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.
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.
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.
Administration
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.
Contraindications
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.
Special Precautions
Patients w/ G6PD deficiency, history of allergy or asthma, AIDS, lupus erythematosus, predisposition to folate deficiency. Mild to moderate hepatic and renal impairment. Childn.
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.
Overdosage
Symptoms: Diarrhoea, nausea. Management: Symptomatic treatment. Continuous forced fluids and urine should be rendered alkaline.
Drug Interactions
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.
Food Interaction
Acidic preparations (e.g. cranberry juice) may cause crystalluria.
Lab Interference
Interferes w/ estimation of urinary glucose, urobilinogen, urea and creatinine.
Action
Description: Mechanism of Action: Sulfadiazine is a short-acting sulfonamide derivative w/ bacteriostatic action through competitive inhibition of bacterial synthesis of folic acid. Pharmacokinetics: 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.
Chemical Structure
Sulfadiazine Source: National Center for Biotechnology Information. PubChem Database. Sulfadiazine, CID=5215, https://pubchem.ncbi.nlm.nih.gov/compound/Sulfadiazine (accessed on Jan. 23, 2020)
J01EC02 - sulfadiazine ; Belongs to the class of intermediate-acting sulfonamides. Used in the systemic treatment of infections.
References
Anon. Sulfadiazine. Lexicomp Online. Hudson, Ohio. Wolters Kluwer Clinical Drug Information, Inc. https://online.lexi.com. Accessed 12/10/2017.Buckingham R (ed). Sulfadiazine. Martindale: The Complete Drug Reference [online]. London. Pharmaceutical Press. http://www.medicinescomplete.com. Accessed 12/10/2017.Joint Formulary Committee. Sulfadiazine. British National Formulary [online]. London. BMJ Group and Pharmaceutical Press. http://www.medicinescomplete.com. Accessed 12/10/2017.McEvoy GK, Snow EK, Miller J et al (eds). Sulfadiazine. AHFS Drug Information (AHFS DI) [online]. American Society of Health-System Pharmacists (ASHP). http://www.medicinescomplete.com. Accessed 12/10/2017.Sulfadiazine Tablet (Eon Labs, Inc.). DailyMed. Source: U.S. National Library of Medicine. https://dailymed.nlm.nih.gov/dailymed/. Accessed 12/10/2017.
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