Congenital toxoplasmosis: Oral: 50 mg/kg/dose every 12 hours for 12 months in combination with pyrimethamine and leucovorin (Ref).
General dosing: Infants ≥2 months, Children, and Adolescents: Oral: 120 to 150 mg/kg/day in divided doses 4 to 6 times daily; maximum daily dose: 6 g/day (Ref).
Toxoplasmosis:
Congenital: Infants: Oral: 50 mg/kg/dose every 12 hours for 12 months in combination with pyrimethamine and leucovorin (Ref).
Acquired (including encephalitis):
Patients with HIV: Note: Use in combination with pyrimethamine and leucovorin for ≥6 weeks, followed by chronic maintenance therapy (secondary prophylaxis); longer duration may be required if incomplete response or extensive disease (Ref).
Infants ≥2 months and Children: Oral: 25 to 50 mg/kg/dose every 6 hours; maximum dose: 1,500 mg/dose (Ref).
Adolescents (Ref):
<60 kg: 1,000 mg every 6 hours.
≥60 kg: 1,500 mg every 6 hours.
Patients without HIV: Infants ≥2 months, Children, and Adolescents: Oral: 25 to 50 mg/kg/dose every 6 hours; maximum dose: 1,500 mg/dose; some clinicians recommend a maximum of 1,000 mg/dose, particularly in patients weighing <60 kg (Ref). Use in combination with pyrimethamine and leucovorin. Treat for 2 to 4 weeks after resolution of illness in immunocompetent patients and ≥4 to 6 weeks after resolution of illness in immunocompromised patients; longer duration may be necessary based on patient response (Ref).
Chorioretinitis : Note: Use in combination with pyrimethamine and leucovorin for ≥6 weeks, followed by chronic maintenance therapy (secondary prophylaxis); longer duration may be required if incomplete response or extensive disease (Ref).
Patients with HIV:
Infants ≥2 months and Children: Oral: 25 to 50 mg/kg/dose every 6 hours; maximum dose: 1,500 mg/dose (Ref).
Adolescents (Ref):
<60 kg: 1,000 mg every 6 hours.
≥60 kg: 1,500 mg every 6 hours.
Patients without HIV: Children and Adolescents: Oral: Loading dose: 75 mg/kg once; followed by 50 mg/kg/dose every 12 hours starting 12 hours after loading dose; maximum daily dose: 4,000 mg/day. Use in combination with pyrimethamine and leucovorin for 1 to 2 weeks after resolution of clinical manifestations; usual duration 4 to 6 weeks; however, prolonged therapy (up to 3 months) may be necessary (Ref).
Chronic maintenance therapy (secondary prevention): Note: Use in combination with pyrimethamine and leucovorin. May consider discontinuation when asymptomatic, the patient has completed ≥6 months of stable antiretroviral therapy with CD4 percentage ≥15% (or CD4 count is >200 cells/mm3 for ages ≥6 years) for >6 consecutive months.
Patients with HIV:
Infants ≥2 months and Children: Oral: 85 to 120 mg/kg/day in 2 to 4 divided doses; maximum daily dose: 4,000 mg/day (Ref).
Adolescents: Oral: 2,000 to 4,000 mg/day in 2 to 4 divided doses (Ref).
There are no dosage adjustments in the manufacturer's labeling.
There are no dosage adjustments in the manufacturer's labeling.
(For additional information see "Sulfadiazine: Drug information")
Usual dosage range: Oral: 2 to 4 g/day in 3 to 6 divided doses.
Toxoplasma gondii encephalitis:
Treatment: Oral: 1 g (≤60 kg) or 1.5 g (>60 kg) every 6 hours in combination with pyrimethamine plus leucovorin calcium (preferred) or alternatively, in combination with atovaquone. Duration is for ≥6 weeks (longer if extensive disease or incomplete response) followed by chronic maintenance therapy (Ref).
