ZEFAZONE IN PLASTIC CONTAINER
Clinical safety rating: caution
Comprehensive clinical and safety monograph for ZEFAZONE IN PLASTIC CONTAINER (ZEFAZONE IN PLASTIC CONTAINER).
Cephalosporin antibiotic; inhibits bacterial cell wall synthesis by binding to penicillin-binding proteins (PBPs), disrupting peptidoglycan cross-linking.
| Metabolism | Cefazolin is primarily excreted unchanged by the kidneys via glomerular filtration and tubular secretion. Minimal hepatic metabolism occurs via acetylation. |
| Excretion | Primarily renal, 70-80% excreted unchanged in urine via glomerular filtration and tubular secretion; 20-30% biliary excretion with fecal elimination. |
| Half-life | Terminal elimination half-life ~1.5 hours in normal renal function; prolonged in renal impairment (up to 20-30 hours in anuria). |
| Protein binding | ~35-45% bound, primarily to albumin. |
| Volume of Distribution | Vd ~0.2-0.3 L/kg, indicating distribution mainly in extracellular fluid. |
| Bioavailability | Intravenous: 100%; intramuscular: ~90-95%. |
| Onset of Action | Intravenous: immediate (minutes); intramuscular: 15-30 minutes. |
| Duration of Action | Intravenous: 6-8 hours; intramuscular: 6-8 hours; sustained release forms may extend to 12 hours. |
1 to 2 g intravenously every 6 to 8 hours depending on infection severity.
| Dosage form | INJECTABLE |
| Renal impairment | CrCl 30-50 mL/min: 1-2 g every 8-12 hours; CrCl 10-29 mL/min: 1-2 g every 12-24 hours; CrCl <10 mL/min: 1-2 g every 24-48 hours. |
| Liver impairment | No significant dose adjustment required for mild to moderate hepatic impairment; use with caution in severe impairment. |
| Pediatric use | 50-150 mg/kg/day intravenously divided every 6-8 hours, maximum 6 g/day. |
| Geriatric use | Dose based on renal function; start at lower end of dosing range and monitor renal function closely. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for ZEFAZONE IN PLASTIC CONTAINER (ZEFAZONE IN PLASTIC CONTAINER).
| Breastfeeding | Excreted in human milk in low amounts. M/P ratio unknown. Use caution due to potential for alteration of infant gut flora and allergic sensitization. American Academy of Pediatrics considers compatible with breastfeeding. |
| Teratogenic Risk | FDA Pregnancy Category B. First trimester: Animal studies show no fetal harm, but no adequate human studies. Second and third trimesters: No evidence of teratogenicity; however, kernicterus risk in neonates if maternal bilirubin displacement occurs. |
■ FDA Black Box Warning
None.
| Serious Effects |
Hypersensitivity to cephalosporins or any component of the formulation; history of severe immediate hypersensitivity reaction (e.g., anaphylaxis) to penicillins or other beta-lactams.
| Precautions | Hypersensitivity reactions including anaphylaxis; Clostridioides difficile-associated diarrhea; risk of bleeding due to hypoprothrombinemia; superinfection; renal impairment requiring dose adjustment; false-positive Coombs test. |
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| Fetal Monitoring |
| Monitor maternal renal function, hepatic function, and complete blood count periodically. Fetal monitoring not routinely required; assess for neonatal jaundice if administered near term. |
| Fertility Effects | No known adverse effects on fertility in animal studies. No human data available. |