Finally, comparisons between AD and AP users by the number of unique medications (Q6) and therapeutic classes of medications used are provided (Q7). 3 Methodology Study Population The study population was comprised of Medicare Part D enrollees who used AP or AD medications, and is defined as beneficiaries who had one or more prescription drug event (PDE) claim(s) for an AD or AP medication in the 2012 Standard Analytic File (SAF) accessed February 10, 2014. Part D enrollees in standalone Prescription Drug Plans (PDPs) and Medicare Advantage Prescription Drug Plans (MA-PDs) were included in this analysis. Antidepressant and Antipsychotic Medications, Unique Drugs and Drug Names, Therapeutic Classifications, and Fills AD and AP medications were identified from an internally developed list of National Drug Codes (NDCs) that were active during 2012. Unique drugs were defined at the Medi-Span Generic Product Identifier (GPI-10) level which identifies a drug by its generic entity name (e.g., nortriptyline hydrochloride or megestrol acetate instead of Pamelor® or Megace®).