The effects of some drugs--pentamidine, stibocaptate, Hoechst 33258, F 151, compound 'E' and Nifurtimox--on Onchocerca volvulus in chimpanzees.

Several drugs were investigated for action against Onchocerca volvulus in chimpanzees. Pentamidine at 4 mg/kg daily for 16 days had no filaricidal action; nor did stibocaptate at 10 mg/kg monthly for 8 months. Hoechst 33258, a substituted bis-benzamidazole, showed micro- and macrofilaricidal activity; F151 (an arsenical compound) showed a purely macrofilaricidal action; and Compound E (a reaction product of Hoechst 33258 and F151) was micro- and macrofilaricidal. The toxicity of the three last-mentioned compounds was high, and further trials were not made. Nifurtimox, at doses of up to 40 mg/kg for 10 days, was shown not be microfilaricidal, but there was a suggestion that this drug may have some macrofilaricidal action.