• Eline A. Dubois,

  • Adam F. Cohen

  • In this series we draw attention to recently licensed medicines with an entirely new mechanism of action. Publication does not imply endorsement of use in clinical practice. Copyright to the images belongs to Leiden University, but use of the images (available at is free.


Bacterial skin infections caused by Staphylococcus aureus and Streprococcus pyogenes strains are sensitive to the bacteriostatic effects of retapamulin.


Retapamulin is an antibiotic in the new class of pleuromutilins. Pleuromutilin is a natural antibacterial product derived from the fungus Clitopilus passeckerianus.

In common with macrolides, tetracyclines and aminoglycosides, retapamulin inhibits bacterial protein synthesis, but binds to a different site on ribosomal subunit 50S.

Retapamulin specifically binds in the region of the P-site and peptidyl transferase centre. By virtue of binding to the peptidyl transferase centre, retapamulin inhibits the transfer of the developing amino acid chain onto the following tRNA. Other mechanisms of retapamulin include partially blocking P-site interactions and preventing normal formation of active 50S ribosomal subunits.

Because of its distinct mechanism of action, target specific cross-resistance with other antibiotics does not occur.

Adverse effects

Irritation at the application site is the most common adverse effect.


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