Cefazolin

Indications

Cefazolin is used for: Infections With Gram-Positive Cocci, Mild-to-Moderate Cholecystitis, Uncomplicated Urinary Tract Infection, Prophylaxis against surgical infection, Endocarditis, Community-Acquired Pneumonia

Adult Dose

Parenteral Susceptible infections Adult: Mild: 0.25-0.5 g 8 hrly. Moderate to severe: 0.5-1 g 6-8 hrly. Severe, life-threatening: 1-1.5 g 6 hrly. Max: 12 g daily. All doses to be given by deep IM inj, slow IV inj over 3-5 min, or intermittent or continuous IV infusion. 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

Child Dose

Parenteral Susceptible infections Child: >1 yr 25-50 mg/kg daily in 3 or 4 divided doses to be given by deep IM inj, slow IV inj over 3-5 min, or intermittent or continuous IV infusion. Max: 100 mg/kg daily in divided doses for severe infections. 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

Renal Dose

Renal impairment: CrCl (ml/min) Dosage Recommendation <10 Half the usual dose 18-24 hrly. 11-34 Half the usual dose 12 hrly. 35-54 Usual dose at intervals of at least 8 hr.

Administration

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 IM Administration Inject deep into large muscle mass

Contra Indications

Hypersensitivity to cephalosporins.

Precautions

Patient w/ history of hypersensitivity to penicillins, GI disease particularly colitis, seizure disorder. Renal impairment. Pregnancy and lactation. Monitoring Parameters Monitor prothrombin time; renal, hepatic and haematological function; monitor for signs of anaphylaxis during 1st dose. Lactation: Drug excreted in breast milk; use with caution (American Academy of Pediatrics committee states that drug is compatible with nursing)

Pregnancy-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)

Interactions

May enhance the anticoagulant effect of vit K antagonists (e.g. warfarin). May diminish the therapeutic effect of Na picosulfate, BCG and typhoid vaccine. May decrease the protein binding of fosphenytoin and phenytoin. Probenecid may decrease renal tubular secretion of cefazolin, resulting in increased and prolonged blood levels. May increase the nephrotoxic effects of aminoglycosides.

Adverse Effects

Side effects of Cefazolin : Diarrhoea, oral candidiasis, vomiting, nausea, stomach cramps, anorexia; eosinophilia, itching, drug fever, skin rash, Stevens-Johnson syndrome; neutropenia, leucopenia, thrombocytopenia, thrombocythemia; transient elevation in SGOT, SGPT and alkaline phosphatase levels; hepatitis; increased BUN and creatinine levels, renal failure; phlebitis, induration; genital and anal pruritus (e.g. vulvar pruritus, genital moniliasis, vaginitis). Potentially Fatal: Anaphylaxis, pseudomembranous colitis.

Mechanism of Action

Cefazolin binds to 1 or more of the penicillin-binding proteins (PBPs) which inhibits the final transpeptidation step of peptidoglycan synthesis in bacterial cell wall, thus inhibiting biosynthesis and arresting cell wall assembly resulting in bacterial cell death.