Chloramphenicol

Summary

Chloramphenicol is an antibiotic that works by binding the 50S subunit of bacterial ribosomes to prevent bacterial protein synthesis. The drug is used as a second or third line therapy for bacterial meningitis and to treat rickettsial diseases. Adverse effects of chloramphenicol include gray baby syndrome, anemia which is dose-dependent, and aplastic anemia which is dose independent.

Key Points

• Chloramphenicol
  • Mechanism
    • Reversibly binds 50S subunit of bacterial ribosomes
      • Blocks peptidyltransferase and inhibits bacterial protein synthesis
    • Bacteriostatic
  • Clinical Use
    • Meningitis
      • e.g. H. influenzae, N. meningitidis, S. pneumoniae
    • Rickettsial diseases
  • Adverse Effects
    • Anemia (dose-dependent)
      • Anemia, leukopenia, thrombocytopenia are all possible
      • Reversible by stopping medication
    • Aplastic anemia (dose-independent)
      • Thought to result from autoimmunity induced by drug
      • Usually severe and fatal without bone marrow transplantation
    • Gray-baby syndrome
      • Presents in babies as gray skin, vomiting, lethargy, and cardiorespiratory suppression
      • Premature infants lack liver UDP-glucuronosyltransferase and cannot metabolize the drug, leading to toxic accumulation
  • Resistance
    • Plasmid-encoded acetyltransferase inactivates the drug