Chloramphenicol

Question 1

What is the mechanism of action for Chloramphenicol?

Answer 1

Reversibly binds to the larger 50S subunit of the 70S ribosome

Question 2

Why are serum concentrations of Chloramphenicol after IV therapy are only about 70% of those after oral administration?

Answer 2

Chloramphenicol must be hydrolyzed in the intestines to get activated
Therefore, suspension is more potent

Question 3

What can you say about CSF concentrations of Chloramphenicol?

Answer 3

Excellent 30-50% WITHOUT inflamed meninges

Question 4

Where is Chloramphenicol metabolized?

Answer 4

LIVER (glucuronidation)

Question 5

What bugs are covered by Chloramphenicol?

Answer 5

• Gram positive
• Gram negative
• Aerobic and anaerobic organisms
• Rickettsia
• Chlamydia

Question 6

What adverse reactions are associated with Chloramphenicol?

Answer 6

• Aplastic Anemia
• Gray Baby Syndrome (Abdominal distention, vomiting, cyanosis, circulatory collapse) because of lack of glucuronic acid conjugation system in neonates to degrade chloramphenicol
• Reversible Bone Marrow Depression

Question 7

Why isn’t Chloramphenicol used often?

Answer 7

Aplastic Anemia (shutting down of all cell lines)

Question 8

What is the mechanism behind toxicity of Chloramphenicol?

Answer 8

50S subunit of the 70S ribosome resembles that of mitochondrial ribosome; mitochondrial protein synthesis is inhibited

Question 9

When would Chloramphenicol be used?

Answer 9

• Bacterial meningitis (Haemophilus influenza, Strep pneumo, Neisseria meningitidis)
• B-Lactam allergic
• Oral alternative when IV cannot be used
• Rickettsial infections