Chronic maintenance (secondary prophylaxis): Oral: 2 to 4 g/day in 2 to 4 divided doses in combination with pyrimethamine and leucovorin calcium (preferred) or alternatively, in combination with atovaquone. For patients with HIV, may discontinue if patient remains asymptomatic of signs/symptoms of T. gondii encephalitis, and CD4 count is >200 cells/mm3 for >6 months in response to antiretroviral therapy. For solid organ transplant recipients, chronic maintenance therapy is continued lifelong (Ref).
There are no dosage adjustments provided in the manufacturer's labeling.
There are no dosage adjustments provided in the manufacturer's labeling.
The following adverse drug reactions are derived from product labeling unless otherwise specified.
Postmarketing:
Cardiovascular: Hypersensitivity myocarditis, polyarteritis nodosa
Dermatologic: Erythema multiforme, exfoliative dermatitis, pruritus, skin photosensitivity, skin rash, Stevens-Johnson syndrome (Velter 2018), toxic epidermal necrolysis, urticaria
Endocrine & metabolic: Hypoglycemia (Craft 1977)
Gastrointestinal: Abdominal pain, anorexia, diarrhea, nausea, pancreatitis, stomatitis, vomiting
Genitourinary: Crystalluria (de Sequera 1996), obstructive uropathy (Kabha 2016), toxic nephrosis (with anuria and oliguria) (Craft 1977)
Hematologic & oncologic: Agranulocytosis, aplastic anemia, hemolytic anemia, hypoprothrombinemia, leukopenia, methemoglobinemia, purpuric disease, thrombocytopenia
Hepatic: Hepatic injury (including fulminant hepatitis, hepatitis, hepatorenal syndrome, increased liver enzymes, jaundice) (Khalili 2011)
Hypersensitivity: Drug reaction with eosinophilia and systemic symptoms (Monge-Ortega 2018), hypersensitivity reaction (McLeod 2006), nonimmune anaphylaxis, serum sickness
Nervous system: Ataxia, chills, depression, drug fever, hallucination, headache, insomnia, peripheral neuritis, seizure, vertigo
Neuromuscular & skeletal: Arthralgia, lupus erythematosus (Hogan 2015)
Ophthalmic: Conjunctival injection, injected sclera, periorbital edema
Otic: Tinnitus
Renal: Acute kidney injury (de Sequera 1996), nephrolithiasis (McGettigan 2012), nephrotoxicity (Becker 1996), renal failure syndrome (Marques 1992)
Hypersensitivity to sulfonamides or any component of the formulation; infants <2 months of age unless indicated for the treatment of congenital toxoplasmosis; pregnancy (at term); breastfeeding.
Concerns related to adverse effects:
• Blood dyscrasias: Fatalities associated with severe reactions including agranulocytosis, aplastic anemia and other blood dyscrasias have occurred; discontinue use at first sign of rash or signs of serious adverse reactions.
• Dermatologic reactions: Fatalities associated with severe reactions including Stevens-Johnson syndrome and toxic epidermal necrolysis have occurred; discontinue use at first sign of rash.
• Hepatic necrosis: Fatalities associated with hepatic necrosis have occurred; discontinue use at first sign of rash.
• Sulfonamide (“sulfa”) allergy: Traditionally, concerns for cross-reactivity have extended to all compounds containing the sulfonamide structure (SO2NH2). An expanded understanding of allergic mechanisms indicates cross-reactivity between antibiotic sulfonamides and nonantibiotic sulfonamides may not occur, or at the very least this potential is extremely low (Brackett 2004; Johnson 2005; Slatore 2004; Tornero 2004). In particular, mechanisms of cross-reaction due to antibody production (anaphylaxis) are unlikely to occur with nonantibiotic sulfonamides and antibiotic sulfonamides. A nonantibiotic sulfonamide compound which contains the arylamine structure and therefore may cross-react with antibiotic sulfonamides is sulfasalazine (Zawodniak 2010). T-cell-mediated (type IV) reactions (eg, maculopapular rash) are less understood and it is not possible to completely exclude this potential based on current insights. In cases where prior reactions were severe (Stevens-Johnson syndrome/TEN), some clinicians choose to avoid exposure to these classes.
