Leucopenia and abnormal liver function in travellers on malaria chemoprophylaxis

Of 2887 travellers between the years 1984-1985, 451 on prophylactic antimalarials were studied retrospectively for adverse haematological or hepatic drug reactions and compared to 296 drug non-users. Travellers using amodiaquine, chloroquine, or pyrimethamine for less than 10 weeks had significantly lower total leucocyte counts than non-users. This was due to diminution of lymphocytes, not neutrophils. Travellers using amodiaquine for less than 10 weeks also had significantly higher serum aspartate aminotransferase (SGPT) levels than non-users. Amodiaquine was associated with a 3.1-times increased risk (95% confidence limits 1.8-5.4) of abnormal SGPT values. We consider toxic products, including metabolites of amodiaquine, the most likely cause of amodiaquine-related hepatotoxicity in travellers.