Sulfadiazine + Trimethoprim

Oral
Urinary tract infections

Hypersensitivity; severe renal/hepatic impairment; blood dyscrasias, porphyrias, serious hematological disorders; megaloblastic anemia secondary to folate depletion. Infants ≤2 mth; pregnancy (at term), lactation.

Elderly, adequate fluid intake, G6PD deficiency, AIDS; actual or possible folate deficiency, child with fragile X chromosome associated with mental retardation; discontinue in case of skin rash; perform regular hematological examination.

Nausea, vomiting, anorexia and diarrhoea. Hypersensitivity, skin reactions; lumbar pain, haematuria, oliguria, anuria, crystallisation in urine, thrombocytopaenia, leucopaenia, eosinophilia, neonatal jaundice and kernicterus.
Potentially Fatal: Stevens-Johnson syndrome; agranulocytosis, thrombocytopaenia, jaundice in new born. Mild GI disturbances; pruritus; skin rash; sulfonamide-like skin reactions; disturbances of liver enzyme values, cholestatic jaundice; raised serum creatinine and BUN; fever; anaphylaxis; aseptic meningitis; hematologic disturbances; photosensitivity; induce hyperkalemia particularly in HIV patients being treated for Pneumocystis carinii pneumonia or in the elderly.

Sulphadiazine: Potentiates antidiabetic effect of sulphonylureas. Action antagonised by para-aminobenzoinc acid and procaine group of local anaesthetics.
Trimethoprim: Potentiate effects of phenytoin, digoxin, procainamide, warfarin. Reduces renal excretion of zalcitabine, zidovudine and lamivudine. Dapsone; rifampicin; increase risk of nephrotoxicity when given with cyclosporin; severe hyperkalaemia when given with ACE inhibitor; depressants of bone marrow function; risk of megaloblastic anemia with other folate inhibitors eg pyrimethamine, methotrexate; hyponatraemia if receiving diuretics concurrently.
Potentially Fatal: Potentiates oral anticoagulants, methotrexate and phenytoin. Ascorbic acid and hexamine may precipitate crystalluria; metabolism of oral hypoglycaemics may be inhibited.

Avoid vit C or acidifying agents to prevent crystalluria.

Interferes with estimation of urinary glucose, urobilinogen, urea and creatinine. May interfere with serum methotrexate assay where dihydrofolate reductase is used. Jaffe reaction for creatinine.

Description:
Mechanism of Action: Sulphadiazine is a short-acting sulphonamide derivative with bacteriostatic action through competitive inhibition of bacterial synthesis of folic acid. Trimethoprim inhibits enzymes folic acid pathway, preventing the reaction of the dihydrolic acid to tetrahydrofolate.

Antibacterial Combinations