Tablet: 500 mg
1–2g (15 mg/kg) orally four times a day for up to 6 weeks (in combination with pyrimethamine).
500 mg orally four times a day (or 1 g twice a day) in combination with pyrimethamine
Rash (rarely Stevens–Johnson syndrome); haemolytic anaemia especially in patients with G6PD deficiency; other blood dyscrasias (agranulocytosis, aplastic anaemia, leukopenia and thrombocytopenia); crystaluria; renal toxicity; raised LFTs (rarely hepatitis and jaundice); pancreatitis; gastrointestinal disturbances
Crystalluria can occur with sulfadiazine because of its low solubility. Adequate hydration will minimize the risk of this. A urine output of >1200ml per day should be maintained throughout treatment. If crystalluria occurs stop treatment and alkalize the urine using bicarbonate
Additive toxicity with other bone marrow suppressive and renally toxic drugs e.g. ganciclovir, zidovudine, and trimetrexate
Sulfadiazine is highly protein bound – effect of phenytoin and warfarin may be enhanced
Caution: avoid other sulphonamides – do not co-prescribe cotrimoxazole
Dose in renal impairment GFR (ml/min)
20–50: Dose as in normal renal function
10–20: Use 50% of dose and monitor levels.
<10: Use 25% dose and monitor levels
Human Data Suggest Risk in 3 rd Trimester