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. |
| Molecular Weight | 454.5 |
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 | Cefazolin crosses the placenta; limited human data show no increased risk of major malformations. Use only if clearly needed. |
| 2nd trimester | No evidence of fetal harm in animal studies; human data limited. Considered safe for use when indicated. |
| 3rd trimester | No known adverse fetal effects; commonly used for surgical prophylaxis during cesarean section. |
Clinical note
Comprehensive clinical and safety monograph for ZEFAZONE IN PLASTIC CONTAINER (ZEFAZONE IN PLASTIC CONTAINER).
| Placental transfer | Cefazolin crosses the placenta. Fetal serum concentrations reach about 30-50% of maternal levels at term. Transfer occurs via passive diffusion. |
| Breastfeeding | Cefazolin is excreted into breast milk in low concentrations (less than 1% of maternal dose). It is considered compatible with breastfeeding; however, observe infant for potential gastrointestinal disturbances or allergic reactions. |
■ FDA Black Box Warning
None.
| Serious Effects |
Hypersensitivity to cefazolin or any cephalosporinSevere immediate hypersensitivity reaction to penicillins (e.g., anaphylaxis)
| 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. |
| Food/Dietary | No significant food interactions. However, alcohol should be avoided due to potential disulfiram-like reaction (cephalosporin side chain). |
| Clinical Pearls |
Loading safety data…
| Lactation Rating | L1 - Compatible |
| 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. |
| 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. |
| Cefazolin is a first-generation cephalosporin with excellent activity against methicillin-sensitive Staphylococcus aureus (MSSA) and Streptococcus spp. It is the preferred agent for surgical prophylaxis due to its favorable pharmacokinetics and safety profile. In renal impairment, dose adjustment is required based on creatinine clearance. Monitor for cross-allergy in patients with penicillin hypersensitivity (approximately 10% risk). |
| Patient Advice | Take exactly as prescribed; complete the full course even if you feel better. · Notify your healthcare provider if you experience rash, itching, or difficulty breathing. · Avoid alcohol during treatment and for 48 hours after the last dose to prevent a disulfiram-like reaction. · Report any severe diarrhea, as this may indicate Clostridioides difficile infection. · This medication is only effective against bacterial infections, not viral infections like the common cold. |