Co-trimoxazole = Sulfamethoxazole (SMX)/Trimethoprim (TMP) oral

Therapeutic action

Combination of two antibacterials: a sulfonamide, sulfamethoxazole, and a diaminopyrimidine antifolate, trimethoprim.

Indications

• Treatment of cerebral toxoplasmosis, pneumocystosis, isosporiasis, cyclosporiasis, and brucellosis.
• Prophylaxis of pneumocystosis, toxoplasmosis, and isosporiasis.
• Second-line treatment of pertussis.
• Uncomplicated typhoid fever if the strain is susceptible with a recent drug susceptibility test.

Forms and strengths

• 400 mg SMX/80 mg TMP and 800 mg SMX/160 mg TMP tablets.
• 100 mg SMX/20 mg TMP dispersible tablet.

Dose

Duration

• Cyclosporiasis: 7 days.
• Isosporiasis: 7 to 10 days.
• Typhoid fever and pertussis: 14 days.
• Pneumocystosis: 21 days.
• Cerebral toxoplasmosis: 4 to 6 weeks.
• Brucellosis: 6 weeks.

Contra-indications, adverse effects, precautions

• Do not administer to children under 6 weeks except for the treatment and prophylaxis of pneumocystosis.
• Do not administer to patients with severe renal or hepatic impairment or with a history of hypersensitivity to sulfonamides.
• May cause haemolytic anaemia in patients with G6PD deficiency, thrombocytopenia, leucopenia, agranulocytosis, and megaloblastic anaemia due to folic acid deficiency.
• May cause hypersensitivity reactions including severe cutaneous reactions. Early symptoms such as fever, rash, mouth ulcers, and bleeding require immediate medical attention. In all these cases, stop treatment immediately.
• May also cause gastrointestinal disturbances, hepatic or renal disorders, metabolic disorders such as hyperkalaemia, hypoglycaemia, hyponatraemia, neuropathy, and photosensitivity.
• In the event of prolonged treatment, monitor full blood count if possible.
• Avoid or monitor combinations with drugs inducing hyperkalaemia, phenytoin, zidovudine, and antidiabetics.
• Drink plenty of water during treatment to reduce the risk of crystalluria.
• Pregnancy: there is a risk of congenital malformations in the first trimester and neonatal haemolysis and hyperbilirubinaemia after 36 weeks. For prophylaxis and treatment of pneumocystosis in HIV-exposed and HIV-infected women, the benefits outweigh the risks.
• Breast-feeding: avoid in women breastfeeding neonates or vulnerable infants. If used, observe the child for signs of anaemia or jaundice.