KEFZOL

Clinical safety rating: caution

Comprehensive clinical and safety monograph for KEFZOL (KEFZOL).

How it works

Cephalosporin antibiotic that inhibits bacterial cell wall synthesis by binding to penicillin-binding proteins (PBPs), inhibiting peptidoglycan cross-linking.

What the body does with it

Metabolism	Not significantly metabolized; primarily eliminated unchanged in urine via glomerular filtration and tubular secretion.
Excretion	Renal: 80-90% unchanged via glomerular filtration and tubular secretion. Biliary/fecal: minimal (<5%).
Half-life	1.5-2 hours in adults with normal renal function; prolonged to 20-30 hours in end-stage renal disease (CrCl <10 mL/min).
Protein binding	80-85% bound to serum albumin.
Volume of Distribution	0.12-0.15 L/kg (low, indicating predominantly extracellular distribution; does not penetrate CSF significantly).
Bioavailability	IM: 100% (complete absorption). Oral: not administered orally (poor GI absorption).
Onset of Action	IM: 15-30 minutes; IV: immediate (<5 minutes).
Duration of Action	6-8 hours for susceptible organisms; requires dosing every 6-8 hours for continuous bactericidal effect.

Classification & Brands

Dosing & administration

1-2 g IV/IM every 8 hours for moderate to severe infections; maximum 12 g/day.

Dosage form	INJECTABLE
Renal impairment	CrCl 35-54 mL/min: 1-2 g every 8 hours; CrCl 11-34 mL/min: 1-2 g every 12 hours; CrCl ≤10 mL/min: 1-2 g every 24-48 hours.
Liver impairment	No adjustment required for mild to moderate impairment; use caution in severe hepatic disease (Child-Pugh C) if concurrent renal impairment.
Pediatric use	50-100 mg/kg/day IV/IM divided every 8 hours; up to 100 mg/kg/day for severe infections.
Geriatric use	Consider reduced dosing based on renal function; initial dose adjustment not required if normal renal function; monitor for accumulation.

Use during pregnancy

1st trimester	Consult provider
2nd trimester	Consult provider
3rd trimester	Consult provider

Clinical note

Comprehensive clinical and safety monograph for KEFZOL (KEFZOL).

Breastfeeding	Cefazolin is excreted into breast milk in low concentrations (M/P ratio approximately 0.02-0.07). Considered compatible with breastfeeding; use with caution in nursing infants with hypersensitivity or diarrhea.
Teratogenic Risk	FDA Pregnancy Category B. No evidence of teratogenicity in animal studies. Limited human data; risk cannot be excluded. Avoid use in first trimester unless clearly needed.
Fetal Monitoring

Warnings & precautions

■ FDA Black Box Warning

None.

Side Effect Profile

Serious Effects

Absolute Contraindications

["Hypersensitivity to cefazolin or other cephalosporins","History of severe immediate reaction (e.g., anaphylaxis) to penicillins or other beta-lactam agents"]

Clinical Precautions

Precautions

["Hypersensitivity reactions including anaphylaxis","Clostridioides difficile-associated diarrhea (CDAD)","Risk of bleeding with high doses (due to interference with vitamin K synthesis)","Potential for nephrotoxicity, especially with concurrent aminoglycoside use","Seizures with high doses in renal impairment","Positive direct Coombs test leading to hemolytic anemia"]

Clinical Tips & Counseling

Drug interactions

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KEFZOL

Clinical safety rating: caution

Comprehensive clinical and safety monograph for KEFZOL (KEFZOL).

How it works

Cephalosporin antibiotic that inhibits bacterial cell wall synthesis by binding to penicillin-binding proteins (PBPs), inhibiting peptidoglycan cross-linking.

What the body does with it

Metabolism	Not significantly metabolized; primarily eliminated unchanged in urine via glomerular filtration and tubular secretion.
Excretion	Renal: 80-90% unchanged via glomerular filtration and tubular secretion. Biliary/fecal: minimal (<5%).
Half-life	1.5-2 hours in adults with normal renal function; prolonged to 20-30 hours in end-stage renal disease (CrCl <10 mL/min).
Protein binding	80-85% bound to serum albumin.
Volume of Distribution	0.12-0.15 L/kg (low, indicating predominantly extracellular distribution; does not penetrate CSF significantly).
Bioavailability	IM: 100% (complete absorption). Oral: not administered orally (poor GI absorption).
Onset of Action	IM: 15-30 minutes; IV: immediate (<5 minutes).
Duration of Action	6-8 hours for susceptible organisms; requires dosing every 6-8 hours for continuous bactericidal effect.

Classification & Brands

Dosing & administration

1-2 g IV/IM every 8 hours for moderate to severe infections; maximum 12 g/day.

Dosage form	INJECTABLE
Renal impairment	CrCl 35-54 mL/min: 1-2 g every 8 hours; CrCl 11-34 mL/min: 1-2 g every 12 hours; CrCl ≤10 mL/min: 1-2 g every 24-48 hours.
Liver impairment	No adjustment required for mild to moderate impairment; use caution in severe hepatic disease (Child-Pugh C) if concurrent renal impairment.
Pediatric use	50-100 mg/kg/day IV/IM divided every 8 hours; up to 100 mg/kg/day for severe infections.
Geriatric use	Consider reduced dosing based on renal function; initial dose adjustment not required if normal renal function; monitor for accumulation.

Use during pregnancy

1st trimester	Consult provider
2nd trimester	Consult provider
3rd trimester	Consult provider

Clinical note

Comprehensive clinical and safety monograph for KEFZOL (KEFZOL).

Breastfeeding	Cefazolin is excreted into breast milk in low concentrations (M/P ratio approximately 0.02-0.07). Considered compatible with breastfeeding; use with caution in nursing infants with hypersensitivity or diarrhea.
Teratogenic Risk	FDA Pregnancy Category B. No evidence of teratogenicity in animal studies. Limited human data; risk cannot be excluded. Avoid use in first trimester unless clearly needed.
Fetal Monitoring

Warnings & precautions

■ FDA Black Box Warning

None.

Side Effect Profile

Serious Effects

Absolute Contraindications

["Hypersensitivity to cefazolin or other cephalosporins","History of severe immediate reaction (e.g., anaphylaxis) to penicillins or other beta-lactam agents"]