magnesium oxide (OTC)

Brand and Other Names:Mag-Ox 400, Uro-Mag, more...Mag-Caps
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Dosing & Uses

AdultPediatric

Dosage Forms & Strengths

capsule

  • 140mg (equivalent to 84.5mg [6.93mEq] elemental magnesium)

tablet

  • 400mg (equivalent to 240mg [20mEq] elemental magnesium)

Recommended Daily Intake (Elemental Mg)

Females

  • 19-30 yr: 310 mg/day PO
  • 19-30 yr (pregnant): 350 mg/day PO
  • >31 yr: 320 mg/day PO
  • >31 yr (pregnant): 360 mg/day PO

Males

  • 19-30 yr: 400 mg/day PO
  • >31 yr: 420 mg/day PO

Magnesium Supplementation

Tablet (Mag-Ox): 1-2 tablets PO qDay

Capsule (Uro-Mag): 1-5 capsules PO qDay

Antacid

Tablet (Mag-Ox): 1 tablet PO qDay or q12hr; not to exceed 2 tablets/day

Renal Impairment

CrCl <30 mL/min: Caution; monitor for hypermagnesemia

Administration

Take with food

Dosage Forms & Strengths

capsule

  • 140mg (equivalent to 84.5mg [6.93mEq] elemental magnesium)

tablet

  • 400mg (equivalent to 240mg [20mEq] elemental magnesium)

Recommended Daily Intake (Elemental Mg)

1-3 years: 80 mg/day PO

4-8 years: 130 mg/day PO

9-13 years: 240 mg/day PO

14-18 years

  • Females: 360 mg/day PO
  • Pregnant females: 400 mg/day PO
  • Males: 410 mg/day PO

Renal Impairment

CrCl <30 mL/min: Caution; monitor for hypermagnesemia

Administration

Take with food

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Interactions

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              Serious - Use Alternative (12)

              • atazanavir

                magnesium oxide will decrease the level or effect of atazanavir by increasing gastric pH. Applies only to oral form of both agents. Avoid or Use Alternate Drug. Atazanavir solubility decreases as pH increases. Reduced plasma concentrations of atazanavir are expected if antacids or buffered medications are coadministered. Administer atazanavir 2 hr before or 1 hr after these medications.

              • baloxavir marboxil

                magnesium oxide will decrease the level or effect of baloxavir marboxil by cation binding in GI tract. Avoid or Use Alternate Drug. Baloxavir may bind to polyvalent cations resulting in decreased absorption. Studies in monkeys showed concurrent use with calcium, aluminum, or iron caused significantly decreased plasma levels. Human studies not conducted.

              • demeclocycline

                magnesium oxide decreases levels of demeclocycline by inhibition of GI absorption. Applies only to oral form of both agents. Avoid or Use Alternate Drug.

              • dolutegravir

                magnesium oxide will decrease the level or effect of dolutegravir by cation binding in GI tract. Avoid or Use Alternate Drug. Administer dolutegravir 2 hr before or 6 hr after taking medications containing polyvalent cations

              • doxycycline

                magnesium oxide decreases levels of doxycycline by inhibition of GI absorption. Applies only to oral form of both agents. Avoid or Use Alternate Drug.

              • eltrombopag

                magnesium oxide decreases levels of eltrombopag by inhibition of GI absorption. Applies only to oral form of both agents. Contraindicated. Separate by at least 4 hours.

              • infigratinib

                magnesium oxide will decrease the level or effect of infigratinib by inhibition of GI absorption. Applies only to oral form of both agents. Avoid or Use Alternate Drug. If use with an acid-reducing agent cannot be avoided, administer infigratinib 2 hr before and after administration of a locally-acting antacid.

              • minocycline

                magnesium oxide decreases levels of minocycline by inhibition of GI absorption. Applies only to oral form of both agents. Avoid or Use Alternate Drug.

              • oxytetracycline

                magnesium oxide decreases levels of oxytetracycline by inhibition of GI absorption. Applies only to oral form of both agents. Avoid or Use Alternate Drug.

              • ponatinib

                magnesium oxide decreases levels of ponatinib by increasing gastric pH. Applies only to oral form of both agents. Avoid or Use Alternate Drug.

