Absorption Rate Studies of Orally Administered Cardiac Glycosides in Cats^†

Abstract

Digitoxin, acetyl digoxin, digoxin, and lanatoside C were administered orally to unanesthetized cats in single fatal doses. Physical state of subdivision and lipoid solubility appeared to modify rate of absorption. Digitoxin, acetyl digoxin, and digoxin were rather uniformly and nearly completely absorbed within a few hours, provided they were dissolved in aqueous alcohol or aqueous “Tween 80” solutions. Lanatoside C was slowly absorbed in alcoholic solution. Digoxin and lanatoside C tablets were absorbed very slowly. Lanatoside C is much less lipoid‐soluble than the others. It is postulated that high lipoid solubility of digitoxin and acetyl digoxin assures absorption of solid and dissolved states, whereas low lipoid solubility retards absorption of digoxin tablets and lanatoside C in solid or in solution. Acetyl digoxin deserves clinical trial as a substitute for digitoxin. Digoxin in alcohol or “Tween 80” solution should be as potent as digitoxin in solution.