotics have been associated with hyperglycemia that may alter blood glucose control; monitor glucose levels closely.

              • marijuana

                marijuana decreases effects of metformin by pharmacodynamic antagonism. Use Caution/Monitor.

              • mecasermin

                mecasermin increases effects of metformin by pharmacodynamic synergism. Use Caution/Monitor. Additive hypoglycemic effects.

              • medroxyprogesterone

                medroxyprogesterone decreases effects of metformin by pharmacodynamic antagonism. Use Caution/Monitor.

              • methamphetamine

                methamphetamine decreases effects of metformin by pharmacodynamic antagonism. Use Caution/Monitor. Patient should be closely observed for loss of blood glucose control; when drugs are withdrawn from a patient receiving metformin, patient should be observed closely for hypoglycemia.

              • methazolamide

                methazolamide increases toxicity of metformin by Other (see comment). Use Caution/Monitor. Comment: Decreases serum bicarbonate and induce non-anion gap, hyperchloremic metabolic acidosis.

              • moexipril

                moexipril increases toxicity of metformin by unspecified interaction mechanism. Use Caution/Monitor. Increases risk for hypoglycemia and lactic acidosis.

              • moxifloxacin

                moxifloxacin increases effects of metformin by pharmacodynamic synergism. Use Caution/Monitor. Quinolone antibiotic administration may result in hyper- or hypoglycemia. Gatifloxacin is most likely to produce dysglycemia; moxifloxacin is least likely.

              • nelfinavir

                nelfinavir decreases effects of metformin by Other (see comment). Use Caution/Monitor. Comment: Reports of hyperglycemia due to insulin resistance with protease inhibitors. .

              • niacin

                niacin decreases effects of metformin by pharmacodynamic antagonism. Use Caution/Monitor. Patient should be closely observed for loss of blood glucose control; when drugs are withdrawn from a patient receiving metformin, patient should be observed closely for hypoglycemia.

              • nicardipine

                nicardipine decreases effects of metformin by pharmacodynamic antagonism. Use Caution/Monitor. Patient should be closely observed for loss of blood glucose control; when drugs are withdrawn from a patient receiving metformin, patient should be observed closely for hypoglycemia.

              • nifedipine

                nifedipine decreases effects of metformin by pharmacodynamic antagonism. Use Caution/Monitor. Patient should be closely observed for loss of blood glucose control; when drugs are withdrawn from a patient receiving metformin, patient should be observed closely for hypoglycemia.

              • nilotinib

                nilotinib decreases effects of metformin by pharmacodynamic antagonism. Use Caution/Monitor.

              • nimodipine

                nimodipine decreases effects of metformin by pharmacodynamic antagonism. Use Caution/Monitor. Patient should be closely observed for loss of blood glucose control; when drugs are withdrawn from a patient receiving metformin, patient should be observed closely for hypoglycemia.

              • nisoldipine

                nisoldipine decreases effects of metformin by pharmacodynamic antagonism. Use Caution/Monitor. Patient should be closely observed for loss of blood glucose control; when drugs are withdrawn from a patient receiving metformin, patient should be observed closely for hypoglycemia.

              • nizatidine

                nizatidine will increase the level or effect of metformin by decreasing renal clearance. Modify Therapy/Monitor Closely.

              • norelgestromin

                norelgestromin decreases effects of metformin by pharmacodynamic antagonism. Use Caution/Monitor.

              • norethindrone

                norethindrone decreases effects of metformin by pharmacodynamic antagonism. Use Caution/Monitor.

              • norgestimate

                norgestimate decreases effects of metformin by pharmacodynamic antagonism. Use Caution/Monitor.

              • octreotide

                octreotide decreases effects of metformin by pharmacodynamic antagonism. Use Caution/Monitor.

              • ofloxacin

                ofloxacin increases effects of metformin by pharmacodynamic synergism. Use Caution/Monitor. Quinolone antibiotic administration may result in hyper- or hypoglycemia. Gatifloxacin is most likely to produce dysglycemia; moxifloxacin is least likely.

              • olanzapine

                olanzapine, metformin. Other (see comment). Use Caution/Monitor. Comment: Atypical antipsychotics have been associated with hyperglycemia that may alter blood glucose control; monitor glucose levels closely.

              • omacetaxine

                omacetaxine decreases effects of metformin by pharmacodynamic antagonism. Use Caution/Monitor.

              • ombitasvir/paritaprevir/ritonavir & dasabuvir

                ombitasvir/paritaprevir/ritonavir & dasabuvir increases toxicity of metformin by unspecified interaction mechanism. Use Caution/Monitor. Monitor for signs of onset of lactic acidosis such as respiratory distress, somnolence, and non-specific abdominal distress or worsening renal function; concomitant metformin use in patients with renal insufficiency or hepatic impairment not recommended.

              • ondansetron

                ondansetron increases levels of metformin by Other (see comment). Use Caution/Monitor. Comment: Ondansetron inhibition of transporters (MATE or OCTs), which are responsible for active renal secretion of metformin may play a role.

              • opuntia ficus indica

                opuntia ficus indica increases effects of metformin by pharmacodynamic synergism. Use Caution/Monitor.

              • paliperidone

                paliperidone, metformin. Other (see comment). Use Caution/Monitor. Comment: Atypical antipsychotics have been associated with hyperglycemia that may alter blood glucose control; monitor glucose levels closely.

              • paroxetine

                paroxetine increases effects of metformin by pharmacodynamic synergism. Use Caution/Monitor.

              • pasireotide

                pasireotide decreases effects of metformin by pharmacodynamic antagonism. Use Caution/Monitor.

              • patiromer

                patiromer will decrease the level or effect of metformin by drug binding in GI tract. Use Caution/Monitor. May administer 3 hours apart

              • pentamidine

                pentamidine decreases effects of metformin by pharmacodynamic antagonism. Use Caution/Monitor.

              • perindopril

                perindopril increases toxicity of metformin by unspecified interaction mechanism. Use Caution/Monitor. Increases risk for hypoglycemia and lactic acidosis.

              • perphenazine

                perphenazine decreases effects of metformin by pharmacodynamic antagonism. Use Caution/Monitor. Patient should be closely observed for loss of blood glucose control; when drugs are withdrawn from a patient receiving metformin, patient should be observed closely for hypoglycemia.

              • phendimetrazine

                phendimetrazine decreases effects of metformin by pharmacodynamic antagonism. Use Caution/Monitor. Patient should be closely observed for loss of blood glucose control; when drugs are withdrawn from a patient receiving metformin, patient should be observed closely for hypoglycemia.

              • phenelzine

                phenelzine will increase the level or effect of metformin by unspecified interaction mechanism. Use Caution/Monitor.

              • phentermine

                phentermine decreases effects of metformin by pharmacodynamic antagonism. Use Caution/Monitor. Patient should be closely observed for loss of blood glucose control; when drugs are withdrawn from a patient receiving metformin, patient should be observed closely for hypoglycemia.

