Retapamulin, a topical pleuromutilin antibiotic, is the first in a new class of topical antibiotics approved for human use. In the United States (US), retapamulin is approved for the treatment of impetigo in persons nine or more months of age and was launched on 12 April 2007. This five-year study is designed to examine use of retapamulin in the pediatric population less than nine months of age. We will conduct an annual assessment of prescription sales claims for retapamulin using the Integrated Health Care Information Services (IHCIS) National Managed Care Benchmarked Database. For each year of reporting, the observed frequencies of the exposure, with or without same-day, co-prescribed sales claim of mupirocin, will be identified. The study objectives are to determine the frequency of retapamulin sales in a representative US population stratified by the designated age group and to determine the frequency of same-day sale of the topical agent, mupirocin.

The IHCIS is Health Insurance Portability and Accountability Act (HIPAA) compliant with encrypted member and provider identifiers; date of birth is restricted to year of birth. Based on year of birth and the prescription sales claim date, age at the time of the prescription(s) will be categorized as less than 9 months (definitive) and less than 9 months (uncertain).

Inclusion Criteria:

• The study population will consist of all 'eligible members' in the IHCIS database with a valid gender and age record who have at least 1 month enrolment and eligibility of pharmacy benefits.

Exclusion Criteria:

• Membership in IHCIS without a valid gender or age record, enrolment less than 1 month, or ineligibility for pharmacy benefits will be excluded.

Members with enrollment and phamacy benefits eligibility in the Integrated Health Care Information Services (IHCIS) National Managed Care Benchmarked Database will be assessed annually for prescription sales claims for five years post-launch of retapamulin. The IHCIS is a US national managed care database which is Health Insurance Portability and Accountability Act (HIPAA) compliant and features encrypted member and provider identifiers.