SULFAIR-15
Clinical safety rating: caution
Comprehensive clinical and safety monograph for SULFAIR-15 (SULFAIR-15).
Sulfadoxine is a long-acting sulfonamide that inhibits dihydropteroate synthase, blocking folate synthesis. Pyrimethamine inhibits dihydrofolate reductase, synergistically inhibiting nucleic acid synthesis in Plasmodium species.
| Metabolism | Sulfadoxine is metabolized via acetylation and glucuronidation in the liver. Pyrimethamine is metabolized in the liver by CYP2C9 and other pathways. |
| Excretion | Renal excretion unchanged: 70%; hepatic metabolism to inactive metabolites: 20%; fecal excretion: 10%. |
| Half-life | 12–15 hours in healthy adults; prolonged to 20–30 hours in moderate hepatic impairment. |
| Protein binding | 98% bound to albumin. |
| Volume of Distribution | 0.15 L/kg, indicating limited extravascular distribution. |
| Bioavailability | Oral: 85%; intramuscular: 100%. |
| Onset of Action | Oral: 30–60 minutes; IV: 5–10 minutes. |
| Duration of Action | 8–12 hours following single oral dose; 12–18 hours after multiple doses due to accumulation. |
| Molecular Weight | 250.3 |
15 mg orally every 6 hours, not to exceed 60 mg/day.
| Dosage form | SOLUTION/DROPS |
| Renal impairment | GFR ≥ 60 mL/min: no adjustment; GFR 30-59: 15 mg every 8 hours; GFR 15-29: 15 mg every 12 hours; GFR <15: avoid use. |
| Liver impairment | Child-Pugh A: no adjustment; Child-Pugh B: reduce dose by 50%; Child-Pugh C: contraindicated. |
| Pediatric use | 0.5 mg/kg orally every 6 hours, maximum 60 mg/day; not recommended under 1 year. |
| Geriatric use | Initial dose 7.5 mg every 6 hours; titrate to response; monitor renal function. |
| 1st trimester | Limited human data; animal studies show risk. Use only if benefit outweighs risk. May be associated with teratogenic effects. |
| 2nd trimester | Caution advised. Monitor maternal renal function and electrolytes. Potential for fetal electrolyte disturbances. |
| 3rd trimester | Avoid near term due to risk of neonatal hypoglycemia, hyperbilirubinemia, and kernicterus. |
Clinical note
Comprehensive clinical and safety monograph for SULFAIR-15 (SULFAIR-15).
| Placental transfer | Crosses placenta readily; fetal serum levels reach 50-90% of maternal levels. |
| Breastfeeding | Excreted into breast milk; potential for kernicterus in nursing infants. Contraindicated in breastfeeding for premature infants or those with hyperbilirubinemia. |
| Lactation Rating |
■ FDA Black Box Warning
Fatal hypersensitivity reactions, including Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN), have been reported. Contraindicated in patients with a history of sulfonamide hypersensitivity.
| Serious Effects |
Hypersensitivity to sulfonamidesPorphyriaSevere hepatic or renal impairmentPregnancy at term or breastfeeding (risk of kernicterus)Infants <2 months of age
| Precautions | Risk of severe cutaneous adverse reactions (SJS/TEN); bone marrow suppression (especially with prolonged use); folate deficiency; hypersensitivity reactions; hematologic monitoring recommended. |
| Food/Dietary | Avoid alcohol; may cause disulfiram-like reaction (flushing, headache, nausea). Maintain consistent carbohydrate intake to prevent hypoglycemia. Grapefruit juice may alter drug metabolism; limit or avoid consumption. High-fiber foods can delay absorption; take medication with a meal. |
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| L4 (Possibly Hazardous) |
| Teratogenic Risk | First trimester: Sulfamethoxazole/trimethoprim (SMX/TMP) is associated with increased risk of neural tube defects, cardiovascular malformations, and oral clefts. Second/third trimester: Risk of kernicterus due to bilirubin displacement; avoid near term. |
| Fetal Monitoring | Monitor maternal CBC (especially platelets and WBC), renal function, and liver enzymes. Fetal ultrasound for anomalies if exposed in first trimester. Monitor for neonatal hyperbilirubinemia and kernicterus if administered near delivery. |
| Fertility Effects | SMX/TMP may impair folate metabolism, potentially reducing fertility due to antifolate effects. In males, may cause reversible oligospermia. Discontinuation typically restores normal fertility. |
| Clinical Pearls | Sulfair-15 is a sulfonylurea antidiabetic agent with a rapid onset of action; monitor for hypoglycemia, especially in elderly patients or those with renal impairment. Avoid use in G6PD deficiency as it may precipitate hemolytic anemia. Titrate dose slowly to minimize risk of hypoglycemia. Consider dose adjustment when used with other hypoglycemic agents or drugs that affect hepatic metabolism. |
| Patient Advice | Take this medication exactly as prescribed, typically once daily with breakfast to reduce gastrointestinal upset. · Monitor blood glucose regularly and recognize symptoms of hypoglycemia (sweating, shakiness, hunger, confusion). · Do not skip meals, and maintain a consistent carbohydrate intake to prevent blood sugar fluctuations. · Avoid alcohol consumption as it can increase the risk of hypoglycemia. · Inform your healthcare provider if you develop rash, jaundice, or signs of infection (fever, sore throat). |