Cefazolin

Pronunciation: sef-AH-zoe-lin
Class: Antibiotic, Cephalosporin

Trade Names

Cefazolin
- Powder for injection 500 mg
- Powder for injection 1 g
- Powder for injection 10 g
- Powder for injection 20 g

Pharmacology

Inhibition of bacterial cell wall synthesis.

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Pharmacokinetics

Absorption

Following a 500 mg dose, mean serum concentrations are 37 and 3 mcg/mL at 1 and 8 h, respectively. After a 1 g dose, mean serum levels are 64 and 7 mcg/mL at 1 and 8 h, respectively.

Distribution

Bile concentrations can exceed serum levels by up to 5 times. Promptly crosses the placenta.

Metabolism

Not metabolized.

Elimination

IM t _½ approximately 2 h and IV t _½ approximately 1.8 h. Excreted unchanged in urine. Approximately 60% excreted in urine in 6 h and 70% to 80% within 24 h. Peak urine concentrations after IM doses of 500 mg and 1 g are approximately 2,400 and 4,000 mcg/mL, respectively.

Indications and Usage

Treatment of infections of respiratory tract, urinary tract, skin and skin structures, biliary tract, and bone and joint; treatment of genital infections; treatment of septicemia; treatment of endocarditis caused by susceptible strains of specific microorganisms; perioperative prophylaxis.

Contraindications

Hypersensitivity to cephalosporins.

Dosage and Administration

IM/IV Moderate to severe infections: 500 mg to 1 g every 6 to 8 h. Mild infections: 250 to 500 mg every 8 h. Severe, life-threatening infections: 1 to 1.5 g every 6 h.

IM/IV Mild to moderate infections: 25 to 50 mg/kg (10 to 20 mg/lb) daily divided into 3 or 4 equal doses. Severe infections: 100 mg/kg (45 mg/lb).

IM/IV 1 g every 12 h.

IM/IV 500 mg every 12 h.

IM/IV 1 g administered ½ to 1 h prior to start of surgery. Operative procedures of 2 h or more: 500 mg to 1 g during surgery. Postoperatively: 500 mg to 1 g every 6 to 8 h for 24 h.

IM/IV Ccr 55 mL/min or greater: Administer full dose. Ccr 35 to 54 mL/min: Administer full dose restricted to at least 8 h intervals. Ccr 11 to 34 mL/min: Administer 50% of usual dose every 12 h. Ccr 10 mL/min or less: Administer 50% of usual dose every 18 to 24 h.

IM/IV Dosage recommendations apply after an initial loading dose. Ccr 70 to 40 mL/min: Administer 60% of normal daily dose in equally divided doses every 12 h. Ccr 40 to 20 mL/min: Administer 25% of normal daily dose in equally divided doses every 12 h. Ccr 20 to 5 mL/min: Administer 10% of normal daily dose every 24 h.

General Advice

• Shake well when reconstituted.
• Inspect visually for particulate matter prior to administration; discard if particulate matter is evident.
• Reconstituted solution may be pale yellow to yellow without a change in potency.

Storage/Stability

Before reconstitution, store at 68° to 77°F. Protect from light. When reconstituted or diluted, stable for 24 h at room temperature or 10 days under refrigeration at 41°F.

Drug Interactions

Increased risk of nephrotoxicity.

Cefazolin renal tubular secretion may be decreased, increasing and prolonging blood levels.

Anticoagulant effect may be increased.

Laboratory Test Interactions

False-positive direct Coombs test results may occur; false-positive reaction to glucose in the urine may occur with Benedict solution, Fehling solution, or Clinitest tablets but not with enzyme-based tests (eg, Clinistix ).

Adverse Reactions

CNS

Hyperactivity; hypertonia.

GI

Abdominal pain; anal pruritus; anorexia; colitis; diarrhea; nausea; oral candidiasis; pseudomembranous colitis; stomach cramps; vomiting.

Genitourinary

Genital pruritus (including genital moniliasis, vaginitis, vulvar pruritus).

Hepatic

Cholestasis.

Hematologic-Lymphatic

Agranulocytosis; aplastic anemia; hemolytic anemia; hemorrhage; leukopenia; neutropenia; pancytopenia; thrombocythemia; thrombocytopenia.

Lab Tests

Increased alkaline phosphatase, AST, or ALT; elevated bilirubin; elevated LDH; increased creatine; prolonged prothrombin time.

Local

Pain; phlebitis.

Renal

Increased BUN and creatinine; renal function impairment; toxic nephropathy.

Miscellaneous

Allergy (including anaphylaxis, drug fever, eosinophilia, erythema multiforme, itching, skin rash, serum sickness–like reactions, Stevens-Johnson syndrome, toxic epidermal necrolysis, urticaria); superinfection.

Precautions

Pregnancy

Category B .

Lactation

Excreted in breast milk.

Children

Safety and efficacy not established in children 1 month of age or younger.

Renal Function

Dosage adjustment may be needed.

Superinfection

May result in bacterial or fungal overgrowth of nonsusceptible microorganisms.

GI disease

Use with caution, especially in patients with history of colitis.

Prothrombin activity

May be decreased.

Pseudomembranous colitis

Consider in patients who develop diarrhea.

Patient Information

• Advise patient to report nausea, vomiting, diarrhea, skin rash, hives, and muscle or joint pain to health care provider.
• Advise patient to maintain normal fluid intake while receiving this medication.
• Instruct patient to report signs of superinfection: black, furry tongue; white patches in mouth; foul-smelling stools; vaginal itching or discharge.
• Instruct patient to immediately seek emergency care if wheezing or difficulty breathing occurs.

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