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Look Up > Drugs > Magnesium Hydroxide
Magnesium Hydroxide
Pronunciation
U.S. Brand Names
Generic Available
Synonyms
Pharmacological Index
Use
Pregnancy Risk Factor
Contraindications
Warnings/Precautions
Adverse Reactions
Overdosage/Toxicology
Drug Interactions
Mechanism of Action
Pharmacodynamics/Kinetics
Usual Dosage
Dietary Considerations
Reference Range
Test Interactions
Mental Health: Effects on Mental Status
Mental Health: Effects on Psychiatric Treatment
Dental Health: Local Anesthetic/Vasoconstrictor Precautions
Dental Health: Effects on Dental Treatment
Patient Information
Nursing Implications
Dosage Forms
References

Pronunciation
(mag NEE zhum hye DROKS ide)

U.S. Brand Names
Phillips'® Milk of Magnesia [OTC]

Generic Available

Yes


Synonyms
Magnesia Magma; Milk of Magnesia; MOM

Pharmacological Index

Antacid; Laxative, Saline; Magnesium Salt


Use

Short-term treatment of occasional constipation and symptoms of hyperacidity, magnesium replacement therapy


Pregnancy Risk Factor

B


Contraindications

Patients with colostomy or an ileostomy, intestinal obstruction, fecal impaction, renal failure, appendicitis, hypersensitivity to any component


Warnings/Precautions

Use with caution in patients with severe renal impairment, (especially when doses are >50 mEq magnesium/day); hypermagnesemia and toxicity may occur due to decreased renal clearance of absorbed magnesium. Decreased renal function (Clcr <30 mL/minute) may result in toxicity; monitor for toxicity.


Adverse Reactions

>10%: Gastrointestinal: Diarrhea

1% to 10%:

Cardiovascular: Hypotension

Endocrine & metabolic: Hypermagnesemia

Gastrointestinal: Abdominal cramps

Neuromuscular & skeletal: Muscle weakness

Respiratory: Respiratory depression


Overdosage/Toxicology

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.


Drug Interactions

Decreased effect: Decreased absorption of tetracyclines, digoxin, indomethacin, or iron salts


Mechanism of Action

Promotes bowel evacuation by causing osmotic retention of fluid which distends the colon with increased peristaltic activity; reacts with hydrochloric acid in stomach to form magnesium chloride


Pharmacodynamics/Kinetics

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


Usual Dosage

Oral:

Laxative:

<2 years: 0.5 mL/kg/dose

2-5 years: 5-15 mL/day or in divided doses

6-12 years: 15-30 mL/day or in divided doses

greater than or equal to 12 years: 30-60 mL/day or in divided doses

Antacid:

Children: 2.5-5 mL as needed up to 4 times/day

Adults: 5-15 mL up to 4 times/day as needed

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


Dietary Considerations

May be administered with fluids, taste can be improved by following each dose with citrus fruit juice


Reference Range

Serum magnesium:

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


Test Interactions

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


Mental Health: Effects on Mental Status

None reported


Mental Health: Effects on Psychiatric Treatment

None reported


Dental Health: Local Anesthetic/Vasoconstrictor Precautions

No information available to require special precautions


Dental Health: Effects on Dental Treatment

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.


Patient Information

Dilute dose in water or juice, shake well


Nursing Implications

MOM concentrate is 3 times as potent as regular strength product


Dosage Forms

Liquid: 390 mg/5 mL (10 mL, 15 mL, 20 mL, 30 mL, 100 mL, 120 mL, 180 mL, 360 mL, 720 mL)

Liquid, concentrate: 10 mL equivalent to 30 mL milk of magnesia USP

Suspension, oral: 2.5 g/30 mL (10 mL, 15 mL, 30 mL)

Tablet: 300 mg, 600 mg


References

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.


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