Electrocardiographic changes induced by levamisole hydrochloride in the guinea-pig

The effects of various i.v. doses of levamisole on the ECG of the anaesthetized guinea-pigs were determined. At 6 mg/kg there were no changes in the heart rate, P-R and Q-T intervals and no cardiotoxic effects were observed. At 10 and 20 mg/kg these parameters were affected little but cardiotoxic effects, mainly ventricular extrasystoles lasting from a few seconds to several minutes, were observed in five out of 10 animals that received either of the two doses. No animal died during the 1 h period of observation. It would appear that levamisole is much less toxic to the guinea-pig heart than to the heart of the rat.