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. |
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 | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for SULFABID (SULFABID).
| Breastfeeding | Small amounts excreted in breast milk (M/P ratio ~0.2); theoretical risk of kernicterus in jaundiced or G6PD-deficient infants; caution advised. Discontinue breastfeeding if infant develops unexplained jaundice or hemolysis. |
| 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. |
■ 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 sulfonamides; porphyria; pregnancy at term; nursing infants <2 months; severe hepatic or renal impairment; concurrent use with methenamine (risk of crystalluria); use in patients with glucose-6-phosphate dehydrogenase deficiency (risk of hemolytic anemia).
| 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. |
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| 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. |