Tissue Distribution of Cardiac Glycosides

Abstract

The treatment of cardiac failure is complicated by the difficulty in determining the optimal therapeutic response and undesirable side-effects. The side-effects of cardiac glycosides can be categorized into two generai classes, those of a neurologic nature including fatigue, loss of appetite, vomiting, color vision, central scotoma, states of confusion and delirium, and those of a cardiac nature, primarily those of alterations in cardiac rate and rhythm (Schwiegk and Jahrmärker, 1960; Lely and van Enter, 1972). Both organ-specific side-effects can occur with varying duration and either simultaneously or independently of each other (Fowler et al, 1964; Bloch, 1964; Lely and van Enter, 1970). The existing dissociation between the duration of cardiac and central effects has been shown in a case study of digitalis delirium by Church and Marriott (1959). This study is of particular interest, since the psychotic state outlasted the cardiac side-effects of digoxin intoxication. Four days af ter digoxin administration was stopped, a normalization of heart rate and sinus rhythm without extrasystoles in the ECG was observed. In contrast, the central side-effects such as anorexia, dizziness, blurring of vision, and the Symptoms of a typical digitalis delirium lasted longer than 2 weeks. The different duration of the cardiac and central effects of digitalis preparations may be caused by different élimination rates of both tissue compartments. This could be confirmed by the following studies in dog and man.