Assessment of bio(in)equivalence of deriphyllin-digoxin in human volunteers.

Bioavailability of digoxin from the formulations of a fixed dose combination of the glycoside with xanthines was compared with that of "Lanoxin". The in vitro analysis of the fixed dose "Deriphyllin-Digoxin" tablets showed that these tablets had low dissolution even at the end of four hours. The in vivo study had a randomized cross-over design with a 14 days wash-out period. The formulations were administered to 14 healthy adult volunteers and periodic blood samples were collected up to 24 hours. The samples were analyzed for digoxin concentration using radioimmunoassay. Results indicate poor and delayed absorption of digoxin from the fixed dose combination. It is concluded that a multiple dose study with pharmacodynamic assessment, in patients or in volunteers, would be adequate to critically reassess the need for the marketed fixed dose combination.