Albendazole versus ricobendazole (albendazole-sulphoxide) against enteral and parenteral stages of Trichinella spiralis in mice

Comparison of the anthelmintic activity and pharmacokinetic profiles following albendazole (ABZ) and albendazole-sulphodide (ricobendazole = RBZ) administration was made in a mouse model for helminthic infections. Swiss CD-1 mice were experimentally infected with Trichinella spiralis and treated with either ABZ or RBZ at 3 different stages of the parasite life-cycle: pre-adult (day 1 p.i.), migrating larvae (days 13, 14 and 15 p,i,) and encysted muscle larvae (days 34, 35 and 36 p,i,), Plasma concentrations of albendazole-sulphoxide (ABZSO) were measured in age matched non-infected mice by high performance liquid chromatography (HPLC), after administration of ABZ or RBZ dosed at 50 mg ABZ equivalent kg(-1). ABZSO pharmacokinetic profiles following ABZ or RBZ administration were similar, although the T-max (1.83 +/- 0.30 and 0.41 +/- 0.28, respectively) were significantly different (P < 0.01). Against pre-adult stages ABZ was significantly (P < 0.05) more effective than RBZ when administered at 10 mg kg(-1) (96.5% and 78.0% reduction with respect to the control group). Migrating and encysted larvae were less sensitive to both compounds and dose rates had to be increased to 100 mg kg(-1) to achieve significant efficacies. Against parenteral stages, ABZ was significantly more effective than RBZ when both were given at 100 mg kg(-1) (64.0% and 44.2% reduction against migrating larvae and 94.7% and 65.5% reduction against encysted larvae, respectively). In conclusion, RBZ was not more effective than ABZ against enteral and parenteral stages of Trichinella spiralis. (C) 1997 Australian Society for Parasitology. Published by Elsevier Science Ltd.