Kinetics of digitoxin and the bis- and monodigitoxosides of digitoxigenin in normal subjects.

The kinetics of digitoxin and two of its metabolites, the bis- and monodigitoxosides of digitoxigenin, were determined in six normal subjects. Mean t 1/2s and total body clearances were 134.4, 15.4, and 0.59 hr and 2.66, 27.3, and 1071 ml/min. Mean renal clearance of the monodigitoxoside was more rapid (7.24 ml/min) than those of digitoxin (0.81 ml/min) or the bisdigitoxoside (0.94 ml/min). The volumes of distribution were of the same order, 0.45 l/kg for digitoxin, 0.57 l/kg for the bisdigitoxoside, and 0.83 l/kg for the monodigitoxoside. The short t 1/2 of monodigitoxoside would make it unsuitable for clinical use, but the bisdigitoxoside of digitoxigenin has a t 1/2 of an intermediate length and may have significant therapeutic advantages.