Dosing and uses of Kefzol (cefazolin)
Adult dosage forms and strengths
powder for injection
- 500mg
- 1g
- 2g
- 10g
- 20g
- 100g
- 300g
Moderate-to-Severe Infections
0.5-1 g IV q6-8hr
Mild Infections With Gram-Positive Cocci
250-500 mg IV q8hr
Mild-to-Moderate Cholecystitis
1-2 g IV q8hr for 4-7 days
Uncomplicated Urinary Tract Infection
1 g IV q12hr
Preparation for Surgery
Prophylaxis against infection
Preoperatively: 1-2 g IV/IM ≤60 minutes before procedure (may be repeated in 2-5 hours intraoperatively)
Postoperatively: 0.5-1 g IV q6-8hr for 24 hours
Surgical infection
- Cardiac procedures, hysterectomy, oral or pharyngeal procedures, craniotomy, joint replacement, thoracic procedures, arterial procedures, amputation, traumatic wounds; high-risk esophageal, gastroduodenal, or biliary tract procedures: 1-2 g IV
- Colorectal procedures: 1-2 g IV plus metronidazole 0.5 g IV
- High-risk cesarean section, 2nd trimester abortion: 1 g IV
- Ophthalmic procedures: 100 mg subconjunctivally
Endocarditis
- 1 g IV/IM 30-60 minutes before procedure
- American Heart Association (AHA) guidelines: Endocarditis prophylaxis recommended only for high-risk patients
Bacterial Keratitis (Off-label)
1 drop instilled into affected eye(s) q1-2hr; typically alternated every other hour with antibiotic providing gram-negative coverage (eg, tobramycin)
Extemporaneous compounded fortified cefazolin 50 mg/mL
- Dilute 500 mg parenteral cefazolin powder in sterile water to form 10 mL solution
- Store refrigerated; preparation expires in 7 days
Dosing Modifications
Renal impairment
- CrCl 35-54 mL/min: Give full dose at intervals >8hr
- CrCl 10-35 mL/min: Give therapeutic dose q12hr
- CrCl ≤10 mL/min: Give therapeutic dose q24hr
Hepatic impairment
- Not studied
Dosing Considerations
Susceptible organisms
- Streptococcus pneumoniae, Klebsiella, Haemophilus influenzae, Staphylococcus aureus, group A beta-hemolytic streptococcus, Escherichia coli, Proteus mirabilis, Enterobacter (some strains)
Pediatric dosage forms and strengths
powder for injection
- 500mg
- 1g
- 2g
- 10g
- 20g
- 100g
- 300g
Infections With Gram-Positive Cocci
Neonates (<28 days)
- <7 days: 40 mg/kg/day IV/IM divided q12hr
- >7 days, <2 kg: 40 mg/kg/day IV/IM divided q12hr
- >7 days, >2 kg: 60 mg/kg/day IV/IM divided q8hr
Infants & children
- 25-100 mg/kg/day IV/IM divided q6-8hr; not to exceed 6 g/day
Endocarditis
Prophylaxis
50 mg/kg IV/IM ≤30-60 minutes before procedure; not to exceed 1 g
AHA guidelines: Endocarditis prophylaxis recommended only for high-risk patients
Community-Acquired Pneumonia
>3 months and children: 150 mg/kg/day IV/IM divided q8hr (moderate to severe infections, methicillin susceptible S.Aureus preferred
Dosing Considerations
Cefazolin 2 g for Injection USP and Dextrose Injection USP is not recommended for use in pediatric patients; to avoid unintentional overdose, 1 g cefazolin for Injection USP and dextrose Injection USP should only be used in pediatric patients who require entire contents of 1 g dose and not any fraction of it
There are no dosing recommendations for pediatric patients for perioperative prophylaxis or for pediatric patients with renal impairment
Kefzol (cefazolin) adverse (side) effects
Frequency not defined
Anorexia
Diarrhea
Eosinophilia
Fever
Increased transaminases
Leukopenia
Nausea and vomiting
Neutropenia
Oral candidiasis
Pain at injection site
Phlebitis
Pseudomembranous colitis
Seizure
Stevens-Johnson syndrome
Thrombocytopenia
Thrombocytosis
Transient elevation of hepatic enzymes
Vaginitis
Warnings
Contraindications
