Retapamulin is the first agent in the new pleuromutilin class of antibacterials 
to become commercially available for clinical use in humans. Retapamulin acts as 
a potent inhibitor of bacterial protein synthesis and has a unique mode of 
antibiotic action. To date, retapamulin has not demonstrated any clinically 
relevant, target-specific crossresistance with other antibiotic classes, and has 
shown a low potential for resistance selection in vitro. In preclinical studies, 
retapamulin demonstrated pronounced in vitro activity against staphylococcal, 
streptococcal and anaerobic Gram-positive clinical isolates associated with skin 
and skin structure infections. Clinical pharmacology studies showed low systemic 
exposure with topical use of retapamulin, and a favorable tolerability profile. 
In clinical efficacy trials involving pediatric and adult patients who received 
retapamulin twice daily for five days, retapamulin was highly effective in the 
treatment of impetigo, secondarily infected traumatic lesions and secondarily 
infected dermatitis. Further, the clinical efficacy and safety profile of 
retapamulin was comparable to that of commonly used oral and topical 
antibiotics. Retapamulin was also clinically effective against isolates 
resistant to existing therapies. As a 1% ointment, retapamulin has been approved 
in the United States for the treatment of impetigo and in Europe for the 
shortterm treatment of impetigo and infected small lacerations, abrasions and 
sutured wounds.