[Absolute bioavailability of beta-acetyldigoxin from tablets and drops in healthy subjects]

In a crossover design in random order 12 healthy male volunteers were given either beta-acetyldigoxin (Novodigal, CAS 5511-98-8) tablets, oral solution or i.v. application at a digoxin equivalent dose of 0.284 mg. To reach steady state each preparation was given for 10 days on a once-daily schedule. On days 8, 9 and 10 of each observation period blood was sampled to determine trough concentrations of digoxin in steady state. In addition, on day 10 blood was collected repeatedly at appropriate time intervals and urine was sampled concomitantly for 24 h. Trough values during steady state and 24 h AUC were used to calculate digoxin bioavailability for tablets and oral solution. From trough values, the mean bioavailability for beta-acetyldigoxin tablets was 91.2% (range 73.1-118.1) and for solution 93.8% (range 65.7-114.8). Using the AUCs 0-24 h at steady state bioavailability was calculated 77.7% for the tablets and 84.5% for the solution. Since trough values in steady state represent the body burden of digoxin which is supposed responsible for the therapeutic effect, trough values should be given priority for the determination of digoxin bioavailability from beta-acetyldigoxin tablets and solution. All formulations were well tolerated. No clinically relevant side effects were observed.