Sulfadiazine is administered orally.123
Patients should be instructed to drink one full glass (250 mL) of water with each dose of sulfadiazine and at frequent intervals throughout the day while they are receiving the drug.123
The usual adult dosage of sulfadiazine is 2-4 g initially, followed by 2-4 g daily administered in 3-6 equally divided doses.123
When sulfadiazine is used in infants and children older than 2 months of age, the manufacturer recommends 75 mg/kg or 2 g/m2 initially, followed by 150 mg/kg or 4 g/m2 daily administered in 4-6 equally divided doses.123 For the treatment of mild, moderate, or severe infections, the American Academy of Pediatrics (AAP) recommends that children beyond the neonatal period receive a sulfadiazine dosage of 120-150 mg/kg daily given in 4-6 divided doses.292 Pediatric dosage should not exceed 6 g daily.123
Prevention of Rheumatic Fever Recurrence
If sulfadiazine is used as an alternative for prevention of recurrent attacks of rheumatic fever (secondary prophylaxis), the manufacturer recommends that patients older than 2 months of age weighing less than 30 kg receive 500 mg once daily and that those weighing more than 30 kg receive 1 g once daily. 123 The American Heart Association (AHA) and AAP recommend that those weighing 27 kg or less receive a dosage of 500 mg once daily and that those weighing more than 27 kg receive 1 g once daily for such prophylaxis.292,375
When secondary prophylaxis is indicated for prevention of recurrent attacks of rheumatic fever, AHA and AAP recommend long-term, continuous prophylaxis.292,375 (See Table 1.)
Table 1. Recommended Duration of Prophylaxis for Prevention of Rheumatic Fever Recurrence292,375
Patient Category | Duration |
|---|---|
Rheumatic fever without carditis | 5 years or until 21 years of age, whichever is longer |
Rheumatic fever with carditis but no residual heart disease (no valvular disease) | 10 years since last episode or until 21 years of age, whichever is longer |
Rheumatic fever with carditis and residual heart disease (persistent valvular disease) | 10 years since last episode or until 40 years of age, whichever is longer; sometimes for life |
Sulfadiazine should not be used for the treatment of Streptococcus pyogenes (group A β-hemolytic streptococci, GAS) infections (e.g., pharyngitis and tonsillitis) because sulfonamides will not eradicate S. pyogenes and, therefore, will not prevent sequelae such as rheumatic fever and glomerulonephritis.123,292,375,580
For the treatment of nocardiosis, some clinicians recommend that 4-8 g of sulfadiazine be given daily for a minimum of 6 weeks. To prevent relapse, sulfonamide therapy is often continued for many months after apparent cure of nocardiosis.
Sulfadiazine is used in conjunction with pyrimethamine (and leucovorin) or, alternatively, in conjunction with atovaquone for the treatment of toxoplasmosis caused by Toxoplasma gondii .134,155,156 Sulfadiazine in conjunction with pyrimethamine (and leucovorin) is the regimen of choice for initial treatment of toxoplasmosis in adults and adolescents with human immunodeficiency virus (HIV) infection,155 and also is the regimen of choice for treatment of acquired CNS, ocular, or systemic toxoplasmosis in HIV-infected children.156
When a regimen of sulfadiazine and pyrimethamine (and leucovorin) is used for the treatment of T. gondii encephalitis in HIV-infected adults and adolescents, the US Centers for Disease Control and Prevention (CDC), National Institutes of Health (NIH), and HIV Medicine Association of the Infectious Diseases Society of America (IDSA) recommend a sulfadiazine dosage of 1 g every 6 hours in those weighing less than 60 kg or 1.5 g every 6 hours in those weighing 60 kg or more given in conjunction with oral pyrimethamine (200-mg loading dose of pyrimethamine followed by 50 mg once daily in those weighing less than 60 kg or 75 mg once daily in those weighing 60 kg or more) and oral leucovorin (10-25 mg once daily; may be increased to 50 mg once or twice daily).155 Alternatively, HIV-infected adults and adolescents can receive sulfadiazine in a dosage of 1 g every 6 hours in those weighing less than 60 kg or 1.5 g every 6 hours in those weighing 60 kg or more given in conjunction with oral atovaquone (1.5 g twice daily).155 The treatment regimen should be continued for at least 6 weeks;155 a longer duration may be appropriate if clinical or radiologic disease is extensive or there is an incomplete response at 6 weeks.155