• Superinfection: Prolonged use may result in fungal or bacterial superinfection, including C. difficile-associated diarrhea (CDAD) and pseudomembranous colitis; CDAD has been observed >2 months postantibiotic treatment.
Disease-related concerns:
• Allergies/asthma: Use with caution in patients with allergies or asthma.
• Glucose 6-phosphate dehydrogenase (G6PD) deficiency: Use with caution in patients with G6PD deficiency; hemolysis may occur.
• Hepatic impairment: Use with caution in patients with hepatic impairment.
• Renal impairment: Use with caution in patients with renal impairment. Maintain adequate hydration to prevent crystalluria.
Special populations:
• Neonates: Sulfa antibiotics have been shown to displace bilirubin from protein binding sites which may potentially lead to hyperbilirubinemia and kernicterus in neonates and young infants; do not use in neonates; avoid use in infants <2 months unless other options are not available.
Dosage form specific issues:
• Benzyl alcohol and derivatives: Some dosage forms may contain sodium benzoate/benzoic acid; benzoic acid (benzoate) is a metabolite of benzyl alcohol; large amounts of benzyl alcohol (≥99 mg/kg/day) have been associated with a potentially fatal toxicity (“gasping syndrome”) in neonates; the “gasping syndrome” consists of metabolic acidosis, respiratory distress, gasping respirations, CNS dysfunction (including convulsions, intracranial hemorrhage), hypotension, and cardiovascular collapse (AAP ["Inactive" 1997]; CDC 1982); some data suggests that benzoate displaces bilirubin from protein binding sites (Ahlfors 2001); avoid or use dosage forms containing benzyl alcohol derivative with caution in neonates. See manufacturer's labeling.
Other warnings/precautions:
• Appropriate use: Not for the treatment of group A beta-hemolytic streptococcal infections.
Excipient information presented when available (limited, particularly for generics); consult specific product labeling.
Tablet, Oral:
Generic: 500 mg
Yes
Tablets (sulfADIAZINE Oral)
500 mg (per each): $20.04
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200 mg/mL Oral Suspension:
A 200 mg/mL oral suspension may be made with sulfadiazine powder and sterile water. Place 50 g sulfadiazine powder in a glass mortar. Add small portions of sterile water and mix to a uniform paste; mix while incrementally adding sterile water to almost 250 mL; transfer to a calibrated bottle, rinse mortar with sterile water, and add sufficient quantity of sterile water to make 250 mL. Label "shake well" and "refrigerate". Stable for 3 days refrigerated. Note: Suspension may also be prepared by crushing one-hundred 500 mg tablets; however, it is stable for only 2 days.
Oral: Administer with at least 8 ounces of water and around-the-clock to promote less variation in peak and trough serum levels.
Oral: Administer with at least 8 ounces of water and around-the-clock to promote less variation in peak and trough serum levels. Oral sodium bicarbonate may be used to alkalinize the urine of patients unable to maintain adequate fluid intake (in order to prevent crystalluria, azotemia, oliguria) (Ref).
Store at controlled room temperature of 20°C to 25°C (68°F to 77°F). Protect from light.
Adjunctive treatment in toxoplasmosis with pyrimethamine (FDA approved in ages ≥2 months and adults [may be used in ages <2 months for treatment of congenital toxoplasmosis]); prophylaxis of rheumatic fever in penicillin-allergic patient (FDA approved in ages ≥2 months and adults).
Although FDA approved for the following indications, sulfadiazine use has been replaced by other agents: Treatment of chancroid, trachoma, inclusion conjunctivitis, urinary tract infections, and nocardiosis (not first line), treatment and prophylaxis of meningococcal meningitis, treatment of Haemophilus influenzae meningitis, adjunctive treatment of uncomplicated attack of malaria due to chloroquine-resistant Plasmodium falciparum (FDA approved in ages ≥2 months and adults).
