Magnesium Sulfate In Water For

INDICATIONS AND USAGE Magnesium sulfate in water for injection is indicated for the prevention and control of seizures in preeclampsia and eclampsia, respectively. When used judiciously it effectively prevents and controls the convulsions of eclampsia without producing deleterious depression of the central nervous system of the mother or infant. However, other effective drugs are available for this purpose.

DOSAGE AND ADMINISTRATION Magnesium sulfate in water for injection is intended for intravenous use only. For the management of pre-eclampsia or eclampsia, intravenous infusions of dilute solutions of magnesium (1% to 8%) are often given in combination with intramuscular injections of 50% Magnesium Sulfate Injection, USP. Therefore, in the clinical conditions cited below, both forms of therapy are noted, as appropriate. Continuous maternal administration of magnesium sulfate in pregnancy beyond 5 to 7 days can cause fetal abnormalities. In Eclampsia In severe pre-eclampsia or eclampsia, the total initial dose is 10 g to 14 g of magnesium sulfate. To initiate therapy, 4 g of Magnesium sulfate in water for injection may be administered intravenously. The rate of intravenous infusion should generally not exceed 150 mg/minute, or 3.75 mL of a 4% concentration (or its equivalent) per minute, except in severe eclampsia with seizures. Simultaneously, 4 g to 5 g (32.5 mEq to 40.6 mEq) of magnesium sulfate may be administered intramuscularly into each buttock using undiluted 50% Magnesium Sulfate Injection, USP. After the initial intravenous dose, some clinicians administer 1 g/hour to 2 g/hour by constant intravenous infusion. Subsequent intramuscular doses of 4 g to 5 g of magnesium sulfate may be injected into alternate buttocks every four hours, depending on the continuing presence of the patellar reflex, adequate respiratory function, and absence of signs of magnesium toxicity. Therapy should continue until paroxysms cease. A serum magnesium level of 6 mg/100 mL is considered optimal for control of seizures. A total daily (24 hr) dose of 30 g to 40 g magnesium sulfate should not be exceeded. In the presence of severe renal insufficiency, frequent serum magnesium concentrations must be obtained and the maximum dosage of magnesium sulfate is 20 g per 48 hours. Parenteral drug products should be inspected visually for particulate matter and discoloration prior to administration, whenever solution and container permit. Do not administer unless solution is clear. Discard unused portion.

ADVERSE REACTIONS The adverse effects of parenterally administered magnesium usually are the result of magnesium intoxication. These include flushing, sweating, hypotension, depressed reflexes, flaccid paralysis, hypothermia, circulatory collapse, cardiac and central nervous system depression proceeding to respiratory paralysis. Hypocalcemia with signs of tetany secondary to magnesium sulfate therapy for eclampsia has been reported.

Pharmacokinetics: Absorption: Intravenously administered magnesium is immediately absorbed. Distribution: Approximately 1% to 2% of total body magnesium is located in the extracellular fluid space. Magnesium is 30% bound to albumin. Metabolism: Magnesium is not metabolized. Excretion: Magnesium is excreted solely by the kidney at a rate proportional to the serum concentration and glomerular filtration. Special Populations: Renal Insufficiency: Magnesium is excreted solely by the kidney. In patients with severe renal insufficiency, the dose should be lower and frequent serum magnesium levels must be obtained (see DOSAGE AND ADMINISTRATION ). Hepatic Insufficiency: Magnesium is excreted solely by the kidney. No dosing adjustments are necessary in hepatic insufficiency. Drug-Drug Interactions: Drug induced renal losses of magnesium occur with the following drugs or drug classes: Aminoglycosides Cyclosporine Digitalis Alcohol Amphotericin B Diuretics Cisplatin