Magnesium Chloride

Correction or prevention of hypomagnesemia; dietary supplement

Hypersensitivity to any component of the formulation; renal impairment; myocardial disease; coma

Note: Serum magnesium is poor reflection of repletional status as the majority of magnesium is intracellular; serum levels may be transiently normal for a few hours after a dose is given; therefore, aim for consistently high normal serum levels in patients with normal renal function for most efficient repletion.

Dietary supplement: Oral (Mag 64, Mag-Delay, Slow-Mag): 2 tablets once daily

Hypomagnesemia, prevention (parenteral nutrition supplementation) (ASPEN [Mirtallo 2004]): IV (elemental magnesium): 8 to 20 mEq/day

RDA (elemental magnesium) (IOM 1997): Oral:

19 to 30 years:

Females: 310 mg/day

Pregnancy: 350 mg/day

Lactation: 310 mg/day

Males: 400 mg/day

≥31 years:

Females: 320 mg/day

Pregnancy: 360 mg/day

Lactation: 320 mg/day

Males: 420 mg/day

Refer to adult dosing.

No dosage adjustment provided in manufacturer’s labeling.

Whole grains, legumes, and dark-green leafy vegetables are dietary sources of magnesium.

Injection: Prior to reconstitution, store at controlled room temperature of 15°C to 30°C (59°F to 86°F).

Disease-related concerns:

• Neuromuscular disease: Use with extreme caution in patients with myasthenia gravis or other neuromuscular disease.

• Renal impairment: Use with caution in patients with renal impairment; accumulation of magnesium may lead to magnesium intoxication.

Special populations:

• Obstetrics: Vigilant monitoring and safe administration techniques (ISMP Medication Safety Alert, 2005) recommended to avoid potential for errors resulting in toxicity. Monitor patient and fetal status, and serum magnesium levels closely.

Dosage form specific issues:

• Aluminum: The parenteral product may contain aluminum; toxic aluminum concentrations may be seen with high doses, prolonged use, or renal dysfunction. Premature neonates are at higher risk due to immature renal function and aluminum intake from other parenteral sources. Parenteral aluminum exposure of >4 to 5 mcg/kg/day is associated with CNS and bone toxicity; tissue loading may occur at lower doses (Federal Register, 2002). See manufacturer’s labeling.

• Benzyl alcohol and derivatives: Some dosage forms may contain benzyl alcohol; large amounts of benzyl alcohol (≥99 mg/kg/day) have been associated with a potentially fatal toxicity (“gasping syndrome”) in neonates; the “gasping syndrome” consists of metabolic acidosis, respiratory distress, gasping respirations, CNS dysfunction (including convulsions, intracranial hemorrhage), hypotension, and cardiovascular collapse (AAP ["Inactive" 1997]; CDC, 1982); some data suggests that benzoate displaces bilirubin from protein binding sites (Ahlfors, 2001); avoid or use dosage forms containing benzyl alcohol with caution in neonates. See manufacturer’s labeling.

Other warnings/precautions:

• Electrolyte abnormalities: Concurrent hypokalemia or hypocalcemia can accompany a magnesium deficit. Hypomagnesemia is associated with hypokalemia and requires correction in order to normalize potassium.

• Parenteral administration: Monitor serum magnesium level, respiratory rate, blood pressure, deep tendon reflex, and renal function when administered parenterally, particularly with repeated dosing; magnesium toxicity can lead to fatal cardiovascular arrest and/or respiratory paralysis.

WARNING/CAUTION: Even though it may be rare, some people may have very bad and sometimes deadly side effects when taking a drug. Tell your doctor or get medical help right away if you have any of the following signs or symptoms that may be related to a very bad side effect:

• Signs of an allergic reaction, like rash; hives; itching; red, swollen, blistered, or peeling skin with or without fever; wheezing; tightness in the chest or throat; trouble breathing or talking; unusual hoarseness; or swelling of the mouth, face, lips, tongue, or throat.
• Very upset stomach or throwing up.
• Very loose stools (diarrhea).