The comparative bioavailability of Lanoxin tablets and Lanoxicaps with and without sorbitol

Abstract
(1) The mean cumulative urinary digoxin excretion over 8 days was compared in 8 healthy volunteers after single doses of digoxin administered as 3 Lanoxin tablets of 0.25 mg, 3 digoxin tablets of 0.2 mg, 12 Lanoxicaps without sorbitol of 0.05 mg, 6 Lanoxicaps without sorbitol of 0.1 mg digoxin, 3 Lanoxicaps without sorbitol of 0.2 mg and 3 Lanoxicaps with sorbitol of 0.2 mg. (2) There was no significant difference between the 8 day cumulative urinary excretion for any of the Lanoxicaps treatments. (3) Cumulative urinary excretion after 3 digoxin tablets of 0.2 mg was significantly (P<0.05) lower than after all other treatments. (4) Cumulative urinary excretion after 3 Lanoxin tablets of 0.25 mg was not significantly different from that after any of the Lanoxicaps treatments except 0.1 mg Lanoxicaps without sorbitol, it was significantly (P<0.05) lower after the latter. (5) Mean urinary excretion of digoxin was 60% of ingested dose for all Lanoxicaps treatments and was significantly (P<0.05) higher than the mean value of 50% for both tablet treatments. (6) Enhanced absorption of digoxin from Lanoxicaps was confirmed and shown to be unrelated to the sorbitol content of the capsule shell.