For the treatment of acquired CNS, ocular, or systemic toxoplasmosis in HIV-infected children, CDC, NIH, IDSA, and AAP recommend a sulfadiazine dosage of 25-50 mg/kg (up to 1-1.5 g) 4 times daily given in conjunction with oral pyrimethamine (2 mg/kg [up to 50 mg] once daily for 3 days followed by 1 mg/kg [up to 25 mg] once daily) and oral leucovorin (10-25 mg once daily).156 The treatment regimen should be continued for at least 6 weeks;156 a longer duration may be appropriate if the disease is extensive or the response is incomplete at 6 weeks.156
For the treatment of congenital toxoplasmosis, CDC, NIH, IDSA, and AAP recommend a sulfadiazine dosage of 50 mg/kg twice daily given in conjunction with oral pyrimethamine (2 mg/kg once daily for 2 days, followed by 1 mg/kg once daily for 2-6 months and then 1 mg/kg 3 times weekly) and oral or IM leucovorin (10 mg with each pyrimethamine dose).156 The recommended duration of treatment for congenital toxoplasmosis in HIV-infected infants is 12 months.156
Sulfadiazine is used in conjunction with pyrimethamine (and leucovorin) for chronic maintenance therapy (secondary prophylaxis) to prevent relapse of toxoplasmosis† in HIV-infected adults, adolescents, and children who have completed initial treatment of T. gondii encephalitis.155,156 Sulfadiazine in conjunction with pyrimethamine (and leucovorin) is the regimen of choice for secondary prophylaxis of toxoplasmosis in HIV-infected individuals.155,156
For secondary prophylaxis of toxoplasmosis† in HIV-infected adults and adolescents, CDC, NIH, and IDSA recommend a sulfadiazine dosage of 2-4 g daily in 2-4 divided doses given in conjunction with oral pyrimethamine (25-50 mg once daily) and oral leucovorin (10-25 mg once daily).155
CDC, NIH, and IDSA state that secondary prophylaxis against toxoplasmosis generally can be discontinued in HIV-infected adults and adolescents who have successfully completed initial treatment for toxoplasmic encephalitis, remain asymptomatic with respect to toxoplasmic encephalitis, and have CD4+ T-cell counts that have remained greater than 200/mm3 for more than 6 months in response to antiretroviral therapy.155 Secondary prophylaxis should be reinitiated in HIV-infected adults or adolescents if CD4+ T-cell count decreases to less than 200/mm3.155
For secondary prophylaxis of toxoplasmosis† in HIV-infected infants and children, CDC, NIH, IDSA, and AAP recommend a sulfadiazine dosage of 42.5-60 mg/kg twice daily (up to 2-4 g daily) given in conjunction with oral pyrimethamine (1 mg/kg or 15 mg/m2 [up to 25 mg] once daily) and oral leucovorin (5 mg once every 3 days).156
The safety of discontinuing secondary prophylaxis against toxoplasmosis in HIV-infected children receiving antiretroviral therapy has not been extensively studied.156 If a child has completed initial toxoplasmosis treatment, is asymptomatic for toxoplasmosis, and has received at least 6 months of antiretroviral therapy, CDC, NIH, IDSA, and AAP state that consideration can be given to discontinuing secondary prophylaxis in those 1 to less than 6 years of age with CD4+ T-cell percentages that have remained greater than 15% for more than 6 consecutive months or in those 6 years of age or older with CD4+ T-cell counts that have remained greater than 200/mm3 for more than 6 consecutive months.156 Secondary prophylaxis should be reinitiated in HIV-infected children if these parameters are not met.156
For additional information on recommendations regarding treatment and prophylaxis of toxoplasmosis, see Uses: Toxoplasmosis, in Pyrimethamine 8:30.08.