              • phenytoin

                phenytoin decreases effects of metformin by pharmacodynamic antagonism. Use Caution/Monitor. Patient should be closely observed for loss of blood glucose control; when drugs are withdrawn from a patient receiving metformin, patient should be observed closely for hypoglycemia.

              • procainamide

                metformin will increase the level or effect of procainamide by basic (cationic) drug competition for renal tubular clearance. Use Caution/Monitor.

              • procarbazine

                procarbazine will increase the level or effect of metformin by unspecified interaction mechanism. Use Caution/Monitor.

              • prochlorperazine

                prochlorperazine decreases effects of metformin by pharmacodynamic antagonism. Use Caution/Monitor. Patient should be closely observed for loss of blood glucose control; when drugs are withdrawn from a patient receiving metformin, patient should be observed closely for hypoglycemia.

              • progesterone intravaginal gel

                progesterone intravaginal gel decreases effects of metformin by pharmacodynamic antagonism. Use Caution/Monitor.

              • progesterone micronized

                progesterone micronized decreases effects of metformin by pharmacodynamic antagonism. Use Caution/Monitor.

              • progesterone, natural

                progesterone, natural decreases effects of metformin by pharmacodynamic antagonism. Use Caution/Monitor.

              • promethazine

                promethazine decreases effects of metformin by pharmacodynamic antagonism. Use Caution/Monitor. Patient should be closely observed for loss of blood glucose control; when drugs are withdrawn from a patient receiving metformin, patient should be observed closely for hypoglycemia.

              • quetiapine

                quetiapine, metformin. Other (see comment). Use Caution/Monitor. Comment: Atypical antipsychotics have been associated with hyperglycemia that may alter blood glucose control; monitor glucose levels closely.

              • quinapril

                quinapril increases toxicity of metformin by unspecified interaction mechanism. Use Caution/Monitor. Increases risk for hypoglycemia and lactic acidosis.

              • quinidine

                quinidine will increase the level or effect of metformin by basic (cationic) drug competition for renal tubular clearance. Use Caution/Monitor.

              • ramipril

                ramipril increases toxicity of metformin by unspecified interaction mechanism. Use Caution/Monitor. Increases risk for hypoglycemia and lactic acidosis.

              • rasagiline

                rasagiline will increase the level or effect of metformin by unspecified interaction mechanism. Use Caution/Monitor.

              • risperidone

                risperidone, metformin. Other (see comment). Use Caution/Monitor. Comment: Atypical antipsychotics have been associated with hyperglycemia that may alter blood glucose control; monitor glucose levels closely.

              • ritonavir

                ritonavir decreases effects of metformin by Other (see comment). Use Caution/Monitor. Comment: Reports of hyperglycemia due to insulin resistance with protease inhibitors. .

              • saquinavir

                saquinavir decreases effects of metformin by Other (see comment). Use Caution/Monitor. Comment: Reports of hyperglycemia due to insulin resistance with protease inhibitors. .

              • sertraline

                sertraline increases effects of metformin by pharmacodynamic synergism. Use Caution/Monitor.

              • shark cartilage

                shark cartilage increases effects of metformin by pharmacodynamic synergism. Use Caution/Monitor. Theoretical interaction.

              • sirolimus

                sirolimus decreases levels of metformin by pharmacodynamic antagonism. Use Caution/Monitor.

              • somapacitan

                somapacitan decreases effects of metformin by pharmacodynamic antagonism. Modify Therapy/Monitor Closely. Growth hormone products may decrease insulin sensitivity, particularly at higher doses. Antidiabetic agents may require dose adjustment after initiating somapacitan. .

              • somatropin

                somatropin decreases levels of metformin by pharmacodynamic antagonism. Use Caution/Monitor.

              • sulfamethoxypyridazine

                sulfamethoxypyridazine increases effects of metformin by unspecified interaction mechanism. Use Caution/Monitor. Risk of hypoglycemia.

              • tacrolimus

                tacrolimus decreases effects of metformin by pharmacodynamic antagonism. Use Caution/Monitor.

              • temsirolimus

                temsirolimus decreases effects of metformin by pharmacodynamic antagonism. Use Caution/Monitor.

              • tenofovir DF

                tenofovir DF increases levels of metformin by decreasing renal clearance. Use Caution/Monitor. Increased risk of lactic acidosis.

              • thioridazine

                thioridazine decreases effects of metformin by pharmacodynamic antagonism. Use Caution/Monitor. Patient should be closely observed for loss of blood glucose control; when drugs are withdrawn from a patient receiving metformin, patient should be observed closely for hypoglycemia.

              • thyroid desiccated

                thyroid desiccated decreases effects of metformin by pharmacodynamic antagonism. Use Caution/Monitor. Patient should be closely observed for loss of blood glucose control; when drugs are withdrawn from a patient receiving metformin, patient should be observed closely for hypoglycemia.

              • tibolone

                tibolone decreases effects of metformin by pharmacodynamic antagonism. Use Caution/Monitor.

              • tipranavir

                tipranavir decreases effects of metformin by Other (see comment). Use Caution/Monitor. Comment: Reports of hyperglycemia due to insulin resistance with protease inhibitors. .

              • topiramate

                topiramate increases toxicity of metformin by Other (see comment). Use Caution/Monitor. Comment: Decreases serum bicarbonate and induce non-anion gap, hyperchloremic metabolic acidosis.

              • torsemide

                torsemide decreases effects of metformin by pharmacodynamic antagonism. Use Caution/Monitor.

              • trandolapril

                trandolapril increases toxicity of metformin by unspecified interaction mechanism. Use Caution/Monitor. Increases risk for hypoglycemia and lactic acidosis.

              • triamcinolone acetonide injectable suspension

                triamcinolone acetonide injectable suspension decreases effects of metformin by pharmacodynamic antagonism. Use Caution/Monitor. Corticosteroids may diminish hypoglycemic effect of antidiabetic agents. Monitor blood glucose levels carefully.

              • trifluoperazine

                trifluoperazine decreases effects of metformin by pharmacodynamic antagonism. Use Caution/Monitor. Patient should be closely observed for loss of blood glucose control; when drugs are withdrawn from a patient receiving metformin, patient should be observed closely for hypoglycemia.

              • trimethoprim

                trimethoprim increases levels of metformin by Other (see comment). Use Caution/Monitor. Comment: Trimethoprim may inhibit active renal tubular secretion of metformin (eg, via OCT2, MATE1); dose adjustments may be necessary.

              • triptorelin

                triptorelin decreases effects of metformin by pharmacodynamic antagonism. Use Caution/Monitor.

