Paper II
2017 February (2010 Scheme) · 40 marks · 120 min

Question

Classify cephalosporins. Mention the mechanism of action, adverse effects and uses of third generation cephalosporin. (2+2+2=6)

Q26 marksEssays

Answer

Classification of cephalosporins

  • First generation: Cefazolin, Cephalexin
  • Second generation: Cefuroxime, Cefaclor
  • Third generation: Ceftriaxone, Cefotaxime, Ceftazidime
  • Fourth generation: Cefepime
  • Fifth generation: Ceftaroline

Mechanism of action (third generation, e.g., Ceftriaxone)

  • Binds to penicillin-binding proteins (PBPs), inhibiting bacterial cell wall transpeptidation (peptidoglycan cross-linking) — bactericidal, mainly against actively dividing bacteria

Adverse effects

  • Hypersensitivity reactions (cross-reactivity with penicillin allergy in some patients)
  • GI upset, diarrhoea
  • Biliary sludging (ceftriaxone, at high doses/prolonged use)
  • Nephrotoxicity (less than aminoglycosides)
  • Disulfiram-like reaction with alcohol (some agents)

Uses

  • Meningitis (good CSF penetration)
  • Gonorrhoea (ceftriaxone, single-dose IM)
  • Typhoid fever
  • Community-acquired pneumonia, complicated UTIs
  • Broad Gram-negative and good Gram-positive cover, useful for sepsis/surgical prophylaxis

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