Indication

Convulsions of eclampsia, pre-eclampsia

Adult Dose

Eclampsia\r\nSevere pre-eclampsia or eclampsia\r\nThe total initial dose is 10 to 14 g of magnesium sulfate. \r\nTo initiate therapy, 4 g of Magnesium Sulfate in 5% Dextrose Injection, may be administered intravenously. \r\nThe rate of I.V. infusion should generally not exceed 150 mg/minute, or 7.5 mL of a 2% concentration (or its equivalent) per minute, except in severe eclampsia with seizures. \r\n\r\nSimultaneously, 4 to 5 g (32.5 to 40.6 mEq) of magnesium sulfate may be administered intramuscularly into each buttock using undiluted 50% Magnesium Sulfate Injection. After the initial I.V. dose, some clinicians administer 1-2 g/hour by constant I.V. infusion.\r\n\r\nSubsequent intramuscular doses of 4 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.

Contraindication

Heart block, severe renal impairment, myocardial damage.

Mode of Action

Magnesium sulfate decreases levels of acetylcholine in motor nerve terminals. It also acts on the myocardium by decreasing the rate of SA node impulse formation and prolonging the conduction time.

Precaution

Renal impairment, myasthaenia gravis, digitalised patients; pregnancy. Monitor serum-magnesium concentrations.

Side Effect

Hypermagnesaemia characterised by nausea, vomiting, flushing, thirst, hypotension, drowsiness, confusion, slurred speech, double vision, bradycardia, muscle weakness. Hypocalcaemia; paralytic ileus.

Interaction

Enhances neuromuscular blockers, digitalis glycosides.