3. ANTIMICROBIAL SPECTRUM
Broad spectrum antibiotic
Active against both aerobic and anaerobic
Gram +ve & gram –ve bacteria, Rickettsiae,
Mycoplasma
Primarily Bacteriostatic
High concentrations bactericidal effect
on some bacteria i.e.
H. Infleunza, N. meningitidis,
Bacteriodes
4.
5. MECHANISM OF ACTION
Potent inhibitor of
microbial protein
synthesis
Reversibly binds to the
50S ribosomal subunit
of the bacteria & inhibits
the peptidyl transferase
step of protein synthesis
Probably by acting as
peptide analogue , it
prevents the formation
of peptide bonds
6.
7.
8.
9. RESISTANCE
• Production of chloramphenicol
acetyltransferase, a plasmid-encoded
enzyme that inactivates the drug
• Decreased permeability of drug
• Lowered affinity of bacterial ribosomes
for chloramphenicol
Clinically
significant
resistance
10. PHARMACOKINETICS
Usual dosage: 50-100mg/kg/d
Half life: 3-5 hours
Rapidly & completely absorbed after oral
ingestion
50 to 60% plasma protein bound
Very widely distributed
CSF concentration nearly equal to
that of unbound drug in plasma
Primarily conjugated with
glucuronic acid in the liver
Excreted in the urine (10% active
& 90% inactive)
11. CLINICAL USES
Intraocular infections
Serious Rickettsia infections i.e.
Typhus, Rocky mountain spotted
fever
Meningococcal meningitis
occurring in patients who have
major hypersensitivity reactions to
penicillin
Bacterial meningitis caused
by penicillin – resistant
strains of pneumococci
As an alternative to Metronidazole
& Clindamycin in Anaerobic
infections ( wound infection, pelvic
& brain abscess) caused by
bacteroid fragilis
13. DRUG INTERACTIONS
Inhibits hepatic microsomal
enzymes that metabolize
several drugs
Increases serum concentrations
of Phenytoin, Warfarin,
Tolbutamide, Chlorpropamide,
Cyclophosphamide
Being Bacteriostatic it can
antagonize the bactericidal
action of penicillin &
aminoglycosides
