Why Is Fansidar Prescribed?
One of the folic acid antagonists that is used as an antimalarial or with a sulfonamide to treat toxoplasmosis.
Pharmacology:
Fansidar is an antiparasitic compound commonly used as an adjunct in the treatment of uncomplicated, chloroquine resistant, P. falciparum malaria. Fansidar is a folic acid antagonist and the rationale for its therapeutic action is based on the differential requirement between host and parasite for nucleic acid precursors involved in growth. This activity is highly selective against plasmodia and Toxoplasma gondii. Fansidar possesses blood schizonticidal and some tissue schizonticidal activity against malaria parasites of humans. However, the 4-amino-quinoline compounds are more effective against the erythrocytic schizonts. It does not destroy gametocytes, but arrests sporogony in the mosquito. The action of pyrimethamine against Toxoplasma gondii is greatly enhanced when used in conjunction with sulfonamides.
Fansidar for patients
Patients should be warned that at the first appearance of a skin rash they should stop use of Pyrimethamine and seek medical attention immediately. Patients should also be warned that the appearance of sore throat, pallor, purpura, or glossitis may be early indications of serious disorders which require treatment with Pyrimethamine to be stopped and medical treatment to be sought.
Women of childbearing potential who are taking Pyrimethamine should be warned against becoming pregnant. Patients should be warned to keep DARAPRIM out of the reach of children. Patients should be advised not to exceed recommended doses. Patients should be warned that if anorexia and vomiting occur, they may be minimized by taking the drug with meals.
Concurrent administration of folinic acid is strongly recommended when used for the treatment of toxoplasmosis in all patients.
Fansidar Interactions
Pyrimethamine may be used with sulfonamides, quinine and other antimalarials, and with other antibiotics. However, the concomitant use of other antifolic drugs or agents associated with myelosuppression including sulfon-amides or trimethoprim-sulfamethoxazole combinations, proguanil, zidovudine, or cytostatic agents (e.g., methotrex-ate) while the patient is receiving pyrimethamine, may increase the risk of bone marrow suppression. If signs of folate deficiency develop, pyrimethamine should be discontinued. Folinic acid (leucovorin) should be administered until normal hematopoiesis is restored. Mild hepatotoxicity has been reported in some patients when lorazepam and pyrimethamine were administered concomitantly.
Fansidar Contraindications
Use of DARAPRIM is contraindicated in patients with known hypersensitivity to pyrimethamine or to any component of the formulation. Use of the drug is also contraindicated in patients with documented megaloblastic anemia due to folate deficiency.