Drug Characteristics
  • Formulation

    Tablet: 500 mg

  • Dose

    Toxoplasmosis treatment:

    1–2g (15 mg/kg) orally four times a day for up to 6 weeks (in combination with pyrimethamine).

    Toxoplasmosis maintenance:

    500 mg orally four times a day (or 1 g twice a day) in combination with pyrimethamine

  • Side Effects

    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

    Other information

    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

  • Interactions

    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

  • Renal

    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

  • Hepatic

    No data

  • Pregnancy

    Human Data Suggest Risk in 3 rd Trimester

  • Other Information