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

References

Pharm 101 700

Pharmacology 101

Top 200 drugs

General Surgery Registrar based in Perth, Western Australia. Special interests in rural and Indigenous health.

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