              • trospium chloride

                metformin will decrease the level or effect of trospium chloride by increasing renal clearance. Use Caution/Monitor. Coadministration reduced steady state trospium systemic exposure (decreased AUC and Cmax) by competing for renal tubular secretion

              • vandetanib

                vandetanib increases levels of metformin by Other (see comment). Modify Therapy/Monitor Closely. Comment: Vandetanib inhibits the uptake of substrates of organic cation transporter type 2 (OCT2).

              • verapamil

                verapamil decreases effects of metformin by Other (see comment). Use Caution/Monitor. Comment: Verapamil may inhibit hepatic uptake of metformin by OCT1 and/or other transporters.

              • vilazodone

                vilazodone increases effects of metformin by pharmacodynamic synergism. Use Caution/Monitor.

              • vorinostat

                vorinostat decreases effects of metformin by pharmacodynamic antagonism. Use Caution/Monitor.

              • vortioxetine

                vortioxetine increases effects of metformin by pharmacodynamic synergism. Use Caution/Monitor.

              • xipamide

                xipamide decreases levels of metformin by increasing renal clearance. Use Caution/Monitor.

              • ziprasidone

                ziprasidone, metformin. Other (see comment). Use Caution/Monitor. Comment: Atypical antipsychotics have been associated with hyperglycemia that may alter blood glucose control; monitor glucose levels closely.

              • zonisamide

                zonisamide increases toxicity of metformin by Other (see comment). Use Caution/Monitor. Comment: Decreases serum bicarbonate and induce non-anion gap, hyperchloremic metabolic acidosis.

              Minor (82)

              • agrimony

                agrimony increases effects of metformin by pharmacodynamic synergism. Minor/Significance Unknown.

              • American ginseng

                American ginseng increases effects of metformin by pharmacodynamic synergism. Minor/Significance Unknown.

              • amitriptyline

                amitriptyline increases effects of metformin by pharmacodynamic synergism. Minor/Significance Unknown.

              • amoxapine

                amoxapine increases effects of metformin by pharmacodynamic synergism. Minor/Significance Unknown.

              • anamu

                anamu increases effects of metformin by pharmacodynamic synergism. Minor/Significance Unknown. Theoretical interaction.

              • bendroflumethiazide

                bendroflumethiazide decreases effects of metformin by pharmacodynamic antagonism. Minor/Significance Unknown. Thiazide dosage >50 mg/day may increase blood glucose.

              • budesonide

                budesonide decreases effects of metformin by pharmacodynamic antagonism. Minor/Significance Unknown.

              • chlorothiazide

                chlorothiazide decreases effects of metformin by pharmacodynamic antagonism. Minor/Significance Unknown. Thiazide dosage >50 mg/day may increase blood glucose.

              • chlorthalidone

                chlorthalidone decreases effects of metformin by pharmacodynamic antagonism. Minor/Significance Unknown. Thiazide dosage >50 mg/day may increase blood glucose.

              • chromium

                chromium increases effects of metformin by pharmacodynamic synergism. Minor/Significance Unknown.

              • clomipramine

                clomipramine increases effects of metformin by pharmacodynamic synergism. Minor/Significance Unknown.

              • clonidine

                clonidine decreases effects of metformin by pharmacodynamic antagonism. Minor/Significance Unknown. Diminished symptoms of hypoglycemia.

                clonidine, metformin. Other (see comment). Minor/Significance Unknown. Comment: Decreased symptoms of hypoglycemia. Mechanism: decreased hypoglycemia induced catecholamine production.

              • cornsilk

                cornsilk increases effects of metformin by pharmacodynamic synergism. Minor/Significance Unknown. Increased risk of hypoglycemia (theoretical interaction).

              • cortisone

                cortisone decreases effects of metformin by pharmacodynamic antagonism. Minor/Significance Unknown.

              • cyanocobalamin

                metformin decreases levels of cyanocobalamin by unspecified interaction mechanism. Minor/Significance Unknown. It may take several years of metformin therapy to develop vitamin B12 deficiency.

              • cyclopenthiazide

                cyclopenthiazide decreases effects of metformin by pharmacodynamic antagonism. Minor/Significance Unknown. Thiazide dosage >50 mg/day may increase blood glucose.

              • damiana

                damiana decreases effects of metformin by pharmacodynamic antagonism. Minor/Significance Unknown. Theoretical interaction.

              • danazol

                danazol increases effects of metformin by pharmacodynamic synergism. Minor/Significance Unknown.

              • deflazacort

                deflazacort decreases effects of metformin by pharmacodynamic antagonism. Minor/Significance Unknown.

              • desipramine

                desipramine increases effects of metformin by pharmacodynamic synergism. Minor/Significance Unknown.

              • devil's claw

                devil's claw increases effects of metformin by pharmacodynamic synergism. Minor/Significance Unknown.

              • dexamethasone

                dexamethasone decreases effects of metformin by pharmacodynamic antagonism. Minor/Significance Unknown.

              • diltiazem

                diltiazem will increase the level or effect of metformin by basic (cationic) drug competition for renal tubular clearance. Minor/Significance Unknown.

              • doxepin

                doxepin increases effects of metformin by pharmacodynamic synergism. Minor/Significance Unknown.

              • elderberry

                elderberry increases effects of metformin by pharmacodynamic synergism. Minor/Significance Unknown. Increased risk of hypoglycemia (in vitro research).

              • eucalyptus

                eucalyptus increases effects of metformin by pharmacodynamic synergism. Minor/Significance Unknown. Theoretical interaction.

              • famotidine

                famotidine increases levels of metformin by decreasing renal clearance. Minor/Significance Unknown.

              • fludrocortisone

                fludrocortisone decreases effects of metformin by pharmacodynamic antagonism. Minor/Significance Unknown.

              • fluoxymesterone

                fluoxymesterone increases effects of metformin by pharmacodynamic synergism. Minor/Significance Unknown.

              • fo-ti

                fo-ti increases effects of metformin by pharmacodynamic synergism. Minor/Significance Unknown.

              • folic acid

                metformin decreases levels of folic acid by unspecified interaction mechanism. Minor/Significance Unknown.

              • forskolin

                forskolin increases effects of metformin by pharmacodynamic synergism. Minor/Significance Unknown. Colenol, a compound found in Coleus root, may stimulate insulin release.

              • furosemide

                metformin decreases levels of furosemide by unspecified interaction mechanism. Minor/Significance Unknown.

                furosemide increases levels of metformin by unspecified interaction mechanism. Minor/Significance Unknown. Patient should be closely observed for loss of blood glucose control; when drugs are withdrawn from a patient receiving metformin, patient should be observed closely for hypoglycemia.

              • gotu kola

                gotu kola increases effects of metformin by pharmacodynamic synergism. Minor/Significance Unknown. (Theoretical interaction).

              • guanfacine

                guanfacine decreases effects of metformin by pharmacodynamic antagonism. Minor/Significance Unknown. Diminished symptoms of hypoglycemia.

                guanfacine, metformin. Other (see comment). Minor/Significance Unknown. Comment: Decreased symptoms of hypoglycemia. Mechanism: decreased hypoglycemia induced catecholamine production.

