Methyl 5(6)-(alpha-hydroxyphenyl methyl) benzimidazole-2-carbamate and cysticercosis: chemotherapeutic and electron microscopic studies.

: Methyl 5(6)-(alpha-hydroxyphenyl methyl) benzimidazole-2-carbamate, a major metabolite of mebendazole was evaluated against Cysticercus fasciolaria (larval form of Taenia taeniaeformis) in rats. The metabolite was assessed in various doses. A regimen of 50 mg/kg x 10 (ip), given one day apart, was found to be most effective and killed all the mature cysticerci. On developing cysts, the treatment was initiated in two schedules; 5 days prior to (d-5 to d-1) and 5 days after (d + 6 to d + 10) administration of T. taeniaeformis eggs to rats. The later protocol with 100 mg/kg x 5 dose (ip) resulted in 95% inhibition in the establishment of cysticerci. Activity of mebendazole against mature cysts was parallel to metabolite whereas against developing cysts, it was inferior. The time related topographical changes that occurred in mature C. fasciolaris after treatment with metabolite (50 mg/kg x 10, ip, one day apart) were observed by scanning electron microscopy. There was loss of contractivity, gradual disappearance of microtriches and progressive degeneration of tegument. Similar changes were noticed with mebendazole. The possession of better efficacy and higher safety range [Indian J Exp. Biol, 25 (1987) 871], suggests that the metabolite can be a potential anthelmintic for man and animals.