Efficacy and Tolerability of Retapamulin 1% Ointment for the Treatment of Infected Atopic Dermatitis: A Pilot Study

July 2012 | Volume 11 | Issue 7 | Original Article | 858 | Copyright © July 2012


Abstract
Background: Patients with atopic dermatitis (AD) are known to have a predisposition to colonization or infection by microbial organisms, including both Staphylococcus aureus and herpes simplex virus (HSV). S aureus infection leads to exacerbation of eczema and may induce flares in atopic skin by mediating inflammation. Retapamulin 1% ointment is a unique topical antibiotic formulation that may be a suitable option for the treatment of clinically infected AD.
Study Design: A single-center, open-label pilot study was conducted to investigate the efficacy and safety of retapamulin 1% (Altabax, Stiefel/ GlaxoSmithKline) ointment for the treatment of secondarily infected atopic dermatitis in subjects aged 9 months to 98 years old (n=29).
Results: Twice-daily application of retapamulin 1% produced a mean 8.1-point reduction from baseline in the mean Skin Infection Rating Scale score. The majority of subjects achieved clinical cure with topical retapamulin therapy. Retapamulin 1% ointment was effective against S aureus isolates, including methicillin-resistant Staphylococcus aureus (MRSA). Treatment was well tolerated.
Conclusion: Retapamulin 1% is effective for the treatment of atopic dermatitis infected with S aureus, and demonstrates efficacy against both methicillin-susceptible and methicillin-resistant strains. Given its efficacy and good tolerability in this pilot study, retapamulin 1% ointment should be further evaluated as a treatment for infected atopic dermatitis. It may provide convenience and efficacy with a low risk for development of bacterial resistance.

J Drugs Dermatol. 2012;11(7):858-860.

INTRODUCTION

Patients with atopic dermatitis (AD) are known to have a predisposition to colonization by microbial organisms, including both Staphylococcus aureus and herpes simplex virus (HSV).1 In fact, S aureus is considered a critical cofactor in AD.2 In recent years, increased attention has been paid to methicillin-resistant strains of S aureus, (MRSA), which is identified in both hospital-acquired (HA) and community-acquired (CA) strains. Community-acquired MRSA has been identified in AD patients, but studies suggest a low incidence of MRSA among AD patients.3,4 In one analysis, there was a significantly lower rate of CA-MRSA among pediatric AD patients than in the general pediatric population.4
Staphylococcus aureus infection leads to exacerbation of eczema and may induce flares in atopic skin.5,6 Suspected mechanisms for Staphylococcus-mediated inflammation include production of inflammatory cytokines following either direct infection of keratinocytes or immune cells or indirectly by bacterial byproducts.6 Antibacterial therapy aimed at reducing the bacterial load is considered a standard approach to care for infected, flaring AD, although antibiotic therapy in non-clinically infected individuals is not recommended.7 Topical mupirocin is an established choice for the management of infected AD, although it has been associated with some degree of antibacterial resistance, leading to calls for judicious use.8 Retapamulin 1% ointment is a relatively novel topical antibiotic formulation that may be a suitable alternative for the treatment of clinically infected AD.
Retapamulin 1% ointment is indicated for use in adults and pediatric patients 9 months to 98 years of age for the topical treatment of impetigo due to methicillin-susceptible S aureus or Streptococcus pyogenes. In vitro, retapamulin is highly potent against S aureus and has a lower propensity to develop resistance than mupirocin.9,10 Furthermore, clinical studies suggest the fiveday BID dosing schedule is effective against impetigo due to methicillin-susceptible S aureus and S pyogenes.
The first and only prescription topical antibacterial in the pleuromutilin class, retapamulin confers its antibacterial effects via its effects on 3 different aspects of microbial protein synthesis. It prevents normal formation of the 50S ribosomal subunit.11 Additionally, it is shown to block P-site interactions and inhibit peptidyl transfer by bacterial cells.12

STUDY DESIGN

A single-center, open-label pilot study was conducted to investigate the efficacy and safety of retapamulin 1% (Altabax,