Cefazolin is indicated for the treatment of the following infections caused by susceptible organisms: respiratory tract infections, urinary tract infections, skin and soft tissue infections, biliary tract infections, bone and joint infections, genital infections, septicemia, endocarditis, and for perioperative prophylaxis.

Cefazolin is a first-generation broad-spectrum parenteral cephalosporin antibiotic. It acts by interfering with bacterial cell wall synthesis through inhibition of the transpeptidase enzyme. As a result, the bacterial cell wall becomes weakened, leading to cell swelling and eventual rupture.

Adult Dose

• Moderate to severe infection: 500 mg to 1 gm for every 6 to 8 hours
• Mild infections caused by susceptible Gram-positive cocci: 250 mg to 500 mg for every 8 hours
• Acute uncomplicated urinary tract infections: 1 gm for every 12 hours
• Pneumococcal pneumonia: 500 mg for every 12 hours
• Severe life-threatening infections (e.g. Endocarditis, Septicemia): 1 gm to 1.5 gm for every 6 hours. In rare instances, doses up to 12 gm per day can be used

Perioperative Prophylactic Use: To prevent postoperative infection in contaminated or potentially contaminated surgery, recommended doses are:

• 1 gm IM or IV administered half hour to 1 hour prior to the start of surgery.
• For lengthy operative procedures (e.g. 2 hours or more), 500 mg to 1 gm IM or IV during surgery.
• 500 mg to 1 gm IM or IV every 6 to 8 hours for 24 hours postoperatively.

In surgery where the occurrence of infection may be particularly devastating (e.g. open-heart surgery and prosthetic arthroplasty), the prophylactic administration may be continued for 3 to 5 days following the completion of surgery.

Probenecid may reduce the renal tubular secretion of cephalosporins when used concurrently, resulting in increased and prolonged blood levels of cefazolin.

Cefazolin is contraindicated in patients with known hypersensitivity to the cephalosporin group of antibiotics.

Common side effects of cefazolin include injection site reactions such as pain, swelling, rash, or a hard lump; diarrhea; abdominal pain or cramps; nausea; vomiting; loss of appetite; skin rash or itching; urticaria; white patches or sores inside the mouth or on the lips; vaginal itching or discharge; heartburn; flatulence; rectal itching; confusion; weakness; hypotension; drowsiness; headache; and allergic reactions.

Cefazolin is classified as Pregnancy Category B. It is excreted in very low concentrations in the breast milk of nursing mothers. Therefore, caution should be exercised when cefazolin is administered to a breastfeeding woman.

• As with other cephalosporins, cefazolin should be used cautiously in patients with a history of gastrointestinal disorders, especially colitis.
• Similar to other beta-lactam antibiotics, high doses in patients with impaired renal function may increase the risk of seizures.

Patients with Impaired Renal Function:

• Creatinine clearance 35 to 54 ml/min: 1 unit dose (based on unit doses of 500 mg and 1 gm) every 8 hours
• Creatinine clearance 11 to 34 ml/min: ½ unit dose (based on unit doses of 500 mg and 1 gm) every 12 hours
• Creatinine clearance 10 ml/min: ½ unit dose (based on unit doses of 500 mg and 1 gm) every 18 to 24 hours

Patients with Hepatic Insufficiency: No dosage adjustment is necessary in patients with hepatic insufficiency.

Pediatric Dose: In pediatric patients, a total daily dose of 25 to 50 mg/kg body weight, divided into 3 or 4 equal doses, is effective for most mild to moderate infections. For severe infections, the total daily dose may be increased up to 100 mg/kg body weight. Safety in premature infants and neonates has not been established.

First-generation cephalosporin antibiotic.

After reconstitution, cefazolin remains stable for 24 hours at room temperature or for up to 10 days when stored under refrigeration at 5°C. The color of the reconstituted solution may vary from pale yellow to yellow without any loss of potency.