This document discusses anti-protozoal drugs used to treat amoebiasis. It describes three classes of intestinal amoebicides: tissue amoebicides that act in both the intestine and other tissues like emetine and metronidazole; those that only act in other tissues like chloroquine; and luminal amoebicides that act only in the intestine like diloxanide furate. It focuses on metronidazole, the prototype nitroimidazole drug, which has higher amoebicidal and anti-anaerobic activity. It explains that metronidazole is activated by anaerobic bacteria through nitro group reduction, inhibiting amoebic DNA