SEFFIN
Clinical safety rating: caution
Comprehensive clinical and safety monograph for SEFFIN (SEFFIN).
SEFFIN is a brand name for cefazolin, a first-generation cephalosporin antibiotic. It inhibits bacterial cell wall synthesis by binding to penicillin-binding proteins (PBPs), leading to cell lysis and death. It is bactericidal against susceptible organisms.
| Metabolism | Cefazolin undergoes minimal hepatic metabolism; it is primarily excreted unchanged in the urine via glomerular filtration and tubular secretion. It is not metabolized by cytochrome P450 enzymes. |
| Excretion | Primarily renal (80-90% unchanged) via glomerular filtration and tubular secretion; minor biliary excretion (<5%) and fecal elimination. |
| Half-life | Terminal elimination half-life is approximately 0.5-1 hour in adults with normal renal function; prolonged to 20-40 hours in severe renal impairment (CrCl <10 mL/min). |
| Protein binding | Approximately 10% bound to serum proteins (mainly albumin). |
| Volume of Distribution | 0.13-0.2 L/kg, indicating limited distribution primarily to extracellular fluid. |
| Bioavailability | Intravenous: 100%; intramuscular: 100%; oral: negligible (<1%) due to instability in gastric acid. |
| Onset of Action | Intravenous: immediate; intramuscular: within 1-2 hours; oral: not applicable due to poor oral bioavailability. |
| Duration of Action | 6-8 hours for most indications; dosing interval typically 4-6 hours due to short half-life. |
1-2 g IV/IM every 6-8 hours; maximum 8 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 hours. Hemodialysis: dose after dialysis. |
| Liver impairment | No dose adjustment required for mild-moderate impairment; severe impairment (Child-Pugh C): consider dose reduction or interval prolongation, monitor closely. |
| Pediatric use | Infants and children: 50-100 mg/kg/day IV/IM divided every 6-8 hours; neonates: 25-50 mg/kg/day every 8-12 hours. Do not exceed adult dose. |
| Geriatric use | Adjust dose based on renal function; use lower end of dosing range (e.g., 1 g every 8-12 hours). Monitor for neurotoxicity (seizures). |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for SEFFIN (SEFFIN).
| Breastfeeding | SEFFIN is excreted into breast milk in low concentrations (M/P ratio approximately 0.01-0.03). It is considered compatible with breastfeeding; however, potential disruption of infant gut flora and rare hypersensitivity reactions should be considered. The benefits of breastfeeding outweigh the minimal risks. |
| Teratogenic Risk | SEFFIN (cefalexin, a first-generation cephalosporin) is classified as FDA Pregnancy Category B. There is no evidence of teratogenicity in animal studies. In humans, data do not indicate an increased risk of major congenital malformations. Use in the first trimester is generally considered safe; however, it should be used only when clearly needed. In the second and third trimesters, no known fetal risks have been reported. |
■ FDA Black Box Warning
No FDA black box warning has been issued for cefazolin. However, note that cephalosporins are contraindicated in patients with immediate-type hypersensitivity reactions to penicillins; use with caution due to potential cross-allergenicity.
| Serious Effects |
Hypersensitivity to cefazolin or any cephalosporin, serious immediate hypersensitivity reaction to penicillins (e.g., anaphylaxis), porphyria (relative contraindication).
| Precautions | Hypersensitivity reactions (including anaphylaxis), Clostridium difficile-associated diarrhea, dose adjustment in renal impairment, superinfection, increased risk of bleeding with high doses, prolonged use may cause bacterial overgrowth. |
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| Fetal Monitoring | Monitor maternal renal function and signs of hypersensitivity. In neonates, monitor for diarrhea, rash, and candidiasis. No specific fetal monitoring required. |
| Fertility Effects | No known effects on fertility. Cefalexin has not been associated with impaired fertility in animal studies or human reports. |