SulfADIAZINE may be confused with sulfaSALAzine
The Institute for Safe Medication Practices (ISMP) includes this medication among its list of drugs (contraindicated in pregnancy [use at term]) which have a heightened risk of causing significant patient harm when used in error (High-Alert Medications in Community/Ambulatory Care Settings).
KIDs List: Sulfonamides, when used in neonates, are identified on the Key Potentially Inappropriate Drugs in Pediatrics (KIDs) list and should be avoided due to risk of kernicterus except sulfadiazine as adjunctive therapy with pyrimethamine as a treatment of congenital toxoplasmosis (weak recommendation; very low quality of evidence) (PPA [Meyers 2020]).
Substrate of CYP2C9 (Minor), CYP2E1 (Minor), CYP3A4 (Minor); Note: Assignment of Major/Minor substrate status based on clinically relevant drug interaction potential;
Note: Interacting drugs may not be individually listed below if they are part of a group interaction (eg, individual drugs within “CYP3A4 Inducers [Strong]” are NOT listed). For a complete list of drug interactions by individual drug name and detailed management recommendations, use the drug interactions program by clicking on the “Launch drug interactions program” link above.
Note: Interacting drugs may not be individually listed below if they are part of a group interaction (eg, individual drugs within “CYP3A4 Inducers [Strong]” are NOT listed). For a complete list of drug interactions by individual drug name and detailed management recommendations, use the drug interactions program
Ajmaline: Sulfonamides may increase adverse/toxic effects of Ajmaline. Specifically, the risk for cholestasis may be increased. Risk C: Monitor
Aminolevulinic Acid (Systemic): Photosensitizing Agents may increase photosensitizing effects of Aminolevulinic Acid (Systemic). Risk X: Avoid
Aminolevulinic Acid (Topical): Photosensitizing Agents may increase photosensitizing effects of Aminolevulinic Acid (Topical). Risk C: Monitor
Androgens: May increase hypoglycemic effects of Agents with Blood Glucose Lowering Effects. Risk C: Monitor
Antidiabetic Agents: May increase hypoglycemic effects of Hypoglycemia-Associated Agents. Risk C: Monitor
Bacillus clausii: Antibiotics may decrease therapeutic effects of Bacillus clausii. Management: Bacillus clausii should be taken in between antibiotic doses during concomitant therapy. Risk D: Consider Therapy Modification
BCG (Intravesical): Antibiotics may decrease therapeutic effects of BCG (Intravesical). Risk X: Avoid
BCG Vaccine (Immunization): Antibiotics may decrease therapeutic effects of BCG Vaccine (Immunization). Risk C: Monitor
Chloroprocaine (Systemic): May decrease therapeutic effects of Sulfonamide Antibiotics. Management: Avoid concurrent use of chloroprocaine and systemic sulfonamide-based antimicrobials whenever possible. Risk D: Consider Therapy Modification
Cholera Vaccine: Antibiotics may decrease therapeutic effects of Cholera Vaccine. Management: Avoid cholera vaccine in patients receiving systemic antibiotics, and within 14 days following the use of oral or parenteral antibiotics. Risk X: Avoid
CycloSPORINE (Systemic): SulfADIAZINE may decrease serum concentration of CycloSPORINE (Systemic). Risk C: Monitor
Dapsone (Topical): May increase adverse/toxic effects of Methemoglobinemia Associated Agents. Risk C: Monitor
Dexketoprofen: May increase adverse/toxic effects of Sulfonamides. Risk C: Monitor
Fecal Microbiota (Live) (Oral): May decrease therapeutic effects of Antibiotics. Risk X: Avoid
Fecal Microbiota (Live) (Rectal): Antibiotics may decrease therapeutic effects of Fecal Microbiota (Live) (Rectal). Risk X: Avoid
Fosphenytoin-Phenytoin: SulfADIAZINE may increase serum concentration of Fosphenytoin-Phenytoin. Risk C: Monitor
Herbal Products with Glucose Lowering Effects: May increase hypoglycemic effects of Hypoglycemia-Associated Agents. Risk C: Monitor
