Common Brand Names: Ancef
Therapeutic Class: A first-generation cephalosporin
Common Injectable Dosage Forms:
Powder for Injection: 250 mg, 500 mg, 1 g, 5 g (bulk), 10 g (bulk), 20 g (bulk) available as bulk
Injection: 500 mg, 1 g, 5 g, 10 g in 20 g vials, 1 g piggybacks
Used in the treatment of respiratory tract, biliary tract, genitourinary tract, skin and skin structure, and bone and joint infections, in septicemia, and in endocarditis due to susceptible organisms: The recommended parenteral dose (IV, IM) is 250 mg to 2 g every 6-12 hours (usually every 8 hours). Severe, life-threatening infections may require up to 12 g/day.
Usual pediatric dosage is 25-100 mg/kg/day divided every 6-8 hours, maximum of 6 g/day.
Administration and Stability:
Cefazolin may be reconstituted in sterile water for injection, bacteriostatic water for injection, or sodium chloride 0.9% for injection. Cefazolin should be reconstituted to a concentration not greater than 330 mg/mL and further diluted with 5-10 mL before direct injection over a period of 3-5 minutes. For intermittent infusion these solutions should be further diluted with 50-100 mL of a compatible solution and infused over 20-60 minutes. IM administration of cefazolin may be given with the solutions at a concentration up to 330 mg/mL. pH 4.5-7
Pharmacology/Pharmacokinetics:
Cefazolin is a first-generation semisynthetic cephalosporin antibiotic which exhibits it bactericidal activity by inhibiting bacterial cell wall synthesis. Cefazolin is effective against S. aureus (including penicillinase-producing strains), S. epidermidis, streptococci, S. pneumoniae. E. coli, P. mirabilis, Klebsiella species, E. aerogenes, and H. influenzae. Cefazolin is not absorbed from the GI tract and must be administered parenterally. The serum half-life is 1.2-2.2 hours in adults with normal renal function. Cefazolin is excreted unchanged in the urine, which means dosage reductions are necessary in the presence of renal impairment.
Drug and Lab Interactions:
Concomitant administration of probenecid may produce increased and prolonged serum levels of cefazolin. Like other cephalosporins, urine glucose determinations using Benedict’s reagent may be false-positive. A false-positive Coombs’ test may occur during cefazolin therapy.
Contraindications/Precautions:
Contraindicated in patients who are hypersensitive to cephalosporins and should be used with caution in patients who have previous history of penicillin allergy. Use with caution when given by IV route due to the possibility of thrombophlebitis. Pain, tenderness, and tissue sloughing may occur with IV extravasation or upon IM injection. Cephalosporins may occasionally cause superinfections. Pregnancy Category B.
Monitoring Parameters:
Renal function, CBC, LFTs, monitor for signs of anaphylaxis.
Adverse Effects:
If hypersensitivity reactions occur, manifested by urticaria, edema laryngospasm, bronchospasm, or hypotension, discontinue use and institute supportive treatment. As with all antibiotics, the possibility of bacterial and fungal overgrowth should be considered. Severe diarrhea may be a sign of pseudomembranous colitis and warrants immediate attention. The most common adverse reactions are nausea, vomiting, and diarrhea, which may be present even with IM/IV use.
Common Clinical Applications:
Effectively used for urinary tract, respiratory tract, skin and skin structure, bone and joint, and biliary tract infections. Also used for gynecologic, cardiac, or gastrointestinal surgical prophylaxis, and for various streptococcal infections caused by susceptible organisms.
