MAGNESIUM OXIDE
| 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