Sulfamethoxazole

Oral
Urinary tract infections, Otitis media, Chlamydial infections, Prophylaxis of meningococcal meningitis

Dose reduction in renal impairment

Should be taken on an empty stomach.

Severe renal or hepatic impairment, blood disorders, hypersensitivity to sulfonamides, porphyria, SLE, infants <2 mth, pregnancy (3rd trimester) and lactation.

Renal or hepatic impairment, history of allergy or asthma, AIDS, G6PD deficiency, elderly, ensure adequate fluid intake to reduce risk of crystalluria. Pregnancy.

Nausea, vomiting, anorexia, diarrhoea, hypersensitivity reactions, blood disorders, serum sickness-like syndrome, hypoglycaemia, hypothyroidism, pseudomembranous colitis, kernicterus in premature neonates.

IV/Parenteral/PO: D

Concurrent use increases phenytoin and methotrexate levels; increased risk of bleeding with warfarin and acenocoumarol; may potentiate antidiabetic effect of sulphonylureas.
Potentially Fatal: Concurrent use increased risk of blood dyscrasias with clozapine and pyrimethamine.

Interference with tests for urea, creatinine, urinary glucose, urobilinogen.

Description:
Mechanism of Action: Sulfamethoxazole is an intermediate-acting sulfonamide which interferes with the synthesis of nucleic acids in sensitive organisms by blocking the conversion of PABA to the coenzyme dihydrofolic acid. Its action is bacteriostatic, although it can be bactericidal where concentrations of thymine are low in the surrounding medium. It has broad spectrum of action though its usefulness has been greatly reduced by widespread resistance.

Sulphonamides