Efficacy of albendazole and mebendazole againstHymenolepis microstoma andHymenolepis diminuta

Abstract

An investigation of the chemotherapeutic effects of 2 anthelmintics, albendazole (ABZ, methyl 5-[propylthio]benzimidazole-2- carbamate) and mebendazole (MBZ, methyl 5-[benzoyl]benzimidazole-2-carbamate), on Hymenolepis microstoma and Hymenolepis diminuta in experimentally infected mice and rats is reported. Single (50 mg/kg) or multiple daily oral doses (50 mg kg-1 day-1 for 3 consecutive days) of MBZ had no effect on H. microstoma; at necropsy, the drug treated mice harbored appreciable numbers of the parasite in the bile duct and biliary passages. ABZ was also inactive when given as a single oral 50 mg/kg dose on day 27 PI. Better results were obtained when ABZ was administered at a dosage of 50 mg kg-1 day-1 for 3 consecutive days; the reduction in worm burden obtained with this treatment regimen was 50%. These results are in marked contrast to those obtained with the same anthelmintics against enteral H. diminuta in rats which succumbed at lower dosages. A review was made of the published reports on the pharmacokinetic behavior of these benzimidazole carbamate anthelmintics and a hypothesis for the inactivity of MBZ against H. microstoma is proposed.

The anthelmintic efficacy of natural plant cysteine proteinases againstHymenolepis microstoma in vivo

“…There are some notable parallels between the observations reported here and in previous studies with other anthelmintics, to which H. microstoma was also found to be resilient. For example, this species is far more resistant to benzimidazoles than the considerably more susceptible H. diminuta (McCracken et al , 1992). Even at the larval stage, H. microstoma was found to be resistant to benzimidazole-based preparations (Evans et al , 1979, 1980).…”

“…Since the relatively weak effect of PLS on H. microstoma may be attributable to its location, residing high in the bile duct where it is largely protected from contact with intestinal lumenal contents (de Rycke, 1966; McCracken et al , 1992), an experiment was carried out in which young and still migrating worms, fully exposed in the intestinal lumen, were subjected to CP treatment. Here we might have expected a marked reduction in all autopsy indices but, in actual fact, while significant, the actual percentage reductions compared with controls were again fairly minimal (fig.…”

“…Despite all the advantages, it is somewhat challenging and intriguing that with respect to anthelmintic susceptibility, H. microstoma has proven to be a resilient species, and therefore this model system provides a robust test of the efficacy of cestocidal drugs. From juvenile cysticercoids in the flour beetle intermediate host (Evans et al , 1979) to bile duct dwelling adult worms, all have shown resilience to benzimidazole-based preparations (McCracken et al , 1992) compared to the relatively more susceptible H. diminuta (Coles, 1983). Exact explanations remain elusive, but one possibility may be that a large portion of the worm is protected from direct contact with drugs passing down the lumen of the intestine, because of its location high up in the bile duct (McCracken et al , 1992).…”

The activity of drug-metabolizing enzymes and the biotransformation of selected anthelmintics in the model tapeworm Hymenolepis diminuta

“…Praziquantel and niclosamide represent drugs of choice for this helminthosis (Cohen and Mackey, 1977;Jones, 1979;Tanowitz et al 1993;Marangi et al 2003). The benzimidazole drugs (BZD), albendazole (ABZ), mebendazole (MBZ), flubendazole (FLU), thiabendazole and cambendazole are also effective in lessening tapeworm burden (McCracken and Taylor, 1983;Maki and Yanagisawa, 1985;McCracken et al 1992;Ostlind et al 2004).…”