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Obstetrics & Gynecology: July 1993
Original Article: PDF Only

Objective: To determine whether nicardipine, a dihydropyridine, inhibits the ability of calcium gluconate to reverse magnesium-induced toxicity.

Methods: The reversal of magnesium-induced neuromuscular blockade of skeletal muscle in the presence of nicardipine was assessed using a nerve stimulator. Nicardipine (12 mg) or an equivalent volume of saline was administered intramuscularly to 19 nonpregnant rabbits in a randomized, blinded manner. Magnesium sulfate, 800 mg, was then infused intravenously in all animals, an amount sufficient to cause toxicity as measured by depression of skeletal muscle twitch and by average serum levels of 10.4 mEq/L. Calcium gluconate (300 mg) was then infused in all animals, and reversal of neuromuscular blockade was measured using the nerve stimulator to compare the saline- and nicardipinetreated groups.

Results: Administration of calcium gluconate was equally effective in reversing magnesium-induced toxicity in both the control and test groups.

Conclusion: Nicardipine does not block the ability of calcium gluconate to reverse magnesium-induced neuromuscular blockade.

© 1993 The American College of Obstetricians and Gynecologists