The effects of drugs on Onchocerca volvulus. 3. Trials of suramin at different dosages and a comparison of the brands Antrypol, Moranyl and Naganol.

Suramin and Mel W are the only two drugs at present known to be effective against the adult worms of Onchocerca volvulus, but in view of the unpredictable occurrence of fatal arsenical encephalopathy in a small proportion of patients receiving Mel W, suramin remains the preferred macrofilaricide in the treatment of onchocerciasis. It is therefore important to determine the suramin dosage schedules that will produce parasitological cures with minimal concomitant risks of toxic reactions. The criteria by which cures should be judged must also be appreciated.Courses of different duration and employing doses of 1.0 g, 0.5 g and 0.25 g suramin have been investigated for their action on adult worms and microfilariae, for the toxic reactions which they produce on the kidney, and for the level of suramin reached in the serum during treatment. A course of 5 or 6 weekly doses of 1.0 g has been shown to be the optimum for adults.It is sometimes stated without good foundation that different brands of suramin differ in their purity and chemical composition, thus producing inconsistent effects on the parasites and grave risks of toxic manifestations. The three main brands in current use in Africa (Antrypol, Moranyl and Naganol) have therefore been compared in a group of patients, using the same optimum dosage schedule for each preparation and recording the action of the various brands on the parasites, as well as their comparative toxicities and the serum suramin levels achieved. No significant differences between the brands were recorded.