Daraprim

Pyrimethamine

Clinical data
Pronunciation	/ˌpɪrᵻˈmɛθəmin/
Trade names	Daraprim
AHFS/Drugs.com	Monograph
MedlinePlus	a601050
Pregnancy category	AU: B3 US: C (Risk not ruled out)
Routes of administration	By mouth
ATC code	P01BD01 (WHO) QP51AX51 (WHO) (combinations)
Legal status
Legal status	AU: S4 (Prescription only) CA: ℞-only UK: POM (Prescription only) US: ℞-only
Pharmacokinetic data
Bioavailability	well-absorbed
Protein binding	87%
Metabolism	Liver
Biological half-life	96 hours
Excretion	Kidney
Identifiers
IUPAC name 5-(4-chlorophenyl)-6-ethyl- 2,4-pyrimidinediamine
CAS Number	58-14-0 Y
PubChem CID	4993
IUPHAR/BPS	4800
DrugBank	DB00205 Y
ChemSpider	4819 Y
UNII	Z3614QOX8W
KEGG	D00488 Y
ChEBI	CHEBI:8673 Y
ChEMBL	CHEMBL36 Y
PDB ligand	CP6 (PDBe, RCSB PDB)
ECHA InfoCard	100.000.331
Chemical and physical data
Formula	C12H13ClN4
Molar mass	248.71 g/mol
3D model (JSmol)	Interactive image
Melting point	233 to 234 °C (451 to 453 °F)
SMILES Clc2ccc(c1c(nc(nc1CC)N)N)cc2
InChI InChI=1S/C12H13ClN4/c1-2-9-10(11(14)17-12(15)16-9)7-3-5-8(13)6-4-7/h3-6H,2H2,1H3,(H4,14,15,16,17) Y Key:WKSAUQYGYAYLPV-UHFFFAOYSA-N Y

Pyrimethamine, sold under the trade name Daraprim, is a medication used with leucovorin to treat toxoplasmosis and cystoisosporiasis. It is also used with dapsone as a second line option to prevent Pneumocystis jiroveci pneumonia (PCP) in people with HIV/AIDS. It was previously used for malaria but is no longer recommended due to resistance. Pyrimethamine is taken by mouth.

Common side effects include gastrointestinal upset, severe allergic reactions, bone marrow suppression. It should not be used by people with folate deficiency that has resulted in anemia. There is concern that it may increase the risk of cancer. While occasionally used in pregnancy it is unclear if pyrimethamine is safe for the baby. Pyrimethamine is classified as a folic acid antagonist. It works by inhibiting folic acid metabolism and therefore the making of DNA.

Pyrimethamine was discovered in 1952 and came into medical use in 1953. It is on the World Health Organization's List of Essential Medicines, the most effective and safe medicines needed in a health system. In the United States in 2015 it was not available as a generic medication and the price was increased from 13.50 USD to 750 USD a tablet (75,000 USD for a course of treatment). In other areas of the world it is available as a generic and costs as little as 0.05 to 0.10 USD per dose.

Pyrimethamine is typically given with a sulfonamide and folinic acid.