              • sotorasib

                magnesium oxide will decrease the level or effect of sotorasib by inhibition of GI absorption. Applies only to oral form of both agents. Avoid or Use Alternate Drug. If use with an acid-reducing agent cannot be avoided, administer sotorasib 4 hr before or 10 hr after administration of a locally-acting antacid.

              • tetracycline

                magnesium oxide decreases levels of tetracycline by inhibition of GI absorption. Applies only to oral form of both agents. Avoid or Use Alternate Drug.

              Monitor Closely (34)

              • acalabrutinib

                magnesium oxide decreases levels of acalabrutinib by increasing gastric pH. Applies only to oral form of both agents. Modify Therapy/Monitor Closely. Acalabrutinib solubility decreases with increasing gastric pH. Separate dosing by at least 2 hr between administration of antacids and acalabrutinib.

              • bictegravir

                magnesium oxide will decrease the level or effect of bictegravir by cation binding in GI tract. Modify Therapy/Monitor Closely. Bictegravir can be taken under fasting conditions 2 hr before antacids containing Al, Mg, or Ca. Routine administration of bictegravir simultaneously with, or 2 hr after, antacids containing Al, Mg, or Ca is not recommended.

              • bosutinib

                magnesium oxide decreases levels of bosutinib by increasing gastric pH. Applies only to oral form of both agents. Use Caution/Monitor. Bosutinib displays pH-dependent solubility; may use short-acting antacids with administration separated by 2 hr.

              • budesonide

                magnesium oxide decreases effects of budesonide by increasing gastric pH. Applies only to oral form of both agents. Modify Therapy/Monitor Closely. Enteric-coated budesonide dissolves at pH >5.5. Also, dissolution of extended-release budesonide tablets is pH dependent. Coadministration with drugs that increase gastric pH may cause these budesonide products to prematurely dissolve, and possibly affect release properties and absorption of the drug in the duodenum.

              • cabotegravir

                magnesium oxide will decrease the level or effect of cabotegravir by cation binding in GI tract. Modify Therapy/Monitor Closely. Administer antacid products at least 2 hr before or 4 hr after taking oral cabotegravir.

              • chloroquine

                magnesium oxide will decrease the level or effect of chloroquine by cation binding in GI tract. Use Caution/Monitor. Separate doses by at least 4 hr

              • ciprofloxacin

                magnesium oxide decreases levels of ciprofloxacin by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor. Separate by 2 hours.

              • crizotinib

                magnesium oxide decreases levels of crizotinib by increasing gastric pH. Applies only to oral form of both agents. Use Caution/Monitor. Drugs that elevate the gastric pH may decrease the solubility of crizotinib and subsequently reduce its bioavailability. However, no formal studies have been conducted. .

              • dabrafenib

                magnesium oxide will decrease the level or effect of dabrafenib by increasing gastric pH. Applies only to oral form of both agents. Use Caution/Monitor. Drugs that alter upper GI tract pH (eg, PPIs, H2-blockers, antacids) may decrease dabrafenib solubility and reduce its bioavailability

              • deferiprone

                magnesium oxide decreases levels of deferiprone by enhancing GI absorption. Applies only to oral form of both agents. Modify Therapy/Monitor Closely. Deferiprone may bind polyvalent cations (eg, iron, aluminum, and zinc), separate administration by at least 4 hr between deferiprone and other medications (eg, antacids), or supplements containing these polyvalent cations.

              • delafloxacin

                magnesium oxide will decrease the level or effect of delafloxacin by cation binding in GI tract. Modify Therapy/Monitor Closely. Oral delafloxacin form chelates with alkaline earth and transition metal cations. Administer oral delafloxacin at least 2 hr before or 6 hr after these agents.

              • elvitegravir

                magnesium oxide will decrease the level or effect of elvitegravir by cation binding in GI tract. Modify Therapy/Monitor Closely. Elvitegravir plasma concentrations are lower with antacids due to the formation of ionic complexes in the GI tract and not due to changes in gastric pH; separate dose from antacid by at least 2 hr

              • elvitegravir/cobicistat/emtricitabine/tenofovir DF

                magnesium oxide decreases levels of elvitegravir/cobicistat/emtricitabine/tenofovir DF by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor. Separate administration from antacids by 2 hr.

