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Medicare prescription drug coverage

Within Medicare Part D, there are two plan types to choose from — prescription drug plans (PDPs) and Medicare Advantage prescription drug plans (MAPDs). Expand each question below to learn more about Medicare Part D coverage.

Medicare prescription drug coverage (Part D) is offered through private insurance companies, like Aetna and SilverScript. You can get Part D coverage through a stand-alone prescription drug plan (commonly referred to as a PDP) or some Medicare Advantage plans (commonly referred to as a MAPD or Part C). 

A prescription drug plan (PDP) is a stand-alone Medicare Part D plan. PDPs only offer Part D and work together with your Original Medicare. This is a good option for someone who wants to stay in Original Medicare but add prescription drug coverage.

You are eligible to enroll in a PDP if you are already enrolled in Medicare Part A and/or Medicare Part B. Medicare Part D Prescription Drug Plans are only available through private insurers such as Aetna and SilverScript.


For more information, please visit our Unpacking Medicare prescription drug coverage page.

A Medicare Advantage prescription drug plan (or MAPD) is a plan — from a private insurer such as Aetna — that combines all your health coverage into one plan.


A MAPD plan includes:

  • Medicare Part A (hospital)
  • Medicare Part B (medical)
  • Medicare Part D (prescription)


Like other health plans, MAPDs come in various forms, such as HMOs (health maintenance organizations) and PPOs (preferred provider organizations).

There are four stages of Medicare Part D coverage that may change what you pay for covered prescriptions (aside from your plan premium) over the course of a year.

  1. The annual deductible stage - You begin in the annual deductible stage (if your plan has a deductible). You pay the full cost of your covered prescriptions until you reach your deductible. Keep in mind, some prescriptions may not apply to the deductible.

  2. The initial coverage stage - This is the stage after you have met your deductible (if it applies) and before your total drug costs have reached the initial coverage limit. Total drug costs include what you have paid and what your plan has paid.

  3. The coverage gap stage - The coverage gap begins after you and your drug plan together have spent a certain amount for covered drugs and have reached the initial coverage limit. When you’re in the coverage gap, you will pay no more than 25% of the cost for your plan's covered brand-name or generic prescription drugs. The coverage gap ends when you have spent enough to qualify for catastrophic coverage. Some people will never enter the coverage gap because their drug costs won’t be high enough.

  4. The catastrophic coverage stage - This is the drug coverage stage that happens after you get out of the   coverage gap (donut hole). With catastrophic coverage, