Sulphadiazine + Trimethoprim

Indications

Sulphadiazine + Trimethoprim is used for: UTI

Adult Dose

Oral Urinary tract infections Adult: Per tablet contains sulfadiazine 410 mg and trimethoprim 90 mg or per 5 mL suspension contains sulfadiazine 205 mg and trimethoprim 45 mg: 2 tablets or 20 mL as a single dose every 24 hr. Child: >3 mth: Per day: 14 mg sulfadiazine/kg+3 mg trimethoprim/kg. Daily dose is divided into 2 equal doses given every 12 hr.

Child Dose

Oral Urinary tract infections Child: >3 mth: Per day: 14 mg sulfadiazine/kg+3 mg trimethoprim/kg. Daily dose is divided into 2 equal doses given every 12 hr.

Renal Dose

Administration

Contra Indications

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

Precautions

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.

Pregnancy-Lactation

Interactions

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.

Adverse Effects

Side effects of Sulphadiazine + Trimethoprim : 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.

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.