1. Part D plans generally include drugs commonly used by dual eligibles: 2018 Publication: [Washington, D.C.] : U.S. Department of Health and Human Services, Office of Inspector General, June 2018 Subject(s): Drug UtilizationDual MEDICAID MEDICARE EligibilityFormularies as TopicMedicare Part DInsurance BenefitsInsurance, Pharmaceutical ServicesHumansUnited StatesUnited States. Department of Health and Human Services.United States.