Life after retirement is a disturbing thought for many senior citizens. There are loans to repay; family's financial needs like daily expenses of the household, children's education, marriages, utilities, etc. need to be fulfilled; add to it the extra burden of diseases and disabilities that come with advancing age. What most people dread more than illness is the cost of medicines that go up day by day. Expensive prescription drugs can slowly drain the nest egg you have built over the years. That is why most people invest in health insurance programs that will support them in their old age. Medicare is one such medical benefit program administered by the U.S government to provide the senior citizens of the country proper medical care during the post-retirement period. This program includes four parts with each one catering to a specific area of medical care. Medicare Part D covers prescription drugs; it subsidizes the cost of prescription drugs and is available for Medicare beneficiaries who have enrolled in Part A or Part B of the program. Medicare Part D plans are offered by private health insurance companies approved by Medicare.

Any individual who is 65 years of age or above and has resided in the United States for at least five years is eligible for enrolling in the Medicare Part D program. The age threshold can be exempted for individuals with certain disabilities who qualify some criteria set by Medicare. Only those people who already have enrolled in the Original Medicare Plan (Part A and Part B) can buy Medicare Part D. Two types of prescription drug plans are available for the enrollees: stand-alone Prescription Drug Plan (PDP) and Medicare Advantage Plan with prescription drug coverage (MA-PD). PDP is exclusively for prescription drug discounts while MA-PD also offers medical services. PDP is more useful for the beneficiaries of the Original Medicare plan as it does not have prescription drug coverage; they can buy the Part D plan and add it to the Original Medicare Plan. The MA-PD plan is the Medicare Part C program that includes prescribed drug coverage in its benefits.

The Part D plans have regional variations and the cost of medicines also can change accordingly. When a person enrolls in a Medicare Part D plan, he is assigned a geographical area in which his plan is applicable. Pharmacies outside this are or those that do not participate in the particular Part D plan usually do not provide the prescription drug plan services.