EFFECT OF NICARDIPINE ON THE REVERSAL OF MAGNESIUM TOXICITY BY CALCIUM GLUCONATE IN NONPREGNANT RABBITS

Objective: To determine whether nicardipine, a dihydropyridine, inhibi ts the ability of calcium gluconate to reverse magnesium-induced toxic ity. 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 sal ine was administered intramuscularly to 19 nonpregnant rabbits in a ra ndomized, blinded manner. Magnesium sulfate, 800 mg, was then infused intravenously in all animals, an amount sufficient to cause toxicity a s measured by depression of skeletal muscle twitch and by average seru m levels of 10.4 mEq/L. Calcium gluconate (300 mg) was then infused in all animals, and reversal of neuromuscular blockade was measured usin g the nerve stimulator to compare the saline- and nicardipine-treated groups.Results: Administration of calcium gluconate was equally effect ive in reversing magnesium-induced toxicity in both the control and te st groups. Conclusion: Nicardipine does not block the ability of calci um gluconate to reverse magnesium-induced neuromuscular blockade.