This document discusses different classes of antihelmintic drugs used to treat parasite infections caused by flatworms and roundworms. It outlines 9 main classes: benzimidazoles, quinoline and isoquinolines, piperazine derivatives, vinylpyrimidines, amides, natural products, organophosphorus, imidazothiazoles, and nitro derivatives. Specific drugs discussed within each class include albendazole, oxibendazole, flubendazole, praziquantel, oxamniquine, and levamisole hydrochloride.