Dosing and uses of Mag-Ox 400, Uro-Mag (magnesium oxide)
Adult dosage forms and 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
Pediatric dosage forms and 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
Mag-Ox 400, Uro-Mag (magnesium oxide) adverse (side) effects
Frequency not defined
Diarrhea with excessive dose
Gastrointestinal irritation
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
Pregnancy and 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.
Pharmacology of Mag-Ox 400, Uro-Mag (magnesium oxide)
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
