PROSPECTIVE RANDOMIZED COMPARISON OF TOXICITY OF 2 PROPHYLACTIC REGIMENS OF COTRIMOXAZOLE IN LEUKEMIC CHILDREN

Cotrimoxazole is currently used for Pneumocystis carinii pneumonia prophylaxis in leukemic children. The former regimen of continuous administration was recently replaced by intermittent administration. The antifolic activity of cotrimoxazole could theoretically enhance that of methotrexate, also administered to leukemic children. We report on a prospective, randomized study to compare two different regimens-continuous vs. 3 days a week-of cotrimoxazole prophylaxis. The aim of the study was to evaluate the toxicity, assuming that both regimens are equally effective to prevent P. carinii pneumonia. Seventy-seven leukemic children were enrolled; 67 were evaluable, 35 from arm A (continuous), 32 from arm B (intermittent cotrimoxazole administration). The conclusion was that long-term maintenance chemotherapy with antimetabolites produced lower levels of folate but normal levels of vitamin B-12 in leukemic children. This pattern did not vary between the continuous and the 3-days-a-week administration of cotrimoxazole prophylaxis. Thus it seems hypothesizable that the antimetabolic activity of methotrexate alone exceeds that of cotrimoxazole.