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MAGNESIUM OXIDE

Medical Diagnosis and Drugs, Medications
MAGNESIUM OXIDE
(mag-nes'i-um)
Mag-Ox, Maox, Par-Mag, Uro-Mag
Classifications: antacid; saline cathartic;
Therapeutic: antacid; magnesium supplement; laxative
Prototype: Magnesium hydroxide
Pregnancy Category: A

Availability

400 mg, 420 mg, 500 mg tablets; 140 mg capsules

Action

Nonsystemic antacid with high neutralizing capacity and relatively long duration of action.

Therapeutic Effect

Acts as an antacid in low doses and a mild saline laxative at higher doses. Also effective as a magnesium supplement.

Uses

Essentially the same as magnesium hydroxide. May also be used as magnesium supplement.

Contraindications

Abdominal pain, nausea, vomiting, diarrhea, severe kidney dysfunction, fecal impaction, intestinal obstruction or perforation, ileus; rectal bleeding, colostomy, ileostomy; AV block; hypermagnesia; children <2 y.

Cautious Use

Cardiac disease, renal disease, renal impairment; electrolyte imbalance; pregnancy (category A), lactation.

Route & Dosage

Antacid
Adult: PO 280–1500 mg with water or milk q.i.d., p.c. and h.s.

Laxative
Adult: PO 2–4 g with water or milk h.s.

Magnesium Supplement
Adult: PO 400–1200 mg/d in divided doses

Administration

Oral
  • Separate administration of this drug from other oral drugs by 1–2 h.
  • Store at 15°–30° C (59°–86° F) in airtight containers. On exposure to air, magnesium oxide rapidly absorbs moisture and carbon dioxide.

Adverse Effects (≥1%)

GI: Diarrhea, abdominal cramps, nausea; hypermagnesemia, kidney stones (chronic use).

Interactions

Drug: See magnesium hydroxide.

Pharmacokinetics

Absorption: 30–50% from GI tract. Elimination: In urine.

Nursing Implications

Assessment & Drug Effects

  • Monitor for dehydration, hypokalemia, and hyponatremia (see Appendix F) since drug may cause intense bowel evacuation.
  • Lab tests: Check patients on prolonged therapy periodically for electrolyte imbalance (i.e., hypermagnesemia).

Patient & Family Education

  • Liquid preparation is reportedly more effective than the tablet form, as with other antacids.

Common adverse effects in italic, life-threatening effects underlined; generic names in bold; classifications in SMALL CAPS; Canadian drug name; Prototype drug

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