Carvedilol increases the systemic bioavailability of oral digoxin.

The effects of a single oral dose of 25 mg carvedilol on the plasma and urinary kinetics of digoxin after an oral and intravenous 0.5 mg dose, were investigated in two separate double-blind, placebo-controlled, period-balanced cross-over studies in healthy male subjects. Carvedilol increased the mean maximum plasma concentration and the area under the plasma concentration time-curve of digoxin when administered orally. The effects were virtually confined to the first 4 h after dosing, and the apparent terminal disposition rate constant was not changed. Carvedilol did not alter the plasma and urinary kinetics of intravenously administered digoxin.