Mechanism of action


       Drug interactions

       Adverse effects

       Clinical uses


At the end of this session, students will be able to:

       Describe the mechanism of action of Chloramphenicol

       Outline the pharmacokinetics of Chloramphenicol

       Explain the drug interactions and clinical uses of Chloramphenicol


       Broad spectrum antibiotic

       Isolated from Streptomyces venezuelae

       Contains nitro group as nitrobenzene moiety

Mechanism of action

       Inhibits bacterial protein synthesis

       Binds 50S subunit and block elongation

       Inhibits the formation of initiation complexes and peptidyltransferase;

       Binding site overlaps with that of macrolides and clindamycin

       Primarily bacteriostatic

       May be bactericidal to some strains of microorganisms even at lower concentration

Binding site of chloramphenicol

Mechanism of resistance

       Selection of permeability mutants

       Results in impaired penetration of the drug to target site

       Production of chloramphenicol acetyltransferase, a plasmid-encoded enzyme that inactivates the drug

Antimicrobial spectrum

       active against a broad range of organisms, including G+ and G-bacteria (including anaerobes)

       Effects on G- bacteria is better than on G+ bacteria, especially Salmonella typhi

       At low concentration effective against H. influenzae, N. meningitidis and N. gonorrhoeae


       Administration in crystalline form

       Parenteral – Chloramphenicol sodium succinate

       Oral – Chloramphenicol palmitate

       Oral  - rapid and complete absorption

       Widely distributed

       Metabolized by glucuronyl transferase and aryl amide

       30-60% protein bound

       Secreted in breast milk

       75-90% excreted in inactive form through kidneys

       Small amount in bile

Adverse effects

Bone marrow Disturbance

       Reversible bone marrow depression

       Chloramphenicol inhibits protein synthesis in the mitochondria of human cells

       Dose dependent toxicity of drug to bone marrow

Toxicity for Newborn Infants (Gray-baby syndrome)

       In neonates, especially premature infants

       Given relatively large doses of chloramphenicol

       Cyanosis, respiratory irregularities

       Abdominal distention, loose green stool, and an ashen-gray color

       Gastrointestinal reaction. nausea, vomiting, diarrhea

        Super infections such as Oropharyngeal candidiasis and acute Staphylococcal enterocolitis

       Hypersensitivity reactions

       A rare anaemia, probably immunological in origin but often fatal

Drug interactions

       Paracetamol increases the bioavailbility of chloramphenicol

       Cloramphenicol -  enzyme inhibitor

       Inhibits the metabolism of morphine, chlorpropamide and warfarin

Clinical uses


       Typhoid fever

       Sepsis caused by gram negative organisms

       Bacterial fragilis

       Rickettsial disease

       Topically used for eye and ear infection


       Chloramphenicol is a broad spectrum antibiotic isolated from Streptomyces venezuelae and it contains nitro group as nitrobenzene moiety

       Binds 50S subunit, block elongation and inhibits the formation of initiation complexes by inhibiting peptidyltransferase

       Used for the treatment of bacterial fragilis, meningitis, Typhoid fever

       Associated with sever adverse effects like gray baby’s syndrome and bone marrow depression


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