Antiparasitic agents are medications used to treat infections caused by parasites, which are organisms that live on or in a host and benefit at the host's expense. These agents target various types of parasites, including protozoa, helminths (worms), and ectoparasites (like lice and ticks). They work by disrupting the life cycle of the parasites, ultimately leading to their elimination from the host. Common antiparasitic agents include metronidazole for protozoan infections, albendazole for helminth infections, and permethrin for ectoparasitic infestations. The choice of agent depends on the type of parasite and the specific infection being treated. Proper diagnosis and treatment are essential for effective management of parasitic diseases.