This document discusses the antibiotic chloramphenicol. It begins by stating that chloramphenicol is isolated from Streptomyces cultures and inhibits bacterial protein synthesis by binding to the 50S ribosomal subunit. It has broad-spectrum activity against gram-positive and gram-negative bacteria as well as rickettsiae. Resistance is caused by plasmid-mediated chloramphenicol acetyltransferase. It is absorbed rapidly after oral administration, widely distributed in tissues, and metabolized in the liver. While it can treat serious infections, it carries risks like bone marrow suppression and grey baby syndrome in newborns.

1. Prof. Shaikh Abusufiyan
Assistant Professor,
AIKTC-School of Pharmacy,
New Panvel-410206
Antibiotics: Chloramphenicol
Pharma Learning Forever

2. At the end of this e-learning session you are able to…
A. Discuss Mechanism of action of
chloramphenicol
B. Give classification and Explain
pharmacology of chloramphenicol.
Copyright @shaikhabusufiyan2021

3. CHLORAMPHENICOL
• Isolated from cultures of Streptomyces.
The mechanism of action:
• Chloraphenicol binds to the 50S subunit
of the bacterial ribosome at the same site
as erythromycin and clindamycin.
Inhibition of protein synthesis.

4. Antibacterial spectrum
• Wide spectrum of antimicrobial activity including
• Gram-negative
• Gram-positive organisms
• Rickettsiae.
• It is
• Bacteriostatic for most organisms
• Bactericidal to H. influenzae.

5. Resistance
• Caused by the production of
plasmid mediated
Chloramphenicol acetyltransferase

6. Pharmacokinetic aspects
Routs:
• Given orally- It absorbed rapidly and completely.
• Reaches its maximum concentration in the plasma
within 2 hours
• It can also be given parenterally.

7. Distribution:
• It is widely distributed throughout the tissues and body
fluids
• The CSF concentration --> may be 60% of that in the
blood.
• In the plasma -->it is 30-50% protein-bound
• Its half-life --> approximately 2 hours.

8. • About 10% is excreted unchanged in the urine
• And the remainder is inactivated in the liver.

9. Q&A
Q.1 What is the source of chloramphenicol?
Q.2 Give mechanism of action of chloramphenicol?
Q.3 What causes resistance to chloramphenicol?
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10. Activity I: Self learning of e-content

11. Clinical uses of Chloramphenicol:
• Should be reserved only for serious infections in
which the benefit of the drug is greater than the risk
of toxicity, such as:
• Infections caused by Haemophilus influenzae resistant to
other drugs
• Meningitis in patients in whom penicillin cannot be used.

12. Clinical uses of Chloramphenicol.........
• It is also safe and effective in bacterial
conjunctivitis (given topically).
• It is effective in typhoid fever but ciprofloxacin
or amoxicillin and cox-trimoxazole are similarly
effective and less toxic.

13. Unwanted effects
• Severe, idiosyncratic depression of the
bone marrow
resulting in pancytopenia - even with very
low doses in some individuals.

14. • Chloramphenicol should be used with great care in
newborns because inadequate inactivation and excretion of
the drug can result in the 'Grey baby syndrome'
• 'Grey baby syndrome'-
• vomiting, diarrhoea
• flaccidity
• low temperature
• An ashen-grey colour
• carries a 40% mortality

15. • Hypersensitivity reactions
• Gastrointestinal disturbances -
alteration of the intestinal microbial
flora.

16. Q&A
Q.1 Enlist any 3 clinical uses of chloramphenicol?
Q.2 How chloramphenicol causes pancytopania?
Q.3 Enlist symptoms of Gray Baby syndroms?
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17. Reference:
• H.P Rang. M M Dale, J.M Ritter, R.J Flower, G Henderson.
Pharmacology, Seventh Edition. Elsevier Churchill Livengston
Publication. Page no:630-631.
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