Sulfadoxine/pyrimethamine

Sulfadoxine/pyrimethamine, sold under the brand name Fansidar, is a combination medication used to treat malaria.[1] It contains sulfadoxine (a sulfonamide) and pyrimethamine (an antiprotozoal). For the treatment of malaria it is typically used along with other antimalarial medication such as artesunate. In areas of Africa with moderate to high rates of malaria, three doses are recommended during the second and third trimester of pregnancy.[2]

Side effects include diarrhea, rash, itchiness, headache, and hair loss. Rarely a severe allergic reaction or rash such as toxic epidermal necrolysis, may occur. It is not generally recommended in people with a sulfonamide allergy or significant liver or kidney disease.[3] It works by blocking malaria's ability to use folinic acid.

Sulfadoxine/pyrimethamine was initially approved for medical use in the United States in 1981. It is on the World Health Organization's List of Essential Medicines.[4] It is not commercially available in the United States.[5]

Medical uses

Adverse effects

Adverse effects by incidence include:[15][16][17][18]

Common (>1% frequency):

Rare (<1% frequency):

Unknown frequency:

• Hypersensitivity reactions (e.g. itchiness, contact dermatitis, and hives)
• Myelosuppression
• Gastrointestinal effects (e.g. nausea, vomiting, and diarrhoea)
• Headache

• Stevens–Johnson syndrome
• Toxic epidermal necrolysis
• Agranulocytosis
• Aplastic anaemia
• Disorder of haematopoietic structure
• Drug-induced eosinophilia
• Thrombocytopaenia
• Liver necrosis
• Hepatitis
• Jaundice
• Hepatomegaly
• Nephrotoxicity

• Weight loss
• Abdominal cramps
• Hair loss
• Photosensitivity
• Fatigue
• Fever
• Polyneuritis
• Atrophic glossitis
• Gastritis

• Abnormal liver function test results (e.g. elevated serum ALT, AST, alkaline phosphatase, and bilirubin concentrations)

Pharmacology

Sulfadoxine is a sulfonamide antibiotic that competes with p-aminobenzoic acid in the biosynthesis of folate.[15] Pyrimethamine serves as a selective inhibitor of protozoal dihydrofolate reductase, hence preventing the synthesis of tetrahydrofolate — the active form of folate.[15] A great degree of synergy occurs between the two drugs due to their inhibition of two different steps in the biosynthesis of tetrahydrofolate.[15]