Bioavailability of the bis- and monodigitoxosides of digitoxigenin.

The pharmacokinetic behavior of digitoxigenin is affected by the number of glycosides present. This study was conducted to compare the bioavailabilities of the bis- and monodigitoxosides of digitoxigenin in man. Intravenous and oral doses of the two drugs were administered to six normal volunteers. Blood samples were collected up to 28 days after each dose, and assayed for the specific drug administered and for total radioassayable drug. Both drugs were virtually completely absorbed, based on serum concentrations of administered drug plus metabolites. However, the mean bioavailability of unchanged bisdigitoxoside was only 56.3% indicating that substantial metabolism occurred prior to entry into the systemic circulation. Monodigitoxoside was virtually completely metabolized prior to entry into the systemic circulation.