Sulfadiazine

Oral
Susceptible infections
Adult: Initially, 2-4 g, followed by 2-4 g daily in in 3-6 divided doses. Max treatment duration: 7 days.
Child: Initially, 0.075 g/kg, followed by 0.150 g/kg daily in 4-6 divided doses. Max: 6 g daily.
Renal impairment: Mild to moderate: Dosage reduction may be necessary. Severe: Contraindicated.
Hepatic impairment: Severe: Contraindicated.

Oral
Prophylaxis of rheumatic fever
Adult: ≤30 kg: 0.5 g once daily; >30 kg: 1 g once daily.
Child: ≤30 kg: 0.5 g daily; >30 kg: 1 g daily.
Renal impairment: Mild to moderate: Dosage reduction may be necessary. Severe: Contraindicated.
Hepatic impairment: Severe: Contraindicated.

Oral
Toxoplasmosis
Adult: As adjunctive therapy w/ pyrimethamine: 4-6 g daily in 4 divided doses for at least 6 wk. Suppressive dose: 2-4 g daily, to be continued indefinitely.
Child: For congenital toxoplasmosis: As adjunctive therapy w/ pyrimethamine: <2 mth: 0.05 g/kg bid for 12 mth.
Renal impairment: Mild to moderate: Dosage reduction may be necessary. Severe: Contraindicated.
Hepatic impairment: Severe: Contraindicated.

May be taken with or without food. Should be taken w/ a full glass of water (240 mL) w/ each dose of medication & at frequent intervals throughout the day.

Hypersensitivity to sulfonamides. Acute porphyria, blood disorders, jaundice. Severe renal or hepatic impairment. Infants <2 mth (except in the treatment of toxoplasmosis). Pregnancy and lactation. Concomitant use w/ clozapine.

Patient w/ G6PD deficiency, history of allergy or asthma, AIDS, lupus erythematosus, predisposition to folate deficiency. Mild to moderate hepatic and renal impairment. Childn. Patient Counselling Maintain adequate fluid intake. Monitoring Parameters Perform culture and sensitivity test prior to initiation of therapy. Monitor CBC and urinalysis (during therapy), CD4+ count in HIV-exposed/+ve patients treated for toxoplasmosis.

Significant: Bacterial or fungal superinfection (prolonged use). Nervous: Headache, convulsions, hallucinations, mental depression, ataxia, insomnia, vertigo, peripheral neuritis. GI: Diarrhoea, nausea, vomiting, anorexia, abdominal pain, pancreatitis, stomatitis. Hepatic: Hepatitis, neonatal jaundice and kernicterus. Genitourinary: Crystalluria, anuria, oliguria. Haematologic: Eosinophilia, leucopenia, thrombocytopenia. Otic: Tinnitus. Dermatologic: Rash, skin reactions.
Potentially Fatal: Stevens-Johnson syndrome, toxic epidermal necrolysis; blood dyscrasias (e.g. agranulocytosis, aplastic anaemia), hepatic necrosis.

Symptoms: Diarrhoea, nausea. Management: Symptomatic treatment. Continuous forced fluids and urine should be rendered alkaline.

May enhance the hypoglycaemic effect of sulfonylureas. Action antagonised by PABA and procaine group of local anaesthetics. May potentiate the effects of oral anticoagulants (e.g. warfarin), methotrexate, phenytoin, thiopentone anaesthetics. May decrease serum levels of ciclosporin. Increased risk of toxicity w/ aspirin. Increased risk of crystalluria w/ diuretics. May reduce the effect of oestrogen-containing OCs.
Potentially Fatal: Increased risk of agranulocytosis when given w/ clozapine.

Acidic preparations (e.g. cranberry juice) may cause crystalluria.

Interferes w/ estimation of urinary glucose, urobilinogen, urea and creatinine.

Sulfadiazine is a short-acting sulfonamide derivative w/ bacteriostatic action through competitive inhibition of bacterial synthesis of folic acid.
Absorption: Readily absorbed from the GI tract. Time to peak plasma concentration: 3-6 hr.
Distribution: Distributed into body tissues and fluids, including CSF. Crosses the placenta and enters breast milk. Plasma protein binding: 20-55%.
Metabolism: Metabolised via N-acetylation.
Excretion: Via urine (43-60% as unchanged drug, 15-40% as metabolites). Elimination half-life: Approx 10 hr.

Oral: Store between 20-25°C. Protect from light.

Sulphonamides

J01EC02 - sulfadiazine ; Belongs to the class of intermediate-acting sulfonamides. Used in the systemic treatment of infections.