              • gymnema

                gymnema increases effects of metformin by pharmacodynamic synergism. Minor/Significance Unknown.

              • horse chestnut seed

                horse chestnut seed increases effects of metformin by pharmacodynamic synergism. Minor/Significance Unknown.

              • hydrochlorothiazide

                hydrochlorothiazide will increase the level or effect of metformin by basic (cationic) drug competition for renal tubular clearance. Minor/Significance Unknown.

                hydrochlorothiazide decreases effects of metformin by pharmacodynamic antagonism. Minor/Significance Unknown. Thiazide dosage >50 mg/day may increase blood glucose.

              • hydrocortisone

                hydrocortisone decreases effects of metformin by pharmacodynamic antagonism. Minor/Significance Unknown.

              • ibuprofen/famotidine

                ibuprofen/famotidine increases levels of metformin by decreasing renal clearance. Minor/Significance Unknown.

              • imipramine

                imipramine increases effects of metformin by pharmacodynamic synergism. Minor/Significance Unknown.

              • indapamide

                indapamide decreases effects of metformin by pharmacodynamic antagonism. Minor/Significance Unknown. Thiazide dosage >50 mg/day may increase blood glucose.

              • juniper

                juniper increases effects of metformin by pharmacodynamic synergism. Minor/Significance Unknown. Increased risk of hypoglycemia (theoretical interaction).

              • L-methylfolate

                metformin decreases levels of L-methylfolate by unspecified interaction mechanism. Minor/Significance Unknown.

              • lofepramine

                lofepramine increases effects of metformin by pharmacodynamic synergism. Minor/Significance Unknown.

              • lycopus

                lycopus increases effects of metformin by pharmacodynamic synergism. Minor/Significance Unknown. Increased risk of hypoglycemia (theoretical interaction).

              • maitake

                maitake increases effects of metformin by pharmacodynamic synergism. Minor/Significance Unknown. Increased risk of hypoglycemia (animal research).

              • maprotiline

                maprotiline increases effects of metformin by pharmacodynamic synergism. Minor/Significance Unknown.

              • memantine

                memantine will increase the level or effect of metformin by basic (cationic) drug competition for renal tubular clearance. Minor/Significance Unknown.

              • mesterolone

                mesterolone increases effects of metformin by pharmacodynamic synergism. Minor/Significance Unknown.

              • methyclothiazide

                methyclothiazide will increase the level or effect of metformin by basic (cationic) drug competition for renal tubular clearance. Minor/Significance Unknown.

                methyclothiazide decreases effects of metformin by pharmacodynamic antagonism. Minor/Significance Unknown. Thiazide dosage >50 mg/day may increase blood glucose.

              • methylprednisolone

                methylprednisolone decreases effects of metformin by pharmacodynamic antagonism. Minor/Significance Unknown.

              • methyltestosterone

                methyltestosterone increases effects of metformin by pharmacodynamic synergism. Minor/Significance Unknown.

              • metolazone

                metolazone decreases effects of metformin by pharmacodynamic antagonism. Minor/Significance Unknown. Thiazide dosage >50 mg/day may increase blood glucose.

              • midodrine

                metformin will increase the level or effect of midodrine by basic (cationic) drug competition for renal tubular clearance. Minor/Significance Unknown.

              • nettle

                nettle increases effects of metformin by pharmacodynamic synergism. Minor/Significance Unknown. (Theoretical interaction).

              • nifedipine

                nifedipine increases levels of metformin by enhancing GI absorption. Applies only to oral form of both agents. Minor/Significance Unknown.

              • nortriptyline

                nortriptyline increases effects of metformin by pharmacodynamic synergism. Minor/Significance Unknown.

              • ofloxacin

                metformin will increase the level or effect of ofloxacin by basic (cationic) drug competition for renal tubular clearance. Minor/Significance Unknown.

                ofloxacin, metformin. Mechanism: unspecified interaction mechanism. Minor/Significance Unknown. Potential dysglycemia.

              • oxandrolone

                oxandrolone increases effects of metformin by pharmacodynamic synergism. Minor/Significance Unknown.

              • oxymetholone

                oxymetholone increases effects of metformin by pharmacodynamic synergism. Minor/Significance Unknown.

              • pegvisomant

                pegvisomant increases effects of metformin by pharmacodynamic synergism. Minor/Significance Unknown.

              • potassium acid phosphate

                potassium acid phosphate increases effects of metformin by pharmacodynamic synergism. Minor/Significance Unknown. Interaction especially seen in the treatment of hypokalemia.

              • potassium chloride

                potassium chloride increases effects of metformin by pharmacodynamic synergism. Minor/Significance Unknown. Interaction especially seen in the treatment of hypokalemia.

              • potassium citrate

                potassium citrate increases effects of metformin by pharmacodynamic synergism. Minor/Significance Unknown. Interaction especially seen in the treatment of hypokalemia.

              • prednisolone

                prednisolone decreases effects of metformin by pharmacodynamic antagonism. Minor/Significance Unknown.

              • prednisone

                prednisone decreases effects of metformin by pharmacodynamic antagonism. Minor/Significance Unknown.

              • protriptyline

                protriptyline increases effects of metformin by pharmacodynamic synergism. Minor/Significance Unknown.

              • quinine

                metformin will increase the level or effect of quinine by basic (cationic) drug competition for renal tubular clearance. Minor/Significance Unknown.

              • sage

                sage increases effects of metformin by pharmacodynamic synergism. Minor/Significance Unknown.

              • stevia

                stevia increases effects of metformin by pharmacodynamic synergism. Minor/Significance Unknown.

              • sulfamethoxazole

                sulfamethoxazole will increase the level or effect of metformin by basic (cationic) drug competition for renal tubular clearance. Minor/Significance Unknown.

              • testosterone

                testosterone increases effects of metformin by pharmacodynamic synergism. Minor/Significance Unknown.

              • testosterone buccal system

                testosterone buccal system increases effects of metformin by pharmacodynamic synergism. Minor/Significance Unknown.

              • testosterone topical

                testosterone topical increases effects of metformin by pharmacodynamic synergism. Minor/Significance Unknown.

              • tongkat ali

                tongkat ali increases effects of metformin by pharmacodynamic synergism. Minor/Significance Unknown. Risk of hypoglycemia.

              • trazodone

                trazodone increases effects of metformin by pharmacodynamic synergism. Minor/Significance Unknown.

              • triamterene

                metformin will increase the level or effect of triamterene by basic (cationic) drug competition for renal tubular clearance. Minor/Significance Unknown.

              • trimethoprim

                metformin will increase the level or effect of trimethoprim by basic (cationic) drug competition for renal tubular clearance. Minor/Significance Unknown.

              • trimipramine

                trimipramine increases effects of metformin by pharmacodynamic synergism. Minor/Significance Unknown.