              • fleroxacin

                magnesium oxide decreases levels of fleroxacin by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor. Separate by 2 hours.

              • gefitinib

                magnesium oxide decreases levels of gefitinib by increasing gastric pH. Applies only to oral form of both agents. Use Caution/Monitor. Separate gefitinib and antacid doses by at least 6 hr.

              • gemifloxacin

                magnesium oxide decreases levels of gemifloxacin by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor. Separate by 2 hours.

              • ledipasvir/sofosbuvir

                magnesium oxide decreases levels of ledipasvir/sofosbuvir by Other (see comment). Use Caution/Monitor. Comment: Ledipasvir solubility decreases as pH increases; drugs that increase gastric pH are expected to decrease levels of ledipasvir; separate antacid and ledipasivr/sofosbuvir administration by 4 hr.

              • levofloxacin

                magnesium oxide decreases levels of levofloxacin by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor. Separate by 2 hours.

              • lisdexamfetamine

                magnesium oxide will increase the level or effect of lisdexamfetamine by passive renal tubular reabsorption - basic urine. Use Caution/Monitor.

              • methylphenidate

                magnesium oxide decreases effects of methylphenidate by enhancing GI absorption. Applies only to oral form of both agents. Modify Therapy/Monitor Closely. Since the characteristics of methylphenidate extended release capsules (Ritalin LA) are pH dependent, coadministration of antacids or acid suppressants could alter the release of methylphenidate. Consider separating the administration of the antacid and the methylphenidate extended-release capsules may be avoided.

              • moxifloxacin

                magnesium oxide decreases levels of moxifloxacin by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor. Separate by 2 hours.

              • neratinib

                magnesium oxide will decrease the level or effect of neratinib by increasing gastric pH. Applies only to oral form of both agents. Modify Therapy/Monitor Closely. Separate antacid and neratinib dosing by 3 hr.

              • nilotinib

                magnesium oxide decreases levels of nilotinib by increasing gastric pH. Applies only to oral form of both agents. Modify Therapy/Monitor Closely. Avoid this interaction by administering antacids 2 hr after or 2 hr before nilotinib.

              • ofloxacin

                magnesium oxide decreases levels of ofloxacin by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor. Separate by 2 hours.

              • omadacycline

                magnesium oxide will decrease the level or effect of omadacycline by inhibition of GI absorption. Applies only to oral form of both agents. Modify Therapy/Monitor Closely. Multivalent cation-containing products may impair absorption of tetracyclines, which may decrease its efficacy. Separate dosing of tetracyclines from these products.

              • penicillamine

                magnesium oxide decreases levels of penicillamine by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor. Separate by 2 hours.

              • pexidartinib

                magnesium oxide will decrease the level or effect of pexidartinib by inhibition of GI absorption. Applies only to oral form of both agents. Modify Therapy/Monitor Closely. Separate pexidartinib by 2 hr before or after taking a locally-acting antacid.

              • rilpivirine

                magnesium oxide decreases levels of rilpivirine by increasing gastric pH. Applies only to oral form of both agents. Modify Therapy/Monitor Closely. Coadministration of antacids with rilpivirine may cause significant decreases in rilpivirine plasma concentrations because of increased gastric pH. If antacids must be administered, they should be given at least 2 hr before or at least 4 hr after rilpivirine. For the combination product dolutegravir/rilpivirine, antacids should be given at least 4 hr before or at least 6 hr afterwards.

              • riociguat

                magnesium oxide decreases levels of riociguat by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor. Separate administration by at least 1 hour.

              • sarecycline

                magnesium oxide will decrease the level or effect of sarecycline by inhibition of GI absorption. Applies only to oral form of both agents. Modify Therapy/Monitor Closely. Multivalent cation-containing products may impair absorption of tetracyclines, which may decrease its efficacy. Separate dosing of tetracyclines from these products.

