Trade Names:Daraprim- Tablets 25 mg
Pyrimethamine is a folic acid antagonist, and the therapeutic action is based on differential requirements between host and parasite for nucleic acid precursors involved in growth.
Well absorbed, reaching C max in 2 to 6 h.
Plasma protein binding is 87%.
Plasma t ½ is approximately 96 h.
Treatment of toxoplasmosis (in conjunction with a sulfonamide); treatment of acute malaria (in conjunction with a schizonticide [eg, chloroquine, quinine] but a sulfonamide [eg, sulfadoxine] will initiate transmission control and suppression of susceptible strains of plasmodia); chemoprophylaxis of malaria.
Patients with documented megaloblastic anemia caused by folate deficiency; hypersensitivity to any component of the product.
PO 50 mg/day for 2 days.Children 4 to 10 yr of age
PO 25 mg/day for 2 days. Follow with the once weekly chemoprophylaxis regimen described below. Regimens that include suppression should be extended through any characteristic periods of early recrudescence and late relapse (for at least 10 wk).Chemoprophylaxis of MalariaAdults and Children older than 10 yr of age
PO 25 mg once/wk.Children 4 to 10 yr of age
PO 12.5 mg once/wk.Infants and Children younger than 4 yr of age
PO 6.25 mg once/wk.ToxoplasmosisAdults
PO Start with 50 to 75 mg/day, together with 1 to 4 g of a sulfapyrimidine type sulfonamide (eg, sulfadoxine). Continue for 1 to 3 wk, depending on response and tolerance. Dosage may then be reduced to about one-half that previously given for each drug and continued for an additional 4 to 5 wk.Children
PO 1 mg/kg/day in 2 equally divided doses; after 2 to 4 days, reduce dose to one-half and continue for about 1 mo. Coadminister the usual pediatric sulfonamide dosage with pyrimethamine.
Administer prescribed dose with food to minimize anorexia and vomiting.
Store tablets at controlled room temperature (59° to 77°F). Protect from light and moisture.
May increase risk of bone marrow suppression.Lorazepam
Mild hepatotoxicity has been reported.
None well documented.
Anorexia; vomiting (with large doses); atrophic glossitis.
Megaloblastic anemia; leukopenia; thrombocytopenia; pancytopenia; hematuria.
Hypersensitivity (may include Stevens-Johnson syndrome, toxic epidermal necrolysis, erythema multiforme, anaphylaxis); pulmonary eosinophilia (rare).
Asses CBC, including platelet count, before starting therapy and semi-weekly thereafter in patient being treated for toxoplasmosis. If signs of folate deficiency develop (eg, megaloblastic changes, glossitis), discontinue pyrimethamine and administer folinic acid (leucovorin) until normal hematopoiesis is restored.
Category C .
Excretion in breast milk.
See Route/Dosage section.
Use with caution, usually starting at the low end of the dosing range because of the greater frequency of decreased hepatic, renal, or cardiac function, and concomitant diseases or other drug therapy.
Use with caution.
Use with caution.
Keep out of the reach of infants and children as they are extremely susceptible to adverse reactions from an overdose; death may occur.
The dose of pyrimethamine required to treat toxoplasmosis approaches the toxic level. Use with caution in possible folate deficiency.
Large doses may precipitate hemolytic anemia in patients with glucose-6-phosphate dehydrogenase deficiency.
Resistance to pyrimethamine is prevalent worldwide; it is not considered suitable as a prophylactic agent for travelers to most areas.
Convulsions, abdominal pain, nausea, severe and repeated vomiting (including hematemesis), CNS toxicity (manifested as excitability), generalized and prolonged convulsions, respiratory depression, circulatory collapse, death.
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