Chloroquine is an effective antimalarial and antiamoebic drug. It is most effective against all forms of Plasmodium vivax, Plasmodium malariae and Plasmodium ovale. The most resistant strains of Plasmodium falciparum. It is one of the most powerful and fast-acting schizontocides, as well as gametocides against Pl. vivax, Pl. ovale, Pl. malariae. It also acts on immature gametocytes of Plasmodium falciparum. Since the drug is ineffective against exoerythrocytic forms of malaria, it is not used for prophylaxis in cases of infection with Pl. vivax and Pl. ovale. The mechanism of its schizontocide action in the blood is not fully understood, but ultimately leads to disruption of the synthesis of the parasite's DNA. The mechanism of its action against trophozoite forms of Entamoeba hystolytica is similar to that of emetine. In addition to the above effects, the drug has anti-inflammatory and immunosuppressive effects, however, its toxicity limits the duration of therapy with this drug.