Metoprine is primarily used as an antiparasitic agent, particularly in the treatment of toxoplasmosis and malaria. It works by inhibiting the enzyme dihydrofolate reductase, which is crucial for the synthesis of nucleic acids in parasites, thereby preventing their growth and replication. In veterinary medicine, it is employed to control parasitic infections in animals. Additionally, Metoprine has been explored for its potential use in cancer therapy due to its ability to interfere with folate metabolism, which is vital for rapidly dividing cancer cells. Its application in research also extends to studying folate-dependent processes in various biological systems.