              • vanadium

                vanadium increases effects of metformin by pharmacodynamic synergism. Minor/Significance Unknown.

              • verapamil

                metformin will increase the level or effect of verapamil by basic (cationic) drug competition for renal tubular clearance. Minor/Significance Unknown.

              Previous
              Next:

              Adverse Effects

              Frequency Not Defined

              Asthenia

              Diarrhea

              Flatulence

              Weakness

              Myalgia

              Upper respiratory tract infection

              Hypoglycemia

              GI complaints

              Lactic acidosis (rare)

              Low serum vitamin B-12

              Nausea/vomiting

              Chest discomfort

              Chills

              Dizziness

              Abdominal distention

              Constipation

              Heartburn

              Dyspepsia

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              Warnings

              Black Box Warnings

              Lactic acidosis is a rare, but potentially severe, consequence of therapy with metformin; it is characterized by elevated blood lactate levels (>5 mmol/L), decreased blood pH, electrolyte disturbances with an increased anion gap, and an increased lactate/pyruvate ratio; when metformin is implicated as the cause of lactic acidosis, metformin plasma concentrations >5 mcg/mL are generally found

              Risk factors for metformin-associated lactic acidosis include renal impairment, concomitant use of certain drugs (eg, carbonic anhydrase inhibitors such as topiramate), age 65 years old or greater, having a radiological study with contrast, surgery and other procedures, hypoxic states (e.g., acute congestive heart failure), excessive alcohol intake, and hepatic impairment; if metformin-associated lactic acidosis is suspected, immediately discontinue

              Patients with CHF requiring pharmacologic management, in particular those with unstable or acute CHF who are at risk for hypoperfusion and hypoxemia, are at an increased risk for lactic acidosis; the risk for lactic acidosis increases with the degree of renal dysfunction and the patient’s age

              Do not start in patients aged 80 years or older unless CrCl demonstrates that renal function is not reduced, because these patients are more susceptible to developing lactic acidosis; metformin should be promptly withheld in the presence of any condition associated with hypoxemia, dehydration, or sepsis

              Should generally be avoided in patients with clinical or laboratory evidence of hepatic disease; patients should be cautioned against excessive alcohol intake, either acute or chronic, during metformin therapy because alcohol potentiates the effects of metformin on lactate metabolism

              Discontinue metformin at the time of or before an iodinated contrast imaging procedure in patients with an eGFR between 30-60 mL/minute/1.73 m²; in patients with a history of liver disease, alcoholism, or heart failure; or in patients who will be administered intra-arterial iodinate contrast

              The onset of lactic acidosis often is subtle and accompanied by nonspecific symptoms (eg, malaise, myalgias, respiratory distress, increasing somnolence, nonspecific abdominal distress); with marked acidosis, hypothermia, hypotension, and resistant bradyarrhythmias may occur; patients should be instructed regarding recognition of these symptoms and told to notify their physician immediately if the symptoms occur; metformin should be withdrawn until the situation is clarified; serum electrolytes, ketones, blood glucose, and, if indicated, blood pH, lactate levels, and even blood metformin levels may be useful

              Once a patient is stabilized on any dose level of metformin, GI symptoms, which are common during initiation of therapy, are unlikely to be drug related; later occurrences of GI symptoms could be due to lactic acidosis or other serious disease

              Lactic acidosis should be suspected in any diabetic patient with metabolic acidosis who is lacking evidence of ketoacidosis (ketonuria and ketonemia); lactic acidosis is a medical emergency that must be treated in a hospital setting; in a patient with lactic acidosis who is taking metformin, the drug should be discontinued immediately and general supportive care measures promptly instituted; metformin is highly dialyzable (clearance up to 170 mL/min under good hemodynamic conditions); prompt hemodialysis is recommended to correct the acidosis and to remove the accumulated metformin; such management often results in prompt reversal of symptoms and recovery

              Contraindications

              Hypersensitivity to metformin

              CHF

              Diabetic ketoacidosis with or without coma

              Severe renal disease: eGFR <30 mL/min/1.73 m²

              Abnormal creatinine clearance resulting from shock, septicemia, or myocardial infarction

              Lactation

              Cautions

              Increased risk of severe hypoglycemia especially in elderly, debilitated or malnourished, adrenal or pituitary insufficiency, dehydration, heavy alcohol use, hypoxic states, hepatic/renal impairment, stress due to infection, fever, trauma, or surgery

              Concomitant administration of insulin and insulin secretagogues (e.g., sulfonylurea) may increase risk of hypoglycemia; therefore, a lower dose of insulin or insulin secretagogue may be required to minimize risk of hypoglycemia when used in combination with metformin

              Withholding of food and fluids during surgical or other procedures may increase risk for volume depletion, hypotension, and renal impairment; therapy should be temporarily discontinued while patients have restricted food and fluid intake

              Rare lactic acidosis may occur due to metformin accumulation; fatal in approximately 50% of cases; risk increases with age, degree of renal dysfunction, and with unstable or acute CHF; if metformin-associated lactic acidosis suspected, general supportive measures should be instituted promptly in a hospital setting, along with immediate discontinuation of therapy; in patients with a diagnosis or strong suspicion of lactic acidosis, prompt hemodialysis is recommended to correct acidosis and remove accumulated metformin (metformin hydrochloride is dialyzable, with a clearance of up to170 mL/minute under good hemodynamic conditions); hemodialysis has often resulted in reversal of symptoms and recovery

              Possible increased risk of CV mortality

              May cause ovulation in anovulatory and premenopausal PCOS patients

              May be necessary to discontinue therapy with metformin and administer insulin if patient is exposed to stress (fever, trauma, infection), or experiences diabetic ketoacidosis

              Several of the postmarketing cases of metformin-associated lactic acidosis occurred in setting of acute congestive heart failure (particularly when accompanied by hypoperfusion and hypoxemia); cardiovascular collapse (shock) acute myocardial infarction, sepsis, and other conditions associated with hypoxemia have been associated with lactic acidosis and may also cause prerenal azotemia; discontinue therapy when such events occur

              May impair vitamin B12 or calcium intake/absorption; monitor B12 serum concentrations periodically with long-term therapy

              Not indicated for use in patients with type 1 diabetes mellitus that are insulin dependent due to lack of efficacy

              Withhold in patients with dehydration and/or prerenal azotemia

              Conclusive evidence of macrovascular risk reduction with metformin not established

              Clinical recommendations based upon the patient’s renal function

              • Before initiating therapy, obtain an eGFR
              • Initiation of therapy is not recommended in patients with eGFR between 30 –45 mL/minute/1.73 m²
              • Obtain an eGFR at least annually in all patients receiving therapy
              • In patients at increased risk for development of renal impairment (e.g., the elderly), renal function should be assessed more frequently
              • If eGFR later falls below 45 mL/minute/1.73 m², assess benefit and risk of continuing therapy

