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Pyrimethamine

    Brands

    DEA Class; Rx

    Common Brand Names; Daraprim

    • Antimalarials; 
    • Antiparasitic Agents

    Synthetic antiparasitic agent with slow schizonticidal activity
    Used for the treatment of toxoplasmosis in combination with sulfadoxine
    Only available through the DARAPRIM Direct Program

    Indicated for

    • Toxoplasmosis
    • P jiroveci Pneumonia (Off-label)
    • Prophylaxis p P jiroveci pneumonia (formerly Pneumocystis pneumonia); administer with dapsone
    • Treatment of GM-2 gangliosidoses (Tay-Sachs disease and Sandhoff disease)

    Hypersensitivity

    Megaloblastic or folate-deficiency anemia

    • Abdominal cramps
    • Abnormal skin pigmentation
    • Anaphylaxis
    • Anorexia
    • Arrhythmias (large doses)
    • Atrophic glossitis
    • Depression
    • Fever
    • Insomnia
    • Lightheadedness
    • Malaise
    • Seizures
    • Dermatitis
    • Erythema multiforme
    • Rash
    • Stevens-Johnson syndrome
    • Vomiting
    • Diarrhea
    • Xerostomia
    • Megaloblastic anemia
    • Leukopenia
    • Pancytopenia
    • Thrombocytopenia
    • Pulmonary eosinophilia
    • Neutropenia

    Use with caution in patients with G6PD deficiency

    Use with caution in hepatic/renal impairment and history of seizure disorders

    Dosage of pyrimethamine required for treatment of toxoplasmosis. has a narrow therapeutic window; if signs of folate deficiency develop, reduce dosage or discontinue drug according to response of patient; folinic acid (leucovorin) should be administered in a dosage of 5 to 15 mg daily (orally, IV, or IM) until normal hematopoiesis restored

    Megaloblastic anemia, leukopenia, thrombocytopenia, neutropenia, and pancytopenia reported with high doses; monitor CBC and platelets twice weekly in patients receiving high dose therapy

    Use caution in patients with possible folate deficiency, including pregnancy, malabsorption syndrome, and alcoholism

    Administer with leucovorin, especially at high doses, to prevent hematologic complications, due to pyrimethamine-induced folic acid deficiency; continue leucovorin during therapy and for 1 week after discontinuing therapy

    Pregnancy Category: C

    Lactation: enters breast milk, do not nurse

    Adults

    75 mg/day PO.

    Geriatric

    75 mg/day PO.

    Adolescents

    75 mg/day PO.

    Children

    1 mg/kg/day is FDA-approved maximum dosage; however, doses up to 2 mg/kg/day (Max: 50 mg/day) are used off-label.

    Infants

    1 mg/kg/day is FDA-approved maximum dosage; however, doses up to 2 mg/kg/day are used off-label.

    Neonates

    1 mg/kg/day is FDA-approved maximum dosage; however, doses up to 2 mg/kg/day are used off-label.

    Pyrimethamine

    tablet

    • 25mg