Macrolides

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Macrolides

Mode of action

• bind to 50S subunit of ribosomes (does not exist in human cells). More specifically to the peptidyl transferase site
• thought to block peptide bond formation of peptidyl tRNA translocation from A to P site
• ? promote premature dissociation of peptidyl tRNA from ribosome during elongation process with resultant incomplete peptides
• ? erythromycin (but not other macrolides) prevents assembly of 50S subunit
• anti-inflammatory effects
• erythromycin also promotes gastric motility

Resistance

• modification of bacterial target and therefore affects all macrolides as well as lincosamides and streptogramins

Pharmacodynamics

• bacteriostatic except at high concentrations and therefore target site concentration needs to be consistently maintained above MIC
• macrolides, streptogramins, lincosamides and chloramphenicol have antagonistic pharmacological action as their mode of action is similar

Further reading

Van Bambeke F. Mechanisms of action. In Armstrong D, Cohen J. Infectious diseases. Mosby, London, 1999, pp7/1.1-7/1.14

Giamarellos-Bourboulis EJ.  Macrolides beyond the conventional antimicrobials: a class of potent immunomodulators.  Int J Antimicrob Agents, 2008; 31:12-20

©Charles Gomersall, October, 2009 unless otherwise stated. The author, editor and The Chinese University of Hong Kong take no responsibility for any adverse event resulting from the use of this webpage.
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