A Part D prescription drug plan, also known as “PDP”, is one of two main ways Medicare beneficiaries can enroll in Medicare coverage for prescription drugs. The Medicare Part D benefit is offered through private insurers, either as a stand-alone Part D plan (PDP) or a Medicare Advantage plan that has prescription drug benefits (MAPD). A PDP can be purchased by beneficiaries with Original Medicare coverage (with or without a Medigap plan) and – in some cases –by Medicare Advantage (MA) beneficiaries who don’t have a prescription drug benefit included in their MA plan.