Nicardipine does not significantly affect serum digoxin concentrations at the steady state of patients with congestive heart failure.

Twenty patients in a stable condition suffering from congestive heart failure were treated with digoxin for at least three weeks and then with nicardipine concomitantly for five days. No statistically significant variation in serum digoxin concentrations determined at seven control times during a 24-hour period or in its mean concentration was found in the two groups of values examined before and after the concurrent nicardipine treatment. The mean increase of 6.8% in the AUC 0→24h was not significant either. Since the maximum increase in serum digoxin concentrations at the steady state never exceeded 0.5 ng/ml, a toxic effect is not likely to occur in patients whose digoxin levels are normally monitored.