Classifications: antibiotic; first-generation cephalosporin;
Therapeutic: antibiotic
; cephalosporin
Pregnancy Category: B


250 mg, 500 mg, 1 g injection


Semisynthetic, first-generation cephalosporin C with limited activity against gram-negative organisms. Bactericidal action: preferentially binds to one or more of the penicillin-binding proteins (PBP) located on cell walls of susceptible organisms. This inhibits third and final stage of bacterial cell wall synthesis, thus killing the bacterium.

Therapeutic Effect

Effective treatment for bone and joint infections, biliary tract infections, endocarditis prophylaxis and treatment, respiratory tract and genital tract infections, septicemia and skin infections, and surgical prophylaxis.


Severe infections of urinary and biliary tracts, skin, soft tissue, and bone, and for bacteremia and endocarditis caused by susceptible organisms; also perioperative prophylaxis in patients undergoing procedures associated with high risk of infection (e.g., open heart surgery).


Hypersensitivity to any cephalosporin and related antibiotics.

Cautious Use

History of penicillin sensitivity, impaired renal function, patients on sodium restriction; coagulopathy; GI disease, colitis; pregnancy (category B).

Route & Dosage

Moderate to Severe Infections
Adult: IV/IM 250 mg–2 g q8h, up to 2 g q4h (max: 12 g/d)
Child: IV/IM 25–100 mg/kg/d in 3–4 divided doses, up to 100 mg/kg/d (not to exceed adult doses)
Neonate: IV <7 d, 40 mg/kg/d divided q12h; ≥7 d, 40–60 mg/kg/d divided q8–12h

Surgical Prophylaxis
Adult: IV/IM 1–2 g 30–60 min before surgery, then 0.5–1 g q8h
Child: IV/IM 25–50 mg/kg 30–60 min before surgery, then q8h for 24 h

Renal Impairment
Clcr <35 mL/min: dose q12h; 10 mL/min: dose q24h


  • Preparation of IM solution: Reconstitute with sterile water for injection, bacteriostatic water for injection, or 0.9% sodium chloride injection. Reconstituted solutions are stable for 24 hr at room temperature and for 96 hr refrigerated.
  • IM injections should be made deep into large muscle mass. Pain on injection is usually minimal. Rotate injection sites.
  • IV administration to neonates, infants, and children: Verify correct IV concentration and rate of infusion with physician.

PREPARE: Direct: Add 2 mL sterile water for injection to the 500 mg vial to yield 225 mg/mL, or add 2.5 mL to the 1 g vial to yield 330 mg/mL. Shake well to dissolve. Further dilute with 5 mL sterile water for injection.  Intermittent: After initial vial reconstitution, add required dose to 50–100 mL of NS or D5W.  

ADMINISTER: Direct/Intermittent: Infuse 1 g over 5 min or longer as determined by the amount of solution. The risk of IV site reactions may be reduced by proper dilution of IV solution, use of small bore IV needle in a large vein, and by rotating injection sites.  

INCOMPATIBILITIES Solution/additive: aminoglycosides, atracurium, bleomycin, cimetidine, clindamycin, lidocaine, ranitidine. Y-site: Amiodarone, aminoglycosides, amphotericin B cholesteryl complex, cisatracurium, hydromorphone, idarubicin, pentamidine, high dose vancomycin, vinorelbine.

Adverse Effects (≥1%)

Body as a Whole: Anaphylaxis, fever, eosinophilia, superinfections, seizure (high doses in patients with renal insufficiency). GI: Diarrhea, anorexia, abdominal cramps. Skin: Maculopapular rash, urticaria.

Diagnostic Test Interference

Because of cefazolin effect on the direct Coombs' test, transfusion cross-matching procedures and hematologic studies may be complicated. False-positive urine glucose determinations are possible with use of copper sulfate tests (e.g., Clinitest or Benedict's reagent) but not with glucose oxidase tests such as TesTape, Diastix, or Clinistix.


Drug: Probenecid decreases renal elimination of cefazolin.


Peak: 1–2 h after IM; 5 min after IV. Distribution: Poor CNS penetration even with inflamed meninges; high concentrations in bile and in diseased bone; crosses placenta. Elimination: 70% unchanged in urine in 6 h; small amount excreted in breast milk. Half-Life: 90–130 min.

Nursing Implications

Assessment & Drug Effects

  • Determine history of hypersensitivity to cephalosporins, penicillins, and other drugs, before therapy is initiated.
  • Lab tests: Perform culture and sensitivity testing prior to and during therapy. Therapy may be initiated pending results.
  • Monitor I&O rates and pattern: Be alert to changes in BUN, serum creatinine.
  • If patient has had a reaction to penicillin, be alert to signs of hypersensitivity with use of cefazolin. Cross-allergenicity between cephalosporins and penicillin has been reported. Prompt attention should be given to onset of signs of hypersensitivity (see Appendix F).
  • Promptly report the onset of diarrhea, which may or may not be dose related. It is seen especially in patients with history of drug-related GI disturbances. Pseudomembranous colitis, a potentially life-threatening condition, starts with diarrhea.

Patient & Family Education

  • Report promptly any signs or symptoms of superinfection (see Appendix F).
  • Report signs of hemostatic defects: ecchymoses, petechiae, nosebleed.

Common adverse effects in italic, life-threatening effects underlined; generic names in bold; classifications in SMALL CAPS; Canadian drug name; Prototype drug

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