[Anti-arrhythmia properties of marcaine]

Comparative study of antiarrhythmic properties of marcaine and lidocaine was made on aconitine- and strophanthine-induced experimental arrhythmias and in rhythm disorders induced by electrical stimulation of the ventricles. Marcaine (5 mg/kg) prevented the development of rhythm disorders induced in rats by intravenous injection of aconitine (40 micrograms/kg) and also raised the arrhythmogenic dose of strophanthine (ouabain) in guinea-pigs. Administration of marcaine to anesthetized cats in a dose of 2 mg/kg reduced the assimilation of the rhythm imposed on the heart ventricles at the expense of an increase in the effective refractory period and increased the threshold of electrical fibrillation of the ventricles more noticeably and for a longer time as compared with lidocaine administered in a dose of 5 mg/kg. Marcaine compares very favourably with lidocaine as regards the potency and duration of the antiarrhythmic effect. However, it is inferior to lidocaine from the standpoint of the therapeutic action range. Toxic effects of marcaine do not make clear the prospects of its clinical use as an antiarrhythmic drug. Nevertheless the search of new effective antiarrhythmic drugs among marcaine analogs holds promise.