Reziz

Pyrimethamine is a synthetic antifolate antiparasitic drug that inhibits dihydrofolate reductase, disrupting folate metabolism and DNA synthesis in protozoan parasites such as Plasmodium species and Toxoplasma gondii.[1][2] Developed in the early 1950s by Gertrude Elion and George Hitchings at Burroughs Wellcome as part of rational drug design efforts targeting folate pathways, it was introduced for medical use in 1953 and contributed to Nobel Prize recognition for its creators in 1988 for advancements in chemotherapy.[3][4] It is employed primarily in combination with sulfonamides, such as sulfadiazine for toxoplasmosis in immunocompromised patients or sulfadoxine for chloroquine-resistant falciparum malaria, though widespread resistance has limited its standalone efficacy against malaria parasites.[5][6][7] Common adverse effects include dose-dependent bone marrow suppression leading to megaloblastic anemia, leukopenia, or thrombocytopenia, necessitating folinic acid supplementation and hematologic monitoring during therapy.[8][9]