Hypoglycemia-Associated Agents: May increase hypoglycemic effects of Hypoglycemia-Associated Agents. Risk C: Monitor
Immune Checkpoint Inhibitors (Anti-PD-1, -PD-L1, and -CTLA4 Therapies): Antibiotics may decrease therapeutic effects of Immune Checkpoint Inhibitors (Anti-PD-1, -PD-L1, and -CTLA4 Therapies). Risk C: Monitor
Lactobacillus and Estriol: Antibiotics may decrease therapeutic effects of Lactobacillus and Estriol. Risk C: Monitor
Local Anesthetics: Methemoglobinemia Associated Agents may increase adverse/toxic effects of Local Anesthetics. Specifically, the risk for methemoglobinemia may be increased. Risk C: Monitor
Maitake: May increase hypoglycemic effects of Agents with Blood Glucose Lowering Effects. Risk C: Monitor
Mecamylamine: Sulfonamides may increase adverse/toxic effects of Mecamylamine. Risk X: Avoid
Methenamine: May increase adverse/toxic effects of Sulfonamide Antibiotics. Specifically, the combination may result in the formation of an insoluble precipitate in the urine. Risk X: Avoid
Methotrexate: Sulfonamide Antibiotics may increase adverse/toxic effects of Methotrexate. Management: Consider avoiding concomitant use of methotrexate and therapeutic doses of sulfonamides (eg, trimethoprim/sulfamethoxazole). Patients receiving prophylactic doses of trimethoprim/sulfamethoxazole and methotrexate should be carefully monitored. Risk D: Consider Therapy Modification
Methoxsalen (Systemic): Photosensitizing Agents may increase photosensitizing effects of Methoxsalen (Systemic). Risk C: Monitor
Monoamine Oxidase Inhibitors: May increase hypoglycemic effects of Agents with Blood Glucose Lowering Effects. Risk C: Monitor
Mycophenolate: Antibiotics may decrease active metabolite exposure of Mycophenolate. Specifically, concentrations of mycophenolic acid (MPA) may be reduced. Risk C: Monitor
Nitric Oxide: May increase adverse/toxic effects of Methemoglobinemia Associated Agents. Combinations of these agents may increase the likelihood of significant methemoglobinemia. Risk C: Monitor
Pegvisomant: May increase hypoglycemic effects of Agents with Blood Glucose Lowering Effects. Risk C: Monitor
Porfimer: Photosensitizing Agents may increase photosensitizing effects of Porfimer. Risk X: Avoid
Potassium P-Aminobenzoate: May decrease therapeutic effects of Sulfonamide Antibiotics. Risk X: Avoid
Prilocaine: Methemoglobinemia Associated Agents may increase adverse/toxic effects of Prilocaine. Combinations of these agents may increase the likelihood of significant methemoglobinemia. Management: Monitor for signs of methemoglobinemia when prilocaine is used in combination with other agents associated with development of methemoglobinemia. Avoid use of these agents with prilocaine/lidocaine cream in infants less than 12 months of age. Risk C: Monitor
Primaquine: Methemoglobinemia Associated Agents may increase adverse/toxic effects of Primaquine. Specifically, the risk for methemoglobinemia may be increased. Management: Avoid concomitant use of primaquine and other drugs that are associated with methemoglobinemia when possible. If combined, monitor methemoglobin levels closely. Risk D: Consider Therapy Modification
Procaine: May decrease therapeutic effects of Sulfonamide Antibiotics. Risk X: Avoid
Prothionamide: May increase hypoglycemic effects of Agents with Blood Glucose Lowering Effects. Risk C: Monitor
Pyrimethamine: May increase adverse/toxic effects of Sulfonamide Antibiotics. Risk C: Monitor
Quinolones: May increase hypoglycemic effects of Agents with Blood Glucose Lowering Effects. Quinolones may decrease therapeutic effects of Agents with Blood Glucose Lowering Effects. Specifically, if an agent is being used to treat diabetes, loss of blood sugar control may occur with quinolone use. Risk C: Monitor
Salicylates: May increase hypoglycemic effects of Agents with Blood Glucose Lowering Effects. Risk C: Monitor
