Yes

Antacid; Electrolyte Supplement, Oral; Laxative, Saline; Magnesium Salt

Short-term treatment of occasional constipation and symptoms of hyperacidity

B

Patients with colostomy or an ileostomy, appendicitis, ulcerative colitis, diverticulitis, heart block, myocardial damage, serious renal impairment, hepatitis, Addison's disease, hypersensitivity to any component

Hypermagnesemia and toxicity may occur due to decreased renal clearance (Cl_cr <30 mL/minute) of absorbed magnesium; monitor serum magnesium level, respiratory rate, deep tendon reflex, renal function when MgSO₄ is administered parenterally; use with caution in digitalized patients (may alter cardiac conduction leading heart block); use with caution in patients with lithium administration; elderly, due to disease or drug therapy, may be predisposed to diarrhea; diarrhea may result in electrolyte imbalance; monitor for toxicity

>10%: Gastrointestinal: Diarrhea

1% to 10%:

Cardiovascular: Hypotension, EKG changes

Central nervous system: Mental depression, coma

Gastrointestinal: Nausea, vomiting

Respiratory: Respiratory depression

Magnesium antacids are also laxative and may cause diarrhea and hypokalemia. In patients with renal failure, magnesium may accumulate to toxic levels.

I.V. calcium (5-10 mEq) will reverse respiratory depression or heart block; in extreme cases, peritoneal dialysis or hemodialysis may be required.

Decreased effect: Tetracyclines, digoxin, indomethacin, iron salts, isoniazid, quinolones

Promotes bowel evacuation by causing osmotic retention of fluid which distends the colon with increased peristaltic activity

Onset of laxative action: 4-8 hours

Elimination: Absorbed magnesium ions (up to 30%) are usually excreted by kidneys, unabsorbed drug is excreted in feces

Adults: Oral:

Antacid: 140 mg 3-4 times/day or 400-840 mg/day

Laxative: 2-4 g at bedtime with full glass of water

Dosing in renal impairment: Patients in severe renal failure should not receive magnesium due to toxicity from accumulation. Patients with a Cl_cr <25 mL/minute should be monitored by serum magnesium levels.

Note: Oral magnesium is not generally adequate for repletion in patients with serum magnesium concentrations <1.5 mEq/L

Should be administered after meals

Tablet may be chewed

Serum magnesium:

Adults: 1.5-2.5 mg/dL (1.2-2.0 mEq/L)

magnesium; protein, calcium (S), potassium (S)

May rarely cause depression

None reported

No information available to require special precautions

Magnesium products may prevent gastrointestinal absorption of tetracyclines by forming a large ionized chelated molecule with the tetracyclines in the stomach. Tetracyclines should be given at least 1 hour before magnesium.

Chew tablets before swallowing; take with full glass of water; notify physician if relief not obtained or if any signs of bleeding occur (black tarry stools, "coffee ground" vomit)

Monitor for diarrhea and signs of hypermagnesemia

Capsule: 140 mg

Tablet: 400 mg, 425 mg

Chernow B, Smith J, Rainey TG, et al, "Hypomagnesemia: Implications for the Critical Care Specialist," Crit Care Med, 1982, 10(3):193-6.

Gams JG, "Clinical Significance of Magnesium: A Review," Drug Intell Clin Pharm, 1987, 21(3):240-6.