              • sodium sulfate/?magnesium sulfate/potassium chloride

                sodium sulfate/?magnesium sulfate/potassium chloride increases toxicity of magnesium oxide by Other (see comment). Use Caution/Monitor. Comment: Coadministration with medications that cause fluid and electrolyte abnormalities may increase the risk of adverse events of seizure, arrhythmias, and renal impairment.

              • sodium sulfate/potassium sulfate/magnesium sulfate

                sodium sulfate/potassium sulfate/magnesium sulfate increases toxicity of magnesium oxide by Other (see comment). Use Caution/Monitor. Comment: Coadministration with medications that cause fluid and electrolyte abnormalities may increase the risk of adverse events of seizure, arrhythmias, and renal impairment.

              • sofosbuvir/velpatasvir

                magnesium oxide will decrease the level or effect of sofosbuvir/velpatasvir by increasing gastric pH. Applies only to oral form of both agents. Modify Therapy/Monitor Closely. Velpatasvir solubility decreases as gastric pH increases (practically insoluble at pH >5). Separate administration of sofosbuvir/velpatasvir from antacids by at least 4 hr.

              • vismodegib

                magnesium oxide will decrease the level or effect of vismodegib by Other (see comment). Use Caution/Monitor. Drugs that increase gastric pH alter vismodegib solubility and therefore reduce bioavailability; effect on efficacy unknown

              Minor (40)

              • amikacin

                amikacin decreases levels of magnesium oxide by increasing renal clearance. Minor/Significance Unknown.

              • amiloride

                amiloride increases levels of magnesium oxide by decreasing renal clearance. Minor/Significance Unknown.

              • amphotericin B deoxycholate

                amphotericin B deoxycholate decreases levels of magnesium oxide by increasing renal clearance. Minor/Significance Unknown.

              • bazedoxifene/conjugated estrogens

                bazedoxifene/conjugated estrogens decreases levels of magnesium oxide by Other (see comment). Minor/Significance Unknown. Comment: Magnesium shifted from blood to tissue storage.

              • bendroflumethiazide

                bendroflumethiazide decreases levels of magnesium oxide by increasing renal clearance. Minor/Significance Unknown.

              • bumetanide

                bumetanide decreases levels of magnesium oxide by increasing renal clearance. Minor/Significance Unknown.

              • calcitonin salmon

                calcitonin salmon increases levels of magnesium oxide by decreasing renal clearance. Minor/Significance Unknown.

              • chlorothiazide

                chlorothiazide decreases levels of magnesium oxide by increasing renal clearance. Minor/Significance Unknown.

              • chlorthalidone

                chlorthalidone decreases levels of magnesium oxide by increasing renal clearance. Minor/Significance Unknown.

              • cisplatin

                cisplatin decreases levels of magnesium oxide by increasing renal clearance. Minor/Significance Unknown.

              • conjugated estrogens

                conjugated estrogens decreases levels of magnesium oxide by Other (see comment). Minor/Significance Unknown. Comment: Magnesium shifted from blood to tissue storage.

              • conjugated estrogens, vaginal

                conjugated estrogens, vaginal decreases levels of magnesium oxide by Other (see comment). Minor/Significance Unknown. Comment: Magnesium shifted from blood to tissue storage.

              • cyclopenthiazide

                cyclopenthiazide decreases levels of magnesium oxide by increasing renal clearance. Minor/Significance Unknown.

              • dextrose

                dextrose decreases levels of magnesium oxide by increasing renal clearance. Minor/Significance Unknown.

              • digoxin

                digoxin decreases levels of magnesium oxide by increasing renal clearance. Minor/Significance Unknown.

              • doxercalciferol

                doxercalciferol increases levels of magnesium oxide by enhancing GI absorption. Applies only to oral form of both agents. Minor/Significance Unknown.

              • drospirenone

                drospirenone increases levels of magnesium oxide by decreasing renal clearance. Minor/Significance Unknown.

              • estradiol

                estradiol decreases levels of magnesium oxide by Other (see comment). Minor/Significance Unknown. Comment: Magnesium shifted from blood to tissue storage.

              • estrogens conjugated synthetic

                estrogens conjugated synthetic decreases levels of magnesium oxide by Other (see comment). Minor/Significance Unknown. Comment: Magnesium shifted from blood to tissue storage.