Selective Serotonin Reuptake Inhibitor: May increase hypoglycemic effects of Agents with Blood Glucose Lowering Effects. Risk C: Monitor
Sodium Nitrite: Methemoglobinemia Associated Agents may increase adverse/toxic effects of Sodium Nitrite. Combinations of these agents may increase the likelihood of significant methemoglobinemia. Risk C: Monitor
Sodium Picosulfate: Antibiotics may decrease therapeutic effects of Sodium Picosulfate. Management: Consider using an alternative product for bowel cleansing prior to a colonoscopy in patients who have recently used or are concurrently using an antibiotic. Risk D: Consider Therapy Modification
Sulfonylureas: Sulfonamide Antibiotics may increase hypoglycemic effects of Sulfonylureas. Risk C: Monitor
Typhoid Vaccine: Antibiotics may decrease therapeutic effects of Typhoid Vaccine. Only the live attenuated Ty21a strain is affected. Management: Avoid use of live attenuated typhoid vaccine (Ty21a) in patients being treated with systemic antibacterial agents. Postpone vaccination until 3 days after cessation of antibiotics and avoid starting antibiotics within 3 days of last vaccine dose. Risk D: Consider Therapy Modification
Verteporfin: Photosensitizing Agents may increase photosensitizing effects of Verteporfin. Risk C: Monitor
Vitamin K Antagonists: Sulfonamide Antibiotics may increase anticoagulant effects of Vitamin K Antagonists. Management: Consider reducing the vitamin K antagonist dose by 10% to 20% prior to starting the sulfonamide antibiotic. Monitor INR closely to further guide dosing. Risk D: Consider Therapy Modification
Vitamin C or acidifying agents (cranberry juice) may cause crystalluria. Management: Avoid large quantities of vitamin C or acidifying agents (cranberry juice).
Supplemental leucovorin calcium should be administered to reverse symptoms or prevent problems due to folic acid deficiency.
Sulfadiazine crosses the placenta (Speert 1943).
A systematic review of 8 studies (860 pregnancies) and 10 case reports did not find a consistent pattern of adverse fetal or neonatal outcomes following in utero exposure to sulfadiazine. Exposures during the first trimester was limited. Jaundice was reported in some infants; however, data were too limited to calculate a risk of progression to kernicterus in the newborn (Yu 2020).
Due to pregnancy-induced physiologic changes, some pharmacokinetic properties of sulfadiazine may be altered; serum levels may be decreased during pregnancy (Reiter-Owona 2020).
Sulfadiazine is recommended for use in pregnant patients to prevent Toxoplasmosis gondii infection of the fetus, and for the maternal treatment of T. gondii encephalitis (HHS [OI adult 2024]). Sulfadiazine is an alternative agent for the secondary prevention of rheumatic fever in pregnant patients; however, use is not recommended during the third trimester (AHA [Gerber 2009]).
Use with caution in patients with G6PD deficiency; hemolysis may occur. Due to the theoretical increased risk for hyperbilirubinemia and kernicterus, sulfadiazine is contraindicated by the manufacturer for use near term. Neonatal health care providers should be informed if maternal sulfonamide therapy is used near the time of delivery (HHS [OI adult 2024]).
CBC, renal function tests, urinalysis; signs of serious blood disorders (sore throat, fever, pallor, purpura, jaundice); CD4+ count in HIV-exposed/-positive patients treated for toxoplasmosis; observe for change in bowel frequency
Interferes with bacterial growth by inhibiting bacterial folic acid synthesis through competitive antagonism of PABA
Absorption: Well absorbed
Distribution: Throughout body tissues and fluids including pleural, peritoneal, synovial, and ocular fluids; throughout total body water; readily diffused into CSF
Protein binding: 38% to 48%
Metabolism: Via N-acetylation
Half-life elimination: 10 hours
Time to peak: Within 3-6 hours
Excretion: Urine (43% to 60% as unchanged drug, 15% to 40% as metabolites)