Greater bioavailability of digoxin solution in capsules. Studies in the postprandial state

A liquid concentrate of digoxin administered as a capsule has recently been found to be better absorbed by normal subjects in the fasting state than a standard tablet or even a solution as such. It was not known whether the enchanced bioavailability of the encapsulated digoxin solution could also be demonstrated when given postprandially. In a crossover study single 0.4 mg doses of digoxin solution in a capsule, a solution in 10% ethanol as such, and a standard tablet were given to 12 normal volunteers immediately following a high-fat breakfast. The mean area under the serum concentration-time curve (AUC) and 6-day cumulative urinary glycoside excretion (CUE) were greater after the capsule than that of either the solution or the tablet. The latter two preparations appeared to be bioequivalent. Intersubject variability in the CUE was less than with the AUC, but did not differ when the three drug formulations were compared. The bioavailability of an encapsulated liquid digoxin concentrate was thus also found to be enhanced when administered postprandially.