MEFOXIN
Clinical safety rating: caution
Comprehensive clinical and safety monograph for MEFOXIN (MEFOXIN).
Cefoxitin is a cephamycin antibiotic that inhibits bacterial cell wall synthesis by binding to penicillin-binding proteins (PBPs), thereby inhibiting peptidoglycan cross-linking.
| Metabolism | Primarily hepatic metabolism; minimal metabolism via deacetylation. |
| Excretion | Primarily renal (85% unchanged) via glomerular filtration and tubular secretion; small biliary/fecal (<5%) |
| Half-life | Terminal elimination half-life 0.7-1.1 hours in normal renal function; prolonged to 5-9 hours in severe renal impairment (CrCl <10 mL/min) |
| Protein binding | 65-80% bound to serum albumin |
| Volume of Distribution | 0.12-0.15 L/kg; approximates extracellular fluid volume |
| Bioavailability | IM: ~85% |
| Onset of Action | Intravenous: immediate; intramuscular: 15-30 minutes |
| Duration of Action | 6-8 hours for susceptible organisms; prolonged in renal impairment |
1-2 g IV every 6-8 hours; usual dose 1 g IV every 6 hours for uncomplicated infections, 2 g IV every 6-8 hours for severe infections. Maximum 12 g/day.
| Dosage form | INJECTABLE |
| Renal impairment | CrCl 30-50 mL/min: 1-2 g every 8 hours. CrCl 10-29 mL/min: 1-2 g every 12 hours. CrCl <10 mL/min: 1-2 g every 24-48 hours. For continuous ambulatory peritoneal dialysis (CAPD): 1 g every 24 hours. For hemodialysis: 1-2 g after each dialysis session. |
| Liver impairment | No specific Child-Pugh based modifications available; caution in severe hepatic impairment due to potential toxicity, but no standard dose adjustment recommended. |
| Pediatric use | Infants and children >3 months: 80-160 mg/kg/day IV divided every 6-8 hours. Maximum 12 g/day. Neonates: weight-based dosing per gestational age: <2 weeks: 100 mg/kg/day IV divided every 12 hours; >2 weeks: 100-150 mg/kg/day IV divided every 8-12 hours. |
| Geriatric use | No specific dose adjustment based solely on age; use weight and renal function to determine dose. Monitor renal function closely. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for MEFOXIN (MEFOXIN).
| Breastfeeding | Cefoxitin is excreted into breast milk in low concentrations (M/P ratio not established). Considered compatible with breastfeeding; monitor for infant GI disturbances. |
| Teratogenic Risk | FDA Pregnancy Category B. No evidence of teratogenicity in animal studies; insufficient human data. Use only if clearly needed. |
| Fetal Monitoring | No specific fetal monitoring required. Observe for maternal adverse effects (hypersensitivity, diarrhea). |
■ FDA Black Box Warning
No FDA black box warning.
| Serious Effects |
["Hypersensitivity to cefoxitin or other cephalosporins","Known hypersensitivity to carbapenems"]
| Precautions | ["Hypersensitivity reactions including anaphylaxis","Clostridioides difficile-associated diarrhea (CDAD)","Seizures at high doses in patients with renal impairment","Prolonged bleeding time","Overgrowth of non-susceptible organisms"] |
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| Fertility Effects | No known adverse effects on human fertility. |