Documented hypersensitivity
Cautions
Endocarditis prophylaxis recommended only for high-risk patients, per AHA guidelines
Dose must be adjusted in severe renal insufficiency (high doses may cause CNS toxicity); superinfections and promotion of nonsusceptible organisms may occur with prolonged use or repeated therapy
Prolonged treatment, hepatic or renal disease, or nutritional deficiency may be associated with increased international normalized ratio (INR)
Prolonged use is associated with fungal or bacterial superinfection
Use with caution in patients with seizure disorder (high levels are associated with increased risk of seizures)
Use with caution in renal impairment
Pregnancy and lactation
Pregnancy category: B
Lactation: Drug excreted in breast milk; use with caution (American Academy of Pediatrics committee states that drug is compatible with nursing)
Pregnancy categories
A: Generally acceptable. Controlled studies in pregnant women show no evidence of fetal risk.
B: May be acceptable. Either animal studies show no risk but human studies not available or animal studies showed minor risks and human studies done and showed no risk.
C: Use with caution if benefits outweigh risks. Animal studies show risk and human studies not available or neither animal nor human studies done.
D: Use in LIFE-THREATENING emergencies when no safer drug available. Positive evidence of human fetal risk.
X: Do not use in pregnancy. Risks involved outweigh potential benefits. Safer alternatives exist.
NA: Information not available.
Pharmacology of Kefzol (cefazolin)
Mechanism of action
First-generation semisynthetic cephalosporin that binds to 1 or more penicillin-binding proteins, thereby arresting bacterial cell-wall synthesis and inhibiting bacterial replication; has poor capacity to cross blood-brain barrier; primarily active against skin flora, including S aureus
Absorption
Peak plasma time: 0.5-2 hr (IM); 5 min (IV)
Distribution
Crosses placenta; penetrates CSF poorly
Protein bound: 74-86%
Metabolism
Minimally metabolized in liver
Elimination
Half-life: 90-150 min
Excretion: Urine (80-100% as unchanged drug)
Administration
IV and IM dosing regimens are similar; drug is primarily active against skin flora, including S aureus, and is typically used alone for skin and skin-structure coverage
IV Incompatibilities
Additive: Amikacin, gentamicin
Syringe: Cimetidine, lidocaine
Y-site: Amiodarone(?), amphotericin B
Not specified: Erythromycin, norepinephrine, pentobarbital, tetracycline
IV Compatibilities
Additive: Cimetidine, verapamiL
Y-site: Aminophylline, amiodarone(?), calcium gluconate, lidocaine, vitamins B and C
Not specified: Ampicillin, diazepam, hydrocortisone, potassium chloride
IV Preparation
Reconstitute 500 mg or 1 g with 2 mL or 2.5 mL SWI, respectively, to provide solutions containing approximately 225 or 330 mg/mL
IV push: Further dilute in approximately 5 mL of SWI or according to manufacturer's directions
Infusion: Dilute reconstituted 500 mg or 1 g solution in 50-100 mL NS or D5W
IM Preparation
Reconstitute 500 mg or 1 g with 2 mL or 2.5 mL SWI, respectively, to provide solutions containing approximately 225 or 330 mg/mL
IV Administration
IV push
- Administer directly into vein, and infuse over 3-5 minutes or slowly into tubing of compatible IV infusion solution
- Solution is usually light-yellow to yellow
- Discard if precipitate is present
Infusion: volume control set or piggyback container
- IV infusion stable for 24 hours at room temperature and 96 hours refrigerated
IM Administration
Inject deep into large muscle mass