              Iodinated contrast imaging procedures

              • Discontinue metformin at the time of or before an iodinated contrast imaging procedure in patients with an eGFR between 30-60 mL/minute/1.73 m²; in patients with a history of liver disease, alcoholism, or heart failure; or in patients who will be administered intra-arterial iodinate contrast
              • Reevaluate eGFR 48 hr after the imaging procedure; restart metformin if renal function is stable
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              Pregnancy & Lactation

              Pregnancy

              Limited data with in pregnant women are not sufficient to determine drug-associated risk for major birth defects or miscarriage; published studies with metformin use during pregnancy have not reported a clear association with metformin and major birth defect or miscarriage risk; poorly-controlled diabetes mellitus in pregnancy increases maternal risk for diabetic ketoacidosis, pre-eclampsia, spontaneous abortions, preterm delivery, stillbirth and delivery complications; poorly controlled diabetes mellitus increases the fetal risk for major birth defects, stillbirth, and macrosomia related morbidity

              Human data

              • Published data from post-marketing studies have not reported clear association with metformin and major birth defects, miscarriage, or adverse maternal or fetal outcomes when used during pregnancy; however, these studies cannot definitely establish absence of any metformin-associated risk because of methodological limitations, including small sample size and inconsistent comparator groups

              Animal data

              • Metformin hydrochloride did not adversely affect development outcomes when administered to pregnant rats and rabbits at doses up to 600 mg/kg/day; this represents exposure of about 2 and 5 times a 2550 mg clinical dose based on body surface area comparisons for rats and rabbits, respectively; determination of fetal concentrations demonstrated a partial placental barrier to metformin

              Reproduction potential

              • Discuss potential for unintended pregnancy with premenopausal women as therapy may result in ovulation in some anovulatory women

              Lactation

              Limited published studies report that metformin is present in human milk; however, there is insufficient information to determine effects of metformin on breastfed infant and no available information on effects of metformin on milk production; therefore, developmental and health benefits of breastfeeding should be considered along with mother’s clinical need for therapy and any potential adverse effects on breastfed child from therapy or from the underlying maternal condition

              Pregnancy Categories

              A: Generally acceptable. Controlled studies in pregnant women show no evidence of fetal risk.

              B: May be acceptable. Either animal studies show no risk but human studies not available or animal studies showed minor risks and human studies done and showed no risk.

              C: Use with caution if benefits outweigh risks. Animal studies show risk and human studies not available or neither animal nor human studies done.

              D: Use in LIFE-THREATENING emergencies when no safer drug available. Positive evidence of human fetal risk.

              X: Do not use in pregnancy. Risks involved outweigh potential benefits. Safer alternatives exist.

              NA: Information not available.

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              Pharmacology

              Mechanism of Action

              Decreases hepatic glucose production; decreases GI glucose absorption; increases target cell insulin sensitivity

              Absorption

              Bioavailability: 50-60%

              Peak plasma time

              • Regular-release: 2-3 hr
              • Extended-release: 4-8 hr

              Distribution

              Protein bound: Minimal

              Vd: 650 L (regular-release)

              Metabolism

              Metabolism: Not by liver

              Elimination

              Half-Life: 4-9 hr

              Dialyzable: Yes (hemodialysis)

              Renal clearance: 450-540 mL/min (regular-release)

              Excretion: Urine (90%, by tubular secretion)

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              Administration

              Oral Suspension Preparation (Riomet ER)

              Remove bottle containing drug pellets and drug diluent bottle along with measuring cup from the box

              Do not use if drug is expired, damaged, or defective

              Pour contents of bottle containing drug pellets in to the drug diluent bottle and discard the empty pellet bottle

              Shake bottle continuously in an up and down direction for at least 2 full min; reconstituted suspension is 500 mg/5 mL

              Oral Administration

              Take with an evening meal

              Oral solution or suspension: Measure dose in the provided dosing cup

              Extended-release tablets: Swallow tablets whole and never crush, cut, or chew

              Missed dose

              • Do not to take 2 doses the same day and to resume the usual dose with the next schedule dose

              Storage

              Tablets

              • Store at 20-25ºC (68-77ºF); excursions permitted to 15-30ºC (59-86ºF)

              Oral solution (Riomet)

              • Store at 15-30ºC (59-86ºF)

              Oral suspension (Riomet ER)

              • Unused bottle: Store at 20-25ºC (68-77ºF)
              • Reconstituted oral suspension: Store at 20-25°C (68-77ºF) for up to 100 days; do not repackage
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              Images

              BRAND FORM. UNIT PRICE PILL IMAGE
              Riomet oral
              -
              500 mg/5 mL solution
              Riomet oral
              -
              500 mg/5 mL solution
              Riomet oral
              -
              500 mg/5 mL solution
              metformin oral
              -
              750 mg tablet
              metformin oral
              -
              500 mg tablet
              metformin oral
              -
              500 mg tablet
              metformin oral
              -
              500 mg tablet
              metformin oral
              -
              1,000 mg tablet
              metformin oral
              -
              1,000 mg tablet
              metformin oral
              -
              850 mg tablet
              metformin oral
              -
              500 mg tablet
              metformin oral
              -
              500 mg tablet
              metformin oral
              -
              750 mg tablet
              metformin oral
              -
              850 mg tablet
              metformin oral
              -
              500 mg tablet
              metformin oral
              -
              750 mg tablet
              metformin oral
              -
              1,000 mg tablet
              metformin oral
              -
              850 mg tablet
              metformin oral
              -
              500 mg tablet
              metformin oral
              -
              500 mg tablet
              metformin oral
              -
              500 mg tablet
              metformin oral
              -
              1,000 mg tablet
              metformin oral
              -
              850 mg tablet
              metformin oral
              -
              1,000 mg tablet
              metformin oral
              -
              500 mg tablet
              metformin oral
              -
              500 mg tablet
              metformin oral
              -
              1,000 mg tablet
              metformin oral
              -
              500 mg tablet
              metformin oral
              -
              1,000 mg tablet
              metformin oral
              -
              500 mg tablet
              metformin oral
              -
              750 mg tablet
              metformin oral
              -
              500 mg tablet
              metformin oral
              -
              1,000 mg tablet
              metformin oral
              -
              500 mg tablet
              metformin oral
              -
              500 mg tablet
              metformin oral
              -
              1,000 mg tablet
              metformin oral
              -
              500 mg tablet
              metformin oral
              -
              750 mg tablet
              metformin oral
              -
              850 mg tablet
              metformin oral
              -
              1,000 mg tablet
              metformin oral
              -
              500 mg tablet
              metformin oral
              -
              750 mg tablet
              metformin oral
              -
              500 mg tablet
              metformin oral
              -
              1,000 mg tablet
              metformin oral
              -
              850 mg tablet
              metformin oral
              -
              500 mg tablet
              metformin oral
              -
              500 mg tablet
              metformin oral
              -
              850 mg tablet
              metformin oral
              -
              500 mg tablet
              metformin oral
              -
              1,000 mg tablet
              metformin oral
              -
              850 mg tablet
              metformin oral
              -
              850 mg tablet
              metformin oral
              -
              500 mg tablet
              metformin oral
              -
              1,000 mg tablet
              metformin oral
              -
              500 mg tablet
              metformin oral
              -
              1,000 mg tablet
              metformin oral
              -
              850 mg tablet
              metformin oral
              -
              500 mg tablet
              metformin oral
              -
              500 mg tablet
              metformin oral
              -
              1,000 mg tablet
              metformin oral
              -
              500 mg tablet
              metformin oral
              -
              750 mg tablet
              metformin oral
              -
              500 mg tablet
              metformin oral
              -
              750 mg tablet
              metformin oral
              -
              500 mg tablet
              metformin oral
              -
              1,000 mg tablet
              metformin oral
              -
              500 mg tablet
              metformin oral
              -
              750 mg tablet
              metformin oral
              -
              500 mg tablet
              metformin oral
              -
              500 mg tablet
              metformin oral
              -
              500 mg tablet
              metformin oral
              -
              750 mg tablet
              metformin oral
              -
              850 mg tablet
              metformin oral
              -
              1,000 mg tablet
              metformin oral
              -
              1,000 mg tablet
              metformin oral
              -
              500 mg tablet
              metformin oral
              -
              1,000 mg tablet
              metformin oral
              -
              500 mg tablet
              metformin oral
              -
              500 mg tablet
              metformin oral
              -
              1,000 mg tablet
              metformin oral
              -
              850 mg tablet
              metformin oral
              -
              750 mg tablet
              metformin oral
              -
              1,000 mg tablet
              metformin oral
              -
              500 mg tablet
              Glumetza oral
              -
              500 mg tablet
              Glumetza oral
              -
              1,000 mg tablet

              Copyright © 2010 First DataBank, Inc.

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              Patient Handout

              Patient Education
              metformin oral

              METFORMIN - ORAL

              (met-FOR-min)

              COMMON BRAND NAME(S): Glucophage

              WARNING: Rarely, too much metformin can build up in the body and cause a serious (sometimes fatal) condition called lactic acidosis. Lactic acidosis is more likely if you are an older adult, if you have kidney or liver disease, dehydration, heart failure, heavy alcohol use, if you have surgery, if you have X-ray or scanning procedures that use iodinated contrast, or if you are using certain drugs. For some conditions, your doctor may tell you to stop taking this medication for a short time. Ask your doctor or pharmacist for more details.Stop taking this medication and get medical help right away if you have any symptoms of lactic acidosis, such as unusual tiredness, dizziness, severe drowsiness, chills, blue/cold skin, muscle pain, fast/difficult breathing, slow/irregular heartbeat, or stomach pain with nausea/vomiting/diarrhea.

              USES: Metformin is used with a proper diet and exercise program and possibly with other medications to control high blood sugar. It is used in patients with type 2 diabetes. Controlling high blood sugar helps prevent kidney damage, blindness, nerve problems, loss of limbs, and sexual function problems. Proper control of diabetes may also lessen your risk of a heart attack or stroke. Metformin works by helping to restore your body's proper response to the insulin you naturally produce. It also decreases the amount of sugar that your liver makes and that your stomach/intestines absorb.

              HOW TO USE: Read the Patient Information Leaflet if available from your pharmacist before you start taking metformin and each time you get a refill. If you have any questions, consult your doctor or pharmacist.Take this medication by mouth as directed by your doctor, usually 1-3 times a day with meals. Drink plenty of fluids while taking this medication unless otherwise directed by your doctor.The dosage is based on your medical condition, response to treatment, and other medications you may be taking. Be sure to tell your doctor and pharmacist about all the products you use (including prescription drugs, nonprescription drugs, and herbal products). To reduce your risk of side effects (such as upset stomach), your doctor may direct you to start this medication at a low dose and gradually increase your dose. Follow your doctor's instructions carefully.Take this medication regularly in order to get the most benefit from it. Remember to use it at the same times each day.If you are already taking another diabetes drug (such as chlorpropamide), follow your doctor's directions carefully for stopping/continuing the old drug and starting metformin.Check your blood sugar regularly as directed by your doctor. Keep track of the results, and share them with your doctor. Tell your doctor if your blood sugar measurements are too high or too low. Your dosage/treatment may need to be changed.

              SIDE EFFECTS: See also Warning section.Nausea, vomiting, stomach upset, diarrhea, weakness, or a metallic taste in the mouth may occur. If any of these effects persist or worsen, tell your doctor or pharmacist promptly. If stomach symptoms return later (after taking the same dose for several days or weeks), tell your doctor right away. Stomach symptoms that occur after the first days of your treatment may be signs of lactic acidosis.Remember that this medication has been prescribed because your doctor has judged that the benefit to you is greater than the risk of side effects. Many people using this medication do not have serious side effects.Metformin does not usually cause low blood sugar (hypoglycemia). Low blood sugar may occur if this drug is prescribed with other diabetes medications. Talk with your doctor or pharmacist about whether the dose of your other diabetes medication(s) needs to be lowered.Symptoms of low blood sugar include sudden sweating, shaking, fast heartbeat, hunger, blurred vision, dizziness, or tingling hands/feet. It is a good habit to carry glucose tablets or gel to treat low blood sugar. If you don't have these reliable forms of glucose, rapidly raise your blood sugar by eating a quick source of sugar such as table sugar, honey, or candy, or drink fruit juice or non-diet soda. Tell your doctor about the reaction right away. Low blood sugar is more likely if you drink large amounts of alcohol, do unusually heavy exercise, or do not consume enough calories from food. To help prevent low blood sugar, eat meals on a regular schedule, and do not skip meals. Check with your doctor or pharmacist to find out what you should do if you miss a meal.Symptoms of high blood sugar (hyperglycemia) include thirst, increased urination, confusion, drowsiness, flushing, rapid breathing, and fruity breath odor. If these symptoms occur, tell your doctor right away. Your doctor may need to adjust your diabetes medication(s).Stop taking this medication and tell your doctor right away if this very serious side effect occurs: lactic acidosis (see Warning section).A very serious allergic reaction to this drug is rare. However, get medical help right away if you notice any of the following symptoms of a serious allergic reaction: rash, itching/swelling (especially of the face/tongue/throat), severe dizziness, trouble breathing.This is not a complete list of possible side effects. If you notice other effects not listed above, contact your doctor or pharmacist.In the US -Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088 or at www.fda.gov/medwatch.In Canada - Call your doctor for medical advice about side effects. You may report side effects to Health Canada at 1-866-234-2345.

              PRECAUTIONS: See also Warning section.Before taking this medication, tell your doctor or pharmacist if you are allergic to metformin; or if you have any other allergies. This product may contain inactive ingredients, which can cause allergic reactions or other problems. Talk to your pharmacist for more details.Before using this medication, tell your doctor or pharmacist your medical history, especially of: severe breathing problems (such as obstructive lung disease, severe asthma), blood problems (such as anemia, vitamin B12 deficiency), kidney disease, liver disease.Before having surgery or any X-ray/scanning procedure using iodinated contrast, tell your doctor or dentist about all the products you use (including prescription drugs, nonprescription drugs, and herbal products). You may need to stop this medication for a short time for the surgery/procedure. Ask your doctor or dentist for instructions before your surgery/procedure.You may experience blurred vision, dizziness, or drowsiness due to extremely low or high blood sugar. Do not drive, use machinery, or do any activity that requires alertness or clear vision until you are sure you can perform such activities safely.Limit alcohol while using this medication because it can increase your risk of lactic acidosis and developing low blood sugar.High fever, "water pills" (diuretics such as hydrochlorothiazide), too much sweating, diarrhea, or vomiting may cause dehydration and increase your risk of lactic acidosis. Stop taking this medication and tell your doctor right away if you have prolonged diarrhea or vomiting. Be sure to drink enough fluids to prevent dehydration unless your doctor directs you otherwise.It may be harder to control your blood sugar when your body is stressed (such as due to fever, infection, injury, or surgery). Consult your doctor because increased stress may require a change in your treatment plan, medications, or blood sugar testing.Older adults may be at greater risk for side effects such as low blood sugar or lactic acidosis.During pregnancy, this medication should be used only when clearly needed. Discuss the risks and benefits with your doctor. Your doctor may direct you to use insulin instead of this product during your pregnancy. Follow your doctor's instructions carefully.Metformin can cause changes in the menstrual cycle (promote ovulation) and increase the risk of becoming pregnant. Consult your doctor or pharmacist about the use of reliable birth control while using this medication.Metformin passes into breast milk in small amounts. Consult your doctor before breast-feeding.

              DRUG INTERACTIONS: Drug interactions may change how your medications work or increase your risk for serious side effects. This document does not contain all possible drug interactions. Keep a list of all the products you use (including prescription/nonprescription drugs and herbal products) and share it with your doctor and pharmacist. Do not start, stop, or change the dosage of any medicines without your doctor's approval.Beta-blocker medications (such as metoprolol, propranolol, glaucoma eye drops such as timolol) may prevent the fast/pounding heartbeat you would usually feel when your blood sugar falls too low (hypoglycemia). Other symptoms of low blood sugar, such as dizziness, hunger, or sweating, are unaffected by these drugs.Many drugs can affect your blood sugar, making it harder to control. Before you start, stop, or change any medication, talk with your doctor or pharmacist about how the medication may affect your blood sugar. Check your blood sugar regularly as directed and share the results with your doctor. Tell your doctor right away if you have symptoms of high or low blood sugar. (See also Side Effects section.) Your doctor may need to adjust your diabetes medication, exercise program, or diet.

              OVERDOSE: If someone has overdosed and has serious symptoms such as passing out or trouble breathing, call 911. Otherwise, call a poison control center right away. US residents can call their local poison control center at 1-800-222-1222. Canada residents can call a provincial poison control center. Overdose can cause lactic acidosis. Symptoms of overdose may include: severe drowsiness, severe nausea/vomiting/diarrhea, rapid breathing, slow/irregular heartbeat.

              NOTES: Do not share this medication with others.Attend a diabetes education program to learn more about how to manage your diabetes with medications, diet, exercise, and regular medical exams.Learn the symptoms of high and low blood sugar and how to treat low blood sugar. Check your blood sugar regularly as directed and share the results with your doctor.Lab and/or medical tests (such as kidney function, liver function, blood sugar, hemoglobin A1c, complete blood counts) should be done before you start taking this medication and while you are taking it. Keep all medical and lab appointments. Consult your doctor for more details.

              MISSED DOSE: If you miss a dose, take it as soon as you remember with food. If it is near the time of the next dose, skip the missed dose. Take your next dose at the regular time. Do not double the dose to catch up.

              STORAGE: Store at room temperature away from light and moisture. Do not store in the bathroom. Keep all medications away from children and pets.Do not flush medications down the toilet or pour them into a drain unless instructed to do so. Properly discard this product when it is expired or no longer needed. Consult your pharmacist or local waste disposal company for more details about how to safely discard your product.

              MEDICAL ALERT: Your condition can cause complications in a medical emergency. For information about enrolling in MedicAlert, call 1-888-633-4298 (US) or 1-800-668-1507 (Canada).

              Information last revised August 2021. Copyright(c) 2021 First Databank, Inc.

              IMPORTANT: HOW TO USE THIS INFORMATION: This is a summary and does NOT have all possible information about this product. This information does not assure that this product is safe, effective, or appropriate for you. This information is not individual medical advice and does not substitute for the advice of your health care professional. Always ask your health care professional for complete information about this product and your specific health needs.

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              Formulary

              FormularyPatient Discounts

              Adding plans allows you to compare formulary status to other drugs in the same class.

              To view formulary information first create a list of plans. Your list will be saved and can be edited at any time.

              Adding plans allows you to:

              • View the formulary and any restrictions for each plan.
              • Manage and view all your plans together – even plans in different states.
              • Compare formulary status to other drugs in the same class.
              • Access your plan list on any device – mobile or desktop.

              The above information is provided for general informational and educational purposes only. Individual plans may vary and formulary information changes. Contact the applicable plan provider for the most current information.

              Tier Description
              1 This drug is available at the lowest co-pay. Most commonly, these are generic drugs.
              2 This drug is available at a middle level co-pay. Most commonly, these are "preferred" (on formulary) brand drugs.
              3 This drug is available at a higher level co-pay. Most commonly, these are "non-preferred" brand drugs.
              4 This drug is available at a higher level co-pay. Most commonly, these are "non-preferred" brand drugs or specialty prescription products.
              5 This drug is available at a higher level co-pay. Most commonly, these are "non-preferred" brand drugs or specialty prescription products.
              6 This drug is available at a higher level co-pay. Most commonly, these are "non-preferred" brand drugs or specialty prescription products.
              NC NOT COVERED – Drugs that are not covered by the plan.
              Code Definition
              PA Prior Authorization
              Drugs that require prior authorization. This restriction requires that specific clinical criteria be met prior to the approval of the prescription.
              QL Quantity Limits
              Drugs that have quantity limits associated with each prescription. This restriction typically limits the quantity of the drug that will be covered.
              ST Step Therapy
              Drugs that have step therapy associated with each prescription. This restriction typically requires that certain criteria be met prior to approval for the prescription.
              OR Other Restrictions
              Drugs that have restrictions other than prior authorization, quantity limits, and step therapy associated with each prescription.
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              Medscape prescription drug monographs are based on FDA-approved labeling information, unless otherwise noted, combined with additional data derived from primary medical literature.