A Method for determining the Duration of Action of the Cardiac Glycosides

Abstract

THE determination of the duration of action of the cardiac glycosides has depended mainly on toxicity experiments which require large numbers of animals. The Hatcher method¹ depends on the difference between the usual lethal dose of a suitable cardiac glycoside and the actual dose required to kill at various times after the administration of the cardiac glycoside under test. Another method developed by Hauptstein² makes use of the relationship between the rate of infusion and the toxic dose of a cardiac glycoside ; the decrease in toxicity with slow rates of infusion indicates the degree of elimination (detoxification and excretion). Data on the duration of action are also available from clinical records, where the criterion for the persistence of cardiac activity after the administration of a cardiac glycoside can be electrocardiographic changes such as alteration of the T-wave or decrease in heart-rate, or the therapeutic effect, although this is difficult to evaluate precisely.