SULFABID
Clinical safety rating: caution
Comprehensive clinical and safety monograph for SULFABID (SULFABID).
Sulfonamide antibiotic that competitively inhibits dihydropteroate synthase, blocking para-aminobenzoic acid (PABA) incorporation into dihydrofolate and thereby inhibiting bacterial folate synthesis.
| Metabolism | Primarily metabolized in the liver via N-acetylation and glucuronidation; undergoes enterohepatic recirculation. Metabolites are excreted renally. |
| Excretion | Renal: 80-90% unchanged via glomerular filtration and tubular secretion. Biliary: 5-10% as metabolites. Fecal: <5%. |
| Half-life | Terminal elimination half-life: 8-12 hours in adults with normal renal function; prolonged to 20-50 hours in renal impairment (CrCl <30 mL/min), requiring dose adjustment. |
| Protein binding | 50-70% bound primarily to albumin. |
| Volume of Distribution | 0.2-0.4 L/kg, indicating distribution primarily in extracellular fluid and limited tissue penetration (except for urine). |
| Bioavailability | Oral: 85-95% (well absorbed). Intravenous: 100%. |
| Onset of Action | Oral: 30-60 minutes to therapeutic plasma levels. Intravenous: immediate onset (within minutes). |
| Duration of Action | Oral: 12-24 hours. Duration extended in renal impairment due to accumulation. |
| Molecular Weight | 250.28 |
500 mg orally every 12 hours for 10-14 days.
| Dosage form | SUSPENSION |
| Renal impairment | CrCl >50 mL/min: no adjustment; CrCl 10-50 mL/min: 500 mg every 24 hours; CrCl <10 mL/min: 500 mg every 48-72 hours. |
| Liver impairment | No specific guidelines; use with caution in severe hepatic impairment (Child-Pugh Class C) and monitor for adverse effects. |
| Pediatric use | 10-15 mg/kg/day divided every 12 hours, not to exceed adult dose. |
| Geriatric use | Start at lower end of dosing range if renal function is impaired; monitor renal function and adjust dose accordingly. |
| 1st trimester | Avoid due to potential teratogenic effects; sulfonamides may cause kernicterus in neonates if used near term. |
| 2nd trimester | Use only if clearly needed; consider alternative agents with better safety profiles. |
| 3rd trimester | Contraindicated in third trimester due to risk of kernicterus and neonatal jaundice. |
Clinical note
Comprehensive clinical and safety monograph for SULFABID (SULFABID).
| Placental transfer | Crosses placenta readily; achieves fetal plasma concentrations 50-80% of maternal levels. |
| Breastfeeding | Sulfabid is excreted into breast milk in low concentrations but may theoretically cause kernicterus in nursing infants, especially those with G6PD deficiency; use with caution. |
| Lactation Rating |
■ FDA Black Box Warning
Sulfonamides have been associated with severe hypersensitivity reactions including Stevens-Johnson syndrome, toxic epidermal necrolysis, agranulocytosis, aplastic anemia, and other blood dyscrasias. Use is contraindicated in patients with prior hypersensitivity to sulfonamides.
| Serious Effects |
Hypersensitivity to sulfonamidesPorphyriaSevere hepatic impairmentThird trimester of pregnancyInfants <2 months of age (unless congenital toxoplasmosis)
| Precautions | Risk of hypersensitivity reactions including Stevens-Johnson syndrome; photosensitivity; hematological toxicity (agranulocytosis, aplastic anemia); renal toxicity (crystalluria, oliguria, anuria); hepatic toxicity; caution in impaired hepatic or renal function; avoid in pregnancy near term and nursing mothers due to risk of kernicterus in neonates. |
| Food/Dietary | No significant food interactions. However, avoid alcohol as it may increase risk of adverse effects. Take on an empty stomach (1 hour before or 2 hours after meals) for optimal absorption. Maintain adequate hydration (2-3 liters daily) to prevent crystalluria. |
Loading safety data…
| L3 - Moderately Safe |
| Teratogenic Risk | First trimester: crosses placenta; known risk of kernicterus in newborn when used near term; avoid due to potential for bilirubin displacement and neurotoxicity. Second and third trimesters: potential for neonatal jaundice and hemolytic anemia in G6PD-deficient infants; contraindicated after 38 weeks gestation. |
| Fetal Monitoring | Liver function tests (LFTs), renal function, complete blood count (CBC) with differential, bilirubin levels in neonate. Monitor for signs of hemolytic anemia or hyperbilirubinemia. |
| Fertility Effects | No known clinically significant effects on human fertility. |
| Clinical Pearls | SULFABID (sulfadiazine) is a short-acting sulfonamide. Monitor for crystalluria; ensure adequate hydration and urinary output. Avoid in patients with G6PD deficiency due to risk of hemolytic anemia. Contraindicated in pregnancy (near term) and lactation due to kernicterus risk. Use with caution in renal impairment; adjust dose based on creatinine clearance. |
| Patient Advice | Take this medication with a full glass of water to prevent kidney stones. · Drink plenty of fluids throughout the day to maintain good urine output. · Avoid prolonged exposure to sunlight and use sunscreen to prevent photosensitivity reactions. · Complete the full course of therapy even if you feel better to prevent resistance. · Notify your doctor immediately if you develop skin rash, fever, sore throat, or unusual bleeding. |