INTESTINAL ABSORPTION OF CARDIAC GLYCOSIDES IN VITRO AND IN VIVO

1. Penetration and binding of tritiated ouabain, digitoxin, digoxin, peruvosid and proscillaridin were studied on isolated segments of the small intestine of rats and guinea pigs in vitro. 2. Penetration of glycosides through the intestinal wall is proportional to concentration. In rat intestine the penetration rate follows the order: digitoxin, peruvosid, proscillaridin = digoxin, ouabain; in guinea pig intestine: proscillaridin peruvosid = digitoxin, ouabain, digoxin. 3. In intestinal tissue of rats as well as of guinea pigs binding of digitoxin is highest. The relation of the glycoside content per g intestine to the content per ml perfusion fluid in the rat is 3.3 for digitoxin, 0.18 for ouabain, 0.6 for digoxin, 1.1 for peruvosid and 1.2 for proscillaridin; in the guinea pig 4.2 for digitoxin, 0.8 for ouabain, 0.16 for digoxin, 0.9 for peruvosid and 1.4 for proscillaridin. 4. Also in vivo the absorption of glycosides in tied loops of rat intestine is proportional to the amount offered. The retention of glycosides depends mainly on the excretion via the bile. 5. There is no indication that the absorption of glycosides depends on a process of limited capacity. © 1969 Springer-Verlag.