              • estrogens esterified

                estrogens esterified decreases levels of magnesium oxide by Other (see comment). Minor/Significance Unknown. Comment: Magnesium shifted from blood to tissue storage.

              • estropipate

                estropipate decreases levels of magnesium oxide by Other (see comment). Minor/Significance Unknown. Comment: Magnesium shifted from blood to tissue storage.

              • ethacrynic acid

                ethacrynic acid decreases levels of magnesium oxide by increasing renal clearance. Minor/Significance Unknown.

              • furosemide

                furosemide decreases levels of magnesium oxide by increasing renal clearance. Minor/Significance Unknown.

              • gentamicin

                gentamicin decreases levels of magnesium oxide by increasing renal clearance. Minor/Significance Unknown.

              • glucagon intranasal

                glucagon intranasal increases levels of magnesium oxide by decreasing renal clearance. Minor/Significance Unknown.

              • hydrochlorothiazide

                hydrochlorothiazide decreases levels of magnesium oxide by increasing renal clearance. Minor/Significance Unknown.

              • ibandronate

                magnesium oxide decreases levels of ibandronate by inhibition of GI absorption. Applies only to oral form of both agents. Minor/Significance Unknown.

              • indapamide

                indapamide decreases levels of magnesium oxide by increasing renal clearance. Minor/Significance Unknown.

              • mannitol

                mannitol decreases levels of magnesium oxide by increasing renal clearance. Minor/Significance Unknown.

              • mestranol

                mestranol decreases levels of magnesium oxide by Other (see comment). Minor/Significance Unknown. Comment: Magnesium shifted from blood to tissue storage.

              • metolazone

                metolazone decreases levels of magnesium oxide by increasing renal clearance. Minor/Significance Unknown.

              • neomycin PO

                neomycin PO decreases levels of magnesium oxide by increasing renal clearance. Minor/Significance Unknown.

              • nitrofurantoin

                magnesium oxide decreases levels of nitrofurantoin by inhibition of GI absorption. Applies only to oral form of both agents. Minor/Significance Unknown.

              • paromomycin

                paromomycin decreases levels of magnesium oxide by increasing renal clearance. Minor/Significance Unknown.

              • sodium polystyrene sulfonate

                sodium polystyrene sulfonate increases levels of magnesium oxide by decreasing renal clearance. Minor/Significance Unknown. Risk of alkalosis.

              • spironolactone

                spironolactone increases levels of magnesium oxide by decreasing renal clearance. Minor/Significance Unknown.

              • streptomycin

                streptomycin decreases levels of magnesium oxide by increasing renal clearance. Minor/Significance Unknown.

              • tobramycin

                tobramycin decreases levels of magnesium oxide by increasing renal clearance. Minor/Significance Unknown.

              • torsemide

                torsemide decreases levels of magnesium oxide by increasing renal clearance. Minor/Significance Unknown.

              • triamterene

                triamterene increases levels of magnesium oxide by decreasing renal clearance. Minor/Significance Unknown.

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              Adverse Effects

              Frequency Not Defined

              Diarrhea with excessive dose

              Gastrointestinal irritation

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              Warnings

              Contraindications

              Hypersensitivity

              Cautions

              Normal serum magnesium ~1.5-2.5 mg/dL

              Laxative effect

              Magnesium supplementation may exacerbate

              Caution with renal impairment

              Caution with myasthenia gravis or other neuromuscular diseases

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              Pregnancy & Lactation

              Pregnancy Category: A; 350-400 mg/day elemental Mg recommended during pregnancy

              Lactation: Distributed in breast milk; 310-360 mg/day elemental Mg recommended during lactation

              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

              Mineral; cofactor in many enzymatic reactions and essential for various metabolic functions (eg, phosphate transfer, muscle contraction, nerve conduction)

              Pharmacokinetics

              Absorption: Inversely proportional to dose; ~50% with controlled dietary intake, compared with 15-30% with high dose

              Distribution sites: 50-60% (bone); 1-2% (extracellular fluid)

              Protein Bound: 30% (albumin)

              Excretion: Urine

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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.