Experimental chemotherapy and toxicity in mice of three mebendazole polymorphic forms

In an attempt to test the biological activity of three polymorphic forms of mebendazole (MBZ), called A, B and C, both the LD50 in mice after oral (p.o.) and intraperitoneal (i.p.) administration and the anthelmintic effect of these forms on the enteral and parenteral phases of the nematode Trichinella spiralis were studied. We observed that the polymorphic form A was the least toxic and effective against T. spiralis. The use of the polymorph C is advisable for oral treatment with MBZ in mice, having in mind its lower toxicity with regard to the polymorphic form B and its similar anthelmintic effects.