Responsiveness of chloroquine-induced pruritus to antihistamine therapy--a clinical survey.

A clinical survey in Benin (Nigeria) has revealed that 393 out of 541 respondents experienced pruritus (itching) whenever they took chloroquine for malaria treatment. The reaction was always severe in 90% of the cases. Based on this experience, the pruritus-prone subjects were subsequently given antihistamine therapy either 30 min before or along with chloroquine administration (initial dose, 600 mg base oral, or 200 mg base i.m.). The success rates obtained with the following antihistamines were 49% (chlorpheniramine maleate, 4-8 mg oral), 46% (mepyramine maleate, 50-100 mg oral), and 60% (Promethazine hydrochloride, 50 mg oral or i.m.). Promethazine appears to be the most effective in the prevention of chloroquine-induced pruritus but the differences were not significant. The antihistamine was more frequently given 30 min before chloroquine, but this had no advantage over the concomitant administration of the two drugs, which may therefore be presented in one dosage form for a better treatment compliance.