Digoxin-diltiazem interaction: a pharmacokinetic evaluation.

The pharmacokinetics of digoxin were studied before and after a 2 week course of diltiazem, 30 mg four times daily, in 7 healthy volunteers. Each subject received an IV dose of digoxin before starting diltiazem and again on day 15 of the study. Diltiazem was continued until all sera and urine were collected. During the control and diltiazem phases, respectively, the terminal elimination rate constants were 0.0231 +/- 0.007 h-1 and 0.0254 +/- 0.007 h-1, the volumes of distribution were 10.5 +/- 3.95 l/kg and 10.2 +/- 3.26 l/kg, and the total body clearances were 3.72 +/- 0.78 ml X min-1 X kg-1 and 4.09 +/- 0.94 ml X min-1 X kg-1. None of these pharmacokinetic parameters of digoxin were significantly different before or during diltiazem administration. Overall, there does not appear to be an interaction between digoxin and diltiazem.