Formulary
Sulfadiazine: Indications, Dosing, Side Effects and Interactions
Sulfadiazine is a short-acting sulphonamide with bacteriostatic activity against a broad spectrum of organisms.
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Sulfadiazine: Indications, Dosing, Side Effects and Interactions
Sulfadiazine is a short-acting sulphonamide with bacteriostatic activity against a broad spectrum of organisms.
Drug action
Sulfadiazine is a short-acting sulphonamide with bacteriostatic activity against a broad spectrum of organisms. The importance of the sulfonamides has decreased as a result of increasing bacterial resistance and their replacement by antibacterials which are generally more active and less toxic.
Indications and dose
**Prevention of rheumatic fever recurrence**
- **Adult** (By Mouth): (body-weight 30 kg and above) 1 g daily.
**Toxoplasmosis in pregnancy (in combination with pyrimethamine and folinic acid) for sulfadiazine**
- **Child 12-17 years** (By mouth): 1 g 3 times a day until delivery.
**Congenital toxoplasmosis (in combination with pyrimethamine and folinic acid) for sulfadiazine**
- **Neonate** (By mouth): 50 mg/kg twice daily for 12 months.
Cautions
Asthma; avoid in blood disorders; elderly; G6PD deficiency (risk of haemolytic anaemia); maintain adequate fluid intake; predisposition to folate deficiency
Contraindications
Acute porphyrias
Side effects
Rare or very rare Haemolytic anaemia Frequency not known Agranulocytosis; aplastic anaemia; appetite decreased; ataxia; back pain; blood disorders; cough; crystalluria; cyanosis; depression; diarrhoea; dizziness; drowsiness; dyspnoea; eosinophilia; erythema nodosum; fatigue; fever; haematuria; hallucination; headache; hepatic disorders; hypoglycaemia; hypoprothrombinaemia; hypothyroidism; idiopathic intracranial hypertension; idiopathic pulmonary fibrosis; insomnia; leucopenia; meningitis aseptic; myocarditis; nausea; nephritis tubulointerstitial; nephrotoxicity; nerve disorders; neurological effects; neutropenia; oral disorders; pancreatitis; photosensitivity reaction; pseudomembranous enterocolitis; psychosis; pulmonary eosinophilia; renal impairment; renal tubular necrosis; seizure; serum sickness-like reaction; severe cutaneous adverse reactions (SCARs); skin reactions; systemic lupus erythematosus (SLE); thrombocytopenia; tinnitus; vasculitis; vertigo; vomiting Side-effects, further information Discontinue immediately if blood disorders (including leucopenia, thrombocytopenia, megaloblastic anaemia, eosinophilia) or rash (including Stevens-Johnson syndrome, toxic epidermal necrolysis) develop.
Interactions
**Other interactions (13):**
- Anti-infectives: Like other sulphonamides, Sulfadiazine demonstrated synergy with the difolate reductase release inhibitors, pyrimethamine and trimethoprim.
- Risk of pancytopenia and megloblastic anaemia with concurrent pyrimethamine.
- Anticoagulants: sulphonamides may potentiate the effects of coumarins, such as warfarin.
- Antidiabetics: antidiabetic effect of sulphonylureas, e.g.
- Antiepileptics: sulphonamides may potentiate the effect of phenytoin.
- Antipsychotics: avoid concurrent clozapine (increased risk of agranulocytosis); see Section 4.3.
Pregnancy
Risk of neonatal haemolysis and methaemoglobinaemia in third trimester; fear of increased risk of kernicterus in neonates appears to be unfounded.
Breast feeding
Small risk of kernicterus in jaundiced infants and of haemolysis in G6PD-deficient infants.
Hepatic impairment
Manufacturer advises caution in mild to moderate impairment; avoid in severe impairment or jaundice.
Renal impairment
Caution in mild to moderate impairment; avoid in severe impairment (risk of crystalluria). M Dose adjustments Dose reduction may be necessary. M
Medicinal forms
Suspension
Clinical governance
**Author:** MedNext Clinical Team. **Clinical reviewer:** Dr Shameer Deen, MBBS, MS, MRCS. **Sources:** BNF, Indian Pharmacopoeia, CIMS India. **Correction:** Report errors at support@mednext.academy.
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