Pharm 101: Cephazolin

Class

First generation cephalosporin
Other first generation cephalosporins: cephalexin

Pharmacodynamics

• Beta lactam antibiotic
• Inhibits transpeptidation reaction of bacterial cell wall synthesis
• Halts peptidoglycan synthesis, leading to inhibition of bacterial growth, and ultimately cell death (bacteriocidal)
• Beta-lactam antibiotics kill bacterial cells only when they are actively growing and synthesising cell wall

Pharmacokinetics

• IV administration, every 8 hours
• Penetrates well into most tissues except CNS
• Renal excretion by glomerular filtration and tubular secretion
  • Drugs that block tubular secretion e.g. probenecid, may significantly increase serum levels

Antimicrobial activity

• Very active against Gram positive cocci e.g. strep, staph
• Activity against E Coli, K pneumoniae, Proteus mirabilis and;
• Anaerobic cocci (not Bacteroides fragilis)

Adverse effects of cephalosporins

• Allergy:
  • Cross-allergenicity between penicillins and cephalosporins is ~1%
• Toxicity:
  • Local: Thrombophlebitis after IVI
  • Renal: interstitial nephritis, tubular necrosis (rare)
  • Systemic: rash, drug fever
• Methylthiotetrazole-containing agents (cefotetan, cefoperazone) may cause bleeding disorders and disulfiram-like reactions

Precautions/contraindications

• Penicillin anaphylaxis
• Renal failure

Further reading

• Buttner R. Pharm 101: Cefuroxime. LITFL
• Buttner R. Pharm 101: Ceftriaxone. LITFL
• Buttner R. Pharm 101: Cefepime. LITFL

References

• Katzung BG. Basic and Clinical Pharmacology. 14e. 2018: 802-806, 812