Chloramphenicol

• What is the name of the antibiotic discussed in the study material?

  Chloramphenicol
• What are the chemical characteristics of chloramphenicol?

  • Nitrobenzene derivatives
  • Low molecular weight
• What is the mechanism of action of chloramphenicol?

  It binds to the 50S ribosomal subunit and inhibits peptidyl transferase enzyme.
• How does chloramphenicol affect protein synthesis?

  It blocks transpeptidation of the peptide chain to aminoacyl-tRNA.
• What is the consequence of chloramphenicol blocking the binding of aminoacyl moiety to the "A" site?

  It prevents the peptidyl transferase enzyme from transferring the growing chain, stopping protein synthesis.
• Why does chloramphenicol inhibit mitochondrial ribosomal protein synthesis?

  Because mitochondrial ribosomes are 70S, similar to bacterial ribosomes.
• What is the mechanism of resistance (MOR) for chloramphenicol?


  It is "r" plasmid mediated, imparting CAP-acetyl transferase activity and altering the 50S ribosomal binding site.
• What is the significance of promiscuous plasmids in relation to chloramphenicol?

  They cause microbes to become resistant to many other antibiotics of different classes.
• What is the antimicrobial activity of chloramphenicol?

  • Basically bacteriostatic
  • Bactericidal for:
  • H. influenzae
  • Neisseria meningitidis
  • Some bacteroids
  • Streptococcus pneumoniae
  • Broad spectrum activity against:
  • Rickettsia
  • Chlamydia
  • G+ve cocci
  • G-ve rods
  • Clostridia
• How is chloramphenicol absorbed in the gastrointestinal tract?

  It is well absorbed due to its low molecular weight, and absorption is not affected by food.
• What is the distribution characteristic of chloramphenicol?

  It easily penetrates tissues, including the brain, prostate, and breast milk.
• What is the half-life of chloramphenicol?

  1.5-3.5 hours
• What are the clinical uses of chloramphenicol?

  It is reserved for life-threatening infections, especially CNS infections and anaerobic infections.
• What are the side effects of chloramphenicol?

  Bone marrow depression, reversible anemia, and aplastic anemia.
• What is Grey Baby Syndrome and its cause?

  It is seen in neonates due to immature glucuronide conjugation enzymes and poorly functional kidneys.
• In which age group should chloramphenicol not be used?

  In children less than 1 month old.
• How does chloramphenicol interact with other drugs?

  It inhibits hepatic microsomal cytochrome P450 enzymes, prolonging the half-lives of many drugs.
• What are the drugs whose effects are prolonged by chloramphenicol?

  • Phenytoin
  • Tolbutamide
  • Chlorpropamide
  • Warfarin