Pirimecidan - General Information
One of the folic acid antagonists that is used as an antimalarial or with a sulfonamide to treat toxoplasmosis. [PubChem]
Pharmacology of Pirimecidan
Pirimecidan is an antiparasitic compound commonly used as an adjunct in the treatment of uncomplicated, chloroquine resistant, P. falciparum malaria. Pirimecidan 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. Pirimecidan 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.
Pirimecidan 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.
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.
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.
Additional information about Pirimecidan
Pirimecidan Indication: For the treatment of toxoplasmosis and acute malaria; For the prevention of malaria in areas non-resistant to pyrimethamine
Mechanism Of Action: Pirimecidan inhibits the dihydrofolate reductase of plasmodia and thereby blocks the biosynthesis of purines and pyrimidines, which are essential for DNA synthesis and cell multiplication. This leads to failure of nuclear division at the time of schizont formation in erythrocytes and liver.
Drug Interactions: Not Available
Food Interactions: Not Available
Generic Name: Pyrimethamine
Synonyms: Pyrimethamine Hcl; Pyrimethamin; Pyremethamine; Ethylpyrimidine; Diaminopyritamin; CD; Chloridin; Chloridine; Primethamine; Pirimetamina; Pirimetamin; Chloridyn
Drug Category: Antiprotozoals; Antimalarials; Folic Acid Antagonists
Drug Type: Small Molecule; Approved
Absorption: Well absorbed with peak levels occurring between 2 to 6 hours following administration
Toxicity (Overdose): Not Available
Protein Binding: 87%
Half Life: 96 hours
Dosage Forms of Pirimecidan: Tablet Oral
Chemical IUPAC Name: 5-(4-chlorophenyl)-6-ethylpyrimidine-2,4-diamine
Chemical Formula: C12H13ClN4
Pyrimethamine on Wikipedia: https://en.wikipedia.org/wiki/Pyrimethamine
Organisms Affected: Plasmodium