Electrocardiographic effect of quinine and quinidine in the treatment of falciparum malaria

Quinidine has been suggested as an acceptable alternative to quinidine in the treatment of falciparummalaria. To compare the electrocardiographic effects of quinine and quinidine in falcaparum malaria, sixty patients with more than 2 per cent of parasitized red cells were chosenand paired as closely as possible. The study was double-blind. 15 mg/kg quinine or quinidine was given as a loading dose infused over 4 hours followed by 2 doses of 7.5 mg/kg base at 8 hourly intervals. Oral quinine or quinidine as 7.5 mg/kg base 3 times/day was then continued till day 7. Satisifactory 12 lead electrocardiograms were obtained from 58 patients on day 0, after 24 hours, on day 3 and on day 7. Overall there was no significant change in PR interval or ORS duration. The pretreatment QTc was 443+ or -30 msec in the quinine group (n=30) and 438+ or -25 msec in the quinidine group (n=28) with no significant difference. MAximum QTc prolongation occured on the third day in both groups being 481+ or -28msec in the quinine group and this was significantly less than 532+ or -55 msec seen in the quinidine group. QTc > 550 msec was found in 46.6 per cent in the quinidine group but in only one in the quinine group.T wave flattening occurred in 62 per cent in the quinidine group but in only 25 per cent in the quinine group. No dysrhythmias were recorded in this study but because of the excessive prolongation of the Qtc caused by quinidine, we conclude that we should be cautious about the use of quinidine for falciparum malaria.