Antifilarials and their mode of action

Diethylcarbamazine and suramin are the drugs of choice for the control of lymphatic filariasis and onchocerciasis respectively. Benzimidazoles, ivermectin, furapyrimidone, and isothiocyanates and their derivatives emerge as compounds of potential clinical interest as antifilarials. Diethylcarbamazine is predominantly a microfilaricide affecting the neuromuscular system of the parasites and promotes cellular cytotoxicity mediated by immune factors. Suramin is macrofilaricidal, has a narrow therapeutic index and damages the intestinal epithelium of the worms. Benzimidazoles bind to tubulins and inhibit their assembly to microtubules. Ivermectin is an extremely potent microfilaricide in onchocerciasis; it augments immune responses and impairs the neuromuscular function of the parasites, leading to paralysis. Isothiocyanates and their derivatives are both microfilaricidal and macrofilaricidal and affect the energy metabolism of the parasites. Although the precise mode of action of antifilarial drugs is not established, information is available on the responses listed above and also on the effects of the drugs on the carbohydrate and folate metabolism of the parasites.