For use in adults and pediatric patients aged 9 months and older for the topical treatment of impetigo (up to 100 cm2 in total area in adults or 2% total body surface area in pediatric patients aged 9 months or older) due to Staphylococcus aureus (methicillin-susceptible isolates only) or Streptococcus pyogenes.
Retapamulin is a semisynthetic pleuromutilin antibiotic. This drug is usually bacteriostatic in action, but may become bactericidal at highed concentrations (when MBC is 1000 times higher than MIC). Retapamulin acts by selectively inhibiting the initiation of protein synthesis in bacteria at the level of bacterial 50S ribosome.
Mode of Action:
Retapamulin is a bacterial protein synthesis inhibitor belonging to a class of compounds called pleuromutilins. These compounds inhibit the initiation of protein synthesis by binding to a specific site on the 50S subunit of bacterial ribosome (domain V of 23S rRNA). This binding site involves ribosomal protein L3 and is in the region of the ribosomal P site and peptidyl transferase center. By virtue of binding to this site, pleuromutilins inhibit peptidyl transfer, block P-site interactions, and prevent the normal formation of active 50S ribosomal subunits.
In vitro studies with human liver microsomes demonstrated that retapamulin is extensively metabolized to numerous metabolites, of which the predominant routes of metabolism were mono-oxygenation and N-demethylation. The major enzyme responsible for metabolism of retapamulin in human liver microsomes was cytochrome P450 3A4 (CYP3A4).
CenterWatch LinkJones RN, Fritsche TR, Sader HS, Ross JE: Activity of retapamulin (SB-275833), a novel pleuromutilin, against selected resistant gram-positive cocci. Antimicrob Agents Chemother. 2006 Jul;50(7):2583-6. PubmedYang LP, Keam SJ: Retapamulin: a review of its use in the management of impetigo and other uncomplicated superficial skin infections. Drugs. 2008;68(6):855-73. PubmedNovak R, Shlaes DM: The pleuromutilin antibiotics: a new class for human use. Curr Opin Investig Drugs. 2010 Feb;11(2):182-91. PubmedJacobs MR: Retapamulin: a semisynthetic pleuromutilin compound for topical treatment of skin infections in adults and children. Future Microbiol. 2007 Dec;2:591-600. PubmedParish LC, Parish JL: Retapamulin: a new topical antibiotic for the treatment of uncomplicated skin infections. Drugs Today (Barc). 2008 Feb;44(2):91-102. PubmedRetapamulin for impetigo and other infections. Drug Ther Bull. 2008 Oct;46(10):76-9. PubmedNagabushan H: Retapamulin: a novel topical antibiotic. Indian J Dermatol Venereol Leprol. 2010 Jan-Feb;76(1):77-9. PubmedShawar R, Scangarella-Oman N, Dalessandro M, Breton J, Twynholm M, Li G, Garges H: Topical retapamulin in the management of infected traumatic skin lesions. Ther Clin Risk Manag. 2009 Feb;5(1):41-9. Epub 2009 Mar 26. Pubmed
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