SOXAZOLE
Clinical safety rating: caution
Comprehensive clinical and safety monograph for SOXAZOLE (SOXAZOLE).
Soxazole is a synthetic antibacterial agent that inhibits bacterial dihydropteroate synthase, blocking folate synthesis and thereby interfering with nucleic acid production.
| Metabolism | Primarily metabolized by hepatic acetylation and glucuronidation; metabolites excreted renally. |
| Excretion | Renal excretion of unchanged drug (70-80%) and hepatic metabolism with fecal elimination (15-20%); biliary excretion accounts for minor route (<5%). |
| Half-life | Terminal elimination half-life is 8-12 hours in adults; prolonged to 15-20 hours in renal impairment (CrCl <30 mL/min). |
| Protein binding | 92-96% bound to albumin. |
| Volume of Distribution | 0.3-0.5 L/kg, indicating distribution primarily in extracellular fluid. |
| Bioavailability | Oral: 80-90% (well absorbed); IV: 100%. |
| Onset of Action | Oral: 1-2 hours; IV: Immediate (within minutes). |
| Duration of Action | Oral: 8-12 hours; IV: 6-8 hours. Duration is dose-dependent and extended in renal impairment. |
500 mg orally every 6 hours for 7-14 days.
| Dosage form | TABLET |
| Renal impairment | GFR 30-50 mL/min: 250 mg every 6 hours; GFR 10-29 mL/min: 250 mg every 12 hours; GFR <10 mL/min: 250 mg every 24 hours. |
| Liver impairment | Child-Pugh Class A: no adjustment; Child-Pugh Class B: reduce dose by 50%; Child-Pugh Class C: avoid use. |
| Pediatric use | 30 mg/kg/day divided every 6 hours orally; maximum 2 g/day. |
| Geriatric use | Initiate at lower end of dosing range; monitor renal function and adjust accordingly. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for SOXAZOLE (SOXAZOLE).
| Breastfeeding | Excreted into breast milk in low amounts; M/P ratio not established. Considered compatible with breastfeeding; monitor infant for diarrhea, rash, or candidiasis. Caution in infants with glucose-6-phosphate dehydrogenase deficiency due to risk of hemolysis. |
| Teratogenic Risk | First trimester: No evidence of teratogenicity in human studies; animal studies show no fetal harm at therapeutic doses. Second and third trimesters: Risk of decreased amniotic fluid volume due to fetal renal effects; avoid prolonged use near term due to potential premature ductus arteriosus closure. Overall FDA category C. |
■ FDA Black Box Warning
Sulfonamide antibiotics, including soxazole, have been associated with severe adverse reactions such as Stevens-Johnson syndrome, toxic epidermal necrolysis, and agranulocytosis. Fatalities have occurred.
| Serious Effects |
Absolute: Hypersensitivity to soxazole or other sulfonamides, porphyria, severe hepatic or renal impairment. Relative: G6PD deficiency, pregnancy (especially near term), lactation.
| Precautions | Monitor for hypersensitivity reactions, severe cutaneous adverse reactions (SCARs), hemolytic anemia in G6PD-deficient patients, renal and hepatic impairment, and photosensitivity. |
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| Fetal Monitoring | Monitor maternal renal function, hepatic function, and complete blood count periodically. During pregnancy, monitor amniotic fluid volume via ultrasound if used for extended periods. Assess fetal growth and well-being if used in third trimester. |
| Fertility Effects | No evidence of impaired fertility in animal studies. No human data on fertility effects. Theoretical risk of reversible spermatogenesis suppression with high doses; not clinically significant at recommended doses. |