Pyrimethamine, sold under the brand name Daraprim among others, is a medication used with leucovorin to treat the parasite diseases toxoplasmosis and cystoisosporiasis. It is also used with dapsone as a second-line option to prevent Pneumocystis jiroveci pneumonia in people with HIV/AIDS. It was previously used for malaria but is no longer recommended due to resistance. [Source: Wikipedia 
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