Comparative efficacy of some benzimidazoles and amoscanate (Go.9333) against experimental filarial infections.

The comparative efficacy of mebendazole, fenbendazole, oxibendazole, oxfendazole, albendazole, flubendazole and micronized amoscanate (particle size 5-8 micron) against Litomosoides carinii and Brugia pahangi infections in Mastomys natalensis was studied on administration of the compounds per os (150 mg/kg/day for 5 days) and subcutaneous (100 mg/kg/day for 5 days) routes. It was found that benzimidazoles when given by the oral route had no effect on adults of L. carinii and B. pahangi. With most of these compounds there was a rise in microfilariae before registering a fall to varying degrees in the peripheral circulation. There was a gradual but effective reduction of microfilariae of L. carinii in animals treated orally with mebendazole (99%), flubendazole (95%) and oxfendazole (85%). No such effect was seen against B. pahangi microfilariae. On subcutaneous administration, all the benzimidazoles with the exception of fenbendazole exhibited marked macrofilaricidal activity against L. carinii. Such activity was not seen with oxibendazole, oxfendazole and fenbendazole against adults of B. pahangi. Amoscanate exhibited superiority over the benzimidazoles in that the compound eliminated microfilariae and adult worms of both L. carinii and B. pahangi species when given by oral and subcutaneous routes.