FDA begins review of GSK antibiotic

Retapamulin belongs to a new class of antibiotics and is being developed as a topical treatment for uncomplicated skin and skin structure infections due to susceptible strains of staphylococcus aureus and streptococcus pyogenes. Retapamulin has been studied for use twice a day for a five-day period.

GlaxoSmithKline submitted the new drug application (NDA) to the FDA in November 2005 and expects to receive approval to market the product later this year. The clinical trials for retapamulin involved 2,450 patients worldwide. The NDA is based on phase III data involving 712 patients across the US.

Laboratory studies recently presented at the 45th Interscience Conference of Antimicrobial Agents and Chemotherapy (ICAAC) demonstrated that retapamulin showed a high degree of in vitro potency against key pathogens commonly associated with skin and skin structure infections, consistently showing potent activity when compared to other commonly prescribed topical and oral antimicrobial agents.

Furthermore, retapamulin demonstrated a low propensity for development of resistance in target pathogens.

Continued widespread use of antibiotics has promoted the spread of antibiotic resistance and has created an urgent need for antibacterial agents with no known cross resistance.

Retapamulin is the first in a new class of antibiotics called pleuromutilins and demonstrates a unique mechanism of action. By binding to a distinct site on the 50s sub-unit of the bacterial ribosome, retapamulin inhibits protein synthesis; in vitro, retapamulin has shown no target-specific cross-resistance to other established classes of antibiotics.