Some pharmacological studies on the cardiotonic effects of furanosteroidal glycosides

Cardiotonic effects and cardiotoxicities of three furanosteroidal glycosides were compared with those of standard cardiac glycosides (digitoxin, gitoxin, etc.). Furanosteroidal glycosides showed positive inotropic effects in both isolated guinea-pig atria and rabbit hearts. The positive inotropic effect of 17beta-(3-furyl)-5beta,14beta-androstane-3beta,14,16beta-triol-3-bisdigitoxoside(FGBD) corresponded to that of digitoxin in isolated guinea-pig atria and frog hearts. Intravenous and oral administration of FGBD and 17beta-(3-furyl)-5beta,14beta-androstane-3beta,14,16beta-triol-3-tridigitoxoside(FGTD) in higher doses induced cardiac arrest after vomiting, bradycardia, ventricular rhythm, and ventricular fibrillation in pigeons and cats. Comparison of lethal doses between intravenous and oral administration of cardiac glycosides in pigeons and cats suggested that gastrointestinal absorption of FGBD and FGTD is inferior to that of digitoxin but superior to that of gitoxigenin bisdigitoxoside and gitoxin. Cardiotonic effects of furanosteroidal glycosides were confirmed in isolated guinea-pig, rabbit and frog hearts.