Sulfadiazine information from DrugsUpdate  

Pharmacodynamics

Pharmacokinetics

Sulfadiazine is a short-acting sulfonamide derivative with bacteriostatic action through competitive inhibition of bacterial synthesis of folic acid. Susceptible organisms include E.coli, Klebsiella, Enterobacter, Proteus mirabilis, P.vulgaris, S.aureus, Toxoplasma, N.meningitidis, H.influenzae.

Absorption
Readily absorbed from the GI tract. Blood concentrations peak 3-6 hours after a single dose.

Distribution
20-55% bound to plasma proteins. Distributes into CSF within 4 hours of an oral dose.

Excretion
Half-life: About 10 hours; prolonged in renal impairment. About 50% of a single oral dose is excreted in the urine within 24 hours.

Sulfadiazine Indications / Sulfadiazine Uses

Information Not Available

Sulfadiazine Adverse Reactions / Sulfadiazine Side Effects

Nausea, vomiting, anorexia and diarrhoea. Hypersensitivity, skin reactions; lumbar pain, haematuria, oliguria, anuria, crystallisation in urine, thrombocytopenia, leucopenia, eosinophilia, neonatal jaundice and kernicterus.

Potentially Fatal: Stevens-Johnson syndrome; agranulocytosis, thrombocytopenia, jaundice in newborn.

Precautions

Sulfonamides should be given with caution to patients with impaired renal or hepatic function and to those with severe allergy or bronchial asthma.

Hemolysis may occur in individuals deficient in glucose-6-phosphate dehydrogenase. This reaction is dose related.

Adequate fluid intake must be maintained in order to prevent crystalluria and stone formation.

Special Precautions

Elderly, maintain adequate fluid intake to reduce risk of crystalluria, G6PD deficiency, AIDS. Renal/hepatic impairment, history of allergy or asthma. Discontinue treatment if patient develops rash. Conduct CBC and urinalyses using microscopic examination during prolonged therapy. May exacerbate lupus erythematosus. Infants <2 months.

Other Drug Interactions

Potentiates antidiabetic effect of sulphonylureas. Action antagonised by PABA and procaine group of local anaesthetics. Potentiates oral anticoagulants, methotrexate and phenytoin. May decrease serum levels of ciclosporin. Ascorbic acid and hexamine may increase risk of crystalluria.

Other Interactions

Information Not Available

Dosage

Oral
Susceptible infections
Adult: Initially, 2-4 g/day. May increase up to 6 g/day, given in divided doses.
Child: Start with 75 mg/kg, subsequently, 150 mg/kg in divided doses. Max: 6 g/day.
Renal impairment: Dosage reduction may be necessary.

Oral
Prophylaxis of rheumatic fever
Adult: >30 kg: 1 g once daily; <30 kg: 500 mg once daily.
Child: <30 kg: 0.5 g every 24 hours; >30 kg: 1 g/day.
Renal impairment: Dosage reduction may be necessary.

Oral
Nocardiosis
Adult: 4-8 g daily for at least 6 weeks. May continue for many months to prevent relapse of infection.
Renal impairment: Dosage reduction may be necessary.

Oral
Toxoplasmosis
Adult: Including immunocompromised patients: 4-6 g/day in 4 divided doses for at least 6 weeks. Subsequently, 2-4 g/day, to be continued indefinitely.
Child: For congenital toxoplasmosis: <2 months: 50 mg/kg bid for 12 months.
Renal impairment: Dosage reduction may be necessary.

Oral
Prophylaxis of toxoplasmosis in patients with HIV infection
Adult: 0.5-1 g every 6 hours, to be taken with oral pyrimethamine (25-50 mg daily) and oral leucovorin (10-25 mg/day).
Child: 85-120 mg/kg/day, given in 2-4 divided doses with oral pyrimethamine (1 mg/kg/day; max: 25 mg/day) and oral leucovorin (5 mg once every 3 days).
Renal impairment: Dosage reduction may be necessary.

Food(before/after)

Information Not Available

Sulfadiazine and Pregnancy

Contraindicated in pregnancy

Category C: Either studies in animals have revealed adverse effects on the foetus (teratogenic or embryocidal or other) and there are no controlled studies in women or studies in women and animals are not available. Drugs should be given only if the potential benefit justifies the potential risk to the foetus.

If administered near term.

Category D: There is positive evidence of human foetal risk, but the benefits from use in pregnant women may be acceptable despite the risk (e.g., if the drug is needed in a life-threatening situation or for a serious disease for which safer drugs cannot be used or are ineffective).

Sulfadiazine and Lactation

Contraindicated in lactation

Sulfadiazine and Children

Contraindicated in children under 2 months of age (except as adjunctive therapy with pyrimethamine in treating toxoplasmosis).

Sulfadiazine and Geriatic

Information Not Available

Sulfadiazine and Other Contraindications

Hypersensitivity; severe renal/hepatic impairment, blood dyscrasias, porphyrias, pregnancy (at term), lactation.

Storage

Information Not Available

Lab interference

Information Not Available