CEFAZOLIN SODIUM
Clinical safety rating: safe
Probenecid may decrease cephalosporin excretion Nephrotoxicity may occur with concurrent use of potent diuretics.
Cefazolin is a first-generation cephalosporin antibiotic that inhibits bacterial cell wall synthesis by binding to penicillin-binding proteins (PBPs), specifically PBP1a, PBP1b, PBP2a, PBP2b, PBP2x, PBP3, and PBP4, thereby preventing cross-linking of peptidoglycan chains. This leads to cell lysis and death.
| Metabolism | Cefazolin is not significantly metabolized; it undergoes minimal hepatic metabolism. The majority is excreted unchanged in the urine via glomerular filtration and tubular secretion. |
| Excretion | Primarily renal (80-90% unchanged via glomerular filtration and tubular secretion); minimal biliary (1-2%); fecal (<1%) |
| Half-life | Approximately 1.8 hours (range 1.2-2.2 h) in normal renal function; prolonged in renal impairment (up to 30-40 h in ESRD) |
| Protein binding | Approximately 80-85%, primarily to albumin |
| Volume of Distribution | 0.12-0.14 L/kg; low Vd consistent with limited extravascular distribution |
| Bioavailability | IM: approximately 80-100%; IV: 100% |
| Onset of Action | IV: rapid (immediately); IM: 15-30 minutes |
| Duration of Action | Approximately 6-12 hours after IV/IM; dependent on renal function, infection site, and MIC |
1-2 g IV/IM every 8 hours; maximum 12 g/day for severe infections.
| Dosage form | POWDER |
| Renal impairment | CrCl 10-30 mL/min: 0.5-1 g q12h; CrCl <10 mL/min: 0.5-1 g q24-48h; hemodialysis: give after dialysis. |
| Liver impairment | No dose adjustment required for hepatic impairment. |
| Pediatric use | >1 month: 25-50 mg/kg/day IV/IM divided q8h; severe infections up to 100 mg/kg/day divided q6-8h; neonates: 20 mg/kg IV/IM q12h. |
| Geriatric use | Reduce dose based on renal function; CrCl <30 mL/min: 0.5-1 g q12h. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Probenecid may decrease cephalosporin excretion Nephrotoxicity may occur with concurrent use of potent diuretics.
| FDA category | Human |
| Breastfeeding | Cefazolin is excreted into breast milk in low concentrations (M/P ratio approximately 0.02-0.05). Considered compatible with breastfeeding; potential for gastrointestinal disturbance or allergic reaction in infant, but generally considered safe. |
| Teratogenic Risk | FDA Pregnancy Category B. Animal studies have not demonstrated fetal risk, and there are no adequate human studies in pregnant women. No evidence of teratogenicity in first, second, or third trimester. However, use only if clearly needed. |
■ FDA Black Box Warning
No FDA black box warnings.
| Common Effects | Diarrhea |
| Serious Effects |
["Hypersensitivity to cefazolin or other cephalosporins","Prior immediate hypersensitivity reactions to penicillins (cross-sensitivity)"]
| Precautions | ["Hypersensitivity reactions including anaphylaxis","Clostridium difficile-associated diarrhea","Bleeding risk due to interference with vitamin K synthesis","Renal impairment: dose adjustment required","Seizures with high doses or renal failure","Superinfection with prolonged use"] |
| Food/Dietary | No significant food interactions. Alcohol should be avoided during treatment and for 72 hours after last dose due to risk of disulfiram-like reaction. |
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| Fetal Monitoring | Monitor maternal renal function, complete blood count (CBC) with differential, and signs of hypersensitivity. Fetal monitoring not specifically required but general obstetrical surveillance may include growth parameters if long-term use. |
| Fertility Effects | No known effects on fertility. Animal studies have not shown impaired fertility. Cefazolin is not associated with adverse reproductive outcomes. |
| Clinical Pearls | Cefazolin has excellent Gram-positive coverage including MSSA and Streptococci, but not MRSA or Enterococci. It is the preferred agent for surgical prophylaxis due to its short half-life and safety. Adjust dose for renal impairment: CrCl 10-30 mL/min: give q12h; CrCl <10 mL/min: give q24h. In obese patients (BMI >40), consider doubling the standard 2g dose for surgical prophylaxis. Monitor for cross-allergy in penicillin-allergic patients (approximately 1-10% cross-reactivity). Avoid in patients with immediate-type hypersensitivity to penicillin. |
| Patient Advice | Report any signs of allergic reaction like rash, itching, or difficulty breathing immediately. · Take the full course of antibiotics as prescribed even if you feel better. · Cefazolin may cause diarrhea; inform your doctor if it becomes severe or persistent. · If you have kidney problems, your dose may be adjusted; check with your prescriber. · Inform your doctor if you have a history of penicillin allergy before taking cefazolin. · Store cefazolin at room temperature away from moisture and heat. |