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

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            Adverse Effects

            >10%

            Diarrhea, immediate-release product (53%)

            Nausea/vomiting, immediate-release product (25%)

            1-10%

            Diarrhea, extended-release product (10%)

            Nausea/vomiting, extended-release product (7%)

            Low serum vitamin B-12 (7%)

            Abdominal pain (1-5%)

            Constipation (1-5%)

            Abdomen distention (1-5%)

            Dyspepsia/heartburn (1-5%)

            Flatulence (1-5%)

            Dizziness (1-5%)

            Headache (1-5%)

            Upper respiratory infection (1-5%)

            Taste disturbance (1-5%)

            Postmarketing Reports H3

            Cholestatic, hepatocellular, and mixed hepatocellular liver injury

            Frequency Not Defined

            Lactic acidosis

            Hypoglycemia

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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
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            500 mg/5 mL solution
            Riomet oral
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            500 mg/5 mL solution
            Riomet oral
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            500 mg/5 mL solution
            metformin oral
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            750 mg tablet
            metformin oral
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            500 mg tablet
            metformin oral
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            1,000 mg tablet
            metformin oral
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            850 mg tablet
            metformin oral
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            500 mg tablet
            metformin oral
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            500 mg tablet
            metformin oral
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            500 mg tablet
            metformin oral
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            500 mg tablet
            metformin oral
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            850 mg tablet
            metformin oral
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            500 mg tablet
            metformin oral
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            1,000 mg tablet
            metformin oral
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            850 mg tablet
            metformin oral
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            750 mg tablet
            metformin oral
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            500 mg tablet
            metformin oral
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            1,000 mg tablet
            metformin oral
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            850 mg tablet
            metformin oral
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            500 mg tablet
            metformin oral
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            750 mg tablet
            metformin oral
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            1,000 mg tablet
            metformin oral
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            500 mg tablet
            metformin oral
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            metformin oral
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            1,000 mg tablet
            metformin oral
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            500 mg tablet
            metformin oral
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            500 mg tablet
            metformin oral
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            500 mg tablet
            metformin oral
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            850 mg tablet
            metformin oral
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            500 mg tablet
            metformin oral
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            500 mg tablet
            metformin oral
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            750 mg tablet
            metformin oral
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            1,000 mg tablet
            metformin oral
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            1,000 mg tablet
            metformin oral
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            500 mg tablet
            metformin oral
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            500 mg tablet
            metformin oral
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            500 mg tablet
            metformin oral
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            500 mg tablet
            metformin oral
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            1,000 mg tablet
            metformin oral
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            500 mg tablet
            metformin oral
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            500 mg tablet
            metformin oral
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            1,000 mg tablet
            metformin oral
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            500 mg tablet
            metformin oral
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            500 mg tablet
            metformin oral
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            850 mg tablet
            metformin oral
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            1,000 mg tablet
            metformin oral
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            500 mg tablet
            metformin oral
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            1,000 mg tablet
            metformin oral
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            1,000 mg tablet
            metformin oral
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            1,000 mg tablet
            metformin oral
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            1,000 mg tablet
            metformin oral
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            750 mg tablet
            metformin oral
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            500 mg tablet
            metformin oral
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            1,000 mg tablet
            metformin oral
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            500 mg tablet
            metformin oral
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            850 mg tablet
            metformin oral
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            750 mg tablet
            metformin oral
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            1,000 mg tablet
            metformin oral
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            500 mg tablet
            metformin oral
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            750 mg tablet
            metformin oral
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            500 mg tablet
            metformin oral
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            750 mg tablet
            metformin oral
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            500 mg tablet
            metformin oral
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            500 mg tablet
            metformin oral
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            1,000 mg tablet
            metformin oral
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            500 mg tablet
            metformin oral
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            500 mg tablet
            metformin oral
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            500 mg tablet
            metformin oral
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            500 mg tablet
            metformin oral
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            850 mg tablet
            metformin oral
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            750 mg tablet
            metformin oral
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            500 mg tablet
            metformin oral
            -
            1,000 mg tablet
            metformin oral
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            500 mg tablet
            metformin oral
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            1,000 mg tablet
            metformin oral
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            500 mg tablet
            metformin oral
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            500 mg tablet
            metformin oral
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            750 mg tablet
            metformin oral
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            750 mg tablet
            metformin oral
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            500 mg tablet
            metformin oral
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            850 mg tablet
            metformin oral
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            1,000 mg tablet
            metformin oral
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            500 mg tablet
            metformin oral
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            850 mg tablet
            metformin oral
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            500 mg tablet
            metformin oral
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            1,000 mg tablet
            Glumetza oral
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            1,000 mg tablet
            Glumetza oral
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            500 mg tablet

            Copyright © 2010 First DataBank, Inc.

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            Patient Handout

            Patient Education
            metformin oral

            METFORMIN EXTENDED-RELEASE SUSPENSION - ORAL

            (met-FOR-min)

            COMMON BRAND NAME(S): Riomet ER

            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 in people 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 and Instructions for Use if available from your pharmacist before you start taking metformin and each time you get a refill. If you have any questions, ask your doctor or pharmacist.Take this medication by mouth as directed by your doctor, usually once daily with the evening meal. Drink plenty of fluids while taking this medication unless otherwise directed by your doctor. Do not take this medication at the same time with alcohol or with medications that contain alcohol. Doing so can release all of the drug at once, increasing the risk of side effects.Shake the bottle well before each dose. Carefully measure the dose using a special measuring device/spoon. Do not use a household spoon because you may not get the correct dose.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 to get the most benefit from it. Remember to use it at the same time 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.Tell your doctor if your condition does not get better or if it gets worse (your blood sugar is too high or too low).

            SIDE EFFECTS: See also Warning section.Nausea, vomiting, stomach upset, diarrhea, gas, weakness, or a metallic taste in the mouth may occur. If any of these effects last or get worse, 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, or if you do not consume enough calories from food, or if you do unusually heavy exercise. 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 right away about the reaction and the use of this product. 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 increased thirst/urination. If these symptoms occur, tell your doctor right away. Your dosage may need to be increased.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 symptoms of a serious allergic reaction, including: 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: breathing problems (such as obstructive lung disease, 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 developing low blood sugar or lactic acidosis.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 this 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.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. 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 in original bottle at room temperature away from light and moisture. Do not store in the bathroom. Discard any unused portion after 100 days. 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.

            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) 2022 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.
            Additional Offers
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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.