Nifedipine enhances the cardiac toxicity of magnesium sulfate in the isolated perfused Sprague-Dawley rat heart.

Magnesium sulfate is commonly used in tocolytic regimens and as prophylaxis against seizures. Nifedipine may be used simultaneously in either situation. With the isolated perfused rat heart model (Sprague-Dawley rats), we investigated the effects of these agents on cardiac function. Whereas each agent alone depressed cardiac performance, the two drugs together had maximal depressive effects on the heart.