GENERIC AVAILABLE: No
PREPARATIONS: Tablets: 25 mg.
STORAGE: Pyrimethamine tablets should be stored between 15 C and 25 C (59 F and 77 F).
- Toxoplasmosis treatment: For the treatment of toxoplasmosis the recommended adult starting dose is 50 to 75 mg of daily with 1 to 4 g daily of a sulfonamide for 1 to 3 weeks depending on the response of the patient and tolerance to therapy. The dosage of each drug should be reduced by half then continued for an additional 4 to 5 weeks.
- Acute malaria treatment: For treatment of acute malaria the dose is 25 to 50 mg daily for 2 days with a sulfonamide though chloroquine or quinine are preferred for treatment of acute malaria.
- Malaria prevention: For preventing malaria the recommended dose for adults and children over 10 years of age is 25 mg once weekly, and for children 4 through 10 years of age the dose is 12.5 mg (1/2 tablet) once weekly. Infants and children under 4 years of age should receive 6.25 mg (1/4 tablet) once weekly.
DRUG INTERACTIONS: Combining pyrimethamine with other drugs that block folic acid or drugs that suppress the bone marrow may increase the risk of bone marrow suppression. Examples include sulfonamides or trimethoprim-sulfamethoxazole combinations, proguanil, zidovudine (Retrovir), or methotrexate (Trexall). If signs of folate deficiency develop, pyrimethamine should be discontinued and folinic acid (leucovorin) should be administered until normal bone marrow function is restored.
PREGNANCY: There are no adequate studies of pyrimethamine in pregnant women. Pyrimethamine should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus. Folic acid should also be given if it is used for the treatment of toxoplasmosis during pregnancy.
NURSING MOTHERS: Pyrimethamine is secreted in breast milk. Women should not nurse while taking pyrimethamine.
REFERENCE: FDA Prescribing Information
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