Cephalexin (Keflex®) versus Cefazolin (Kefzol®)
Based on "Antibiotic and Chemotherapy"
written by Roger G. Finch
Difference between Cephalexin and Cefazolin
- Cefazolin is widely used in surgical prophylaxis, especially in biliary tract, because the drug achieves moderately high concentrations in bile.
- Cephalexin is available only in oral dosage forms.
- Cefazolin is available only for parenteral administration.
|• Keflex®||• Kefzol®
|• Cephalosporin antibiotic, first generation|
• Oral suspension
|• Both antibiotics have similar antibacterial coverage, and have good activity against many Gram-positive cocci.
• Cefazolin is more active against Staphylococcus aureus3 , Streptococcus spp.4 and H. influenzae5than cephalexin.
|• Skin and skin structure infections
• Bone and joint infections
• Acute prostatitis
|• Otitis media
• Streptococcal pharyngitis
|• Respiratory tract infections
• Urinary tract infections
• Biliary tract infections
• Perioperative prophylaxis
|• Infective endocarditis (prophylaxis)|
|• Appendicular peritonitis||• Prevention of Group B Streptococcal in newborns (maternal use)1
|Mechanism of action|
• Cephalosporins inhibit the synthesis of bacterial cell walls at the later stages through inactivation of penicillin-binding proteins.
|• 0.5 to 1.2 hours||• 1.8 hours|
|• 90%||• Cefazolin is not appreciably absorbed from gastrointestinal tract.|
|• Cephalexin is minimally metabolized.
• Cephalexin is eliminated in urine (80% to 100% as unchanged drug).
|• Cefazolin is not metabolized in the liver.
• Cefazolin is excreted almost entirely unchanged by the kidneys (about 80% of the drug is eliminated within 24 hours.).
|• Hypersensitivity to any cephalosporin antibiotic|
• Upset stomach
• Abdominal pain
• Allergic reactions
• Allergic reactions
Cephalexin vs Cefazolin for Skin and soft tissue infections
|Results of comparative trial of cefazolin versus cephalexin for the treatment of skin and soft tissue infections6||Cephalexin||Cefazolin|
|Dosage regimen||500 mg 4 times daily for up to 7 days||2 g IV daily plus probenecid 1 g daily for up to 7 days|
|The proportion of patients failing antibiotic treatment at 72 hours||4.2%||6.1%|
|Clinical cure at 7 days||100%||97.7%|
|Cephalexin may provide an effective and non-inferior alternative to parenteral cefazolin in the treatment of uncomplicated skin and soft tissue infection.|
- 1. Apgar BS, Greenberg G, Yen G. Prevention of group B streptococcal disease in the newborn. Am Fam Physician. 2005 Mar 1;71(5):903-10. Available at AAFP
- 2. Wissam Sabbagh. Parotitis: Infectious Disease and Antimicrobial Agents AntiMicrobe
- 3. Hsieh WC, Ho SW. Evaluation of antibacterial activities of cephalosporin antibiotics: cefazolin, cephaloridine, cephalothin, and cephalexin. Zhonghua Min Guo Wei Sheng Wu Xue Za Zhi. 1975 Mar;8(1):1-11.
- 4. Gupta BL, Tahlan A, Dogra V, Rattan A, Bhujwala RA, Shriniwas. Susceptibility of clinical isolates to cephalexin, cefazolin and cefotaxime. Indian Pediatr. 1989 May;26(5):466-71.
- 5. Yourassowsky E, Schoutens E. In vitro bacteriostatic and bactericidal activities of 7 cephalosporin antibiotics on Haemophilus influenzae. Int J Clin Pharmacol Biopharm. 1975 Dec;12(4):433-6.
- 6. Dalen D, Fry A, Campbell SG, Eppler J, Zed PJ. Intravenous cefazolin plus oral probenecid versus oral cephalexin for the treatment of skin and soft tissue infections: a double-blind, non-inferiority, randomised controlled trial. Emerg Med J. 2018 Aug;35(8):492-498.
- 7. Keflex® Prescribing Information PDF
- 8. Ancef® Prescribing Information PDF
Published: August 28, 2018
Last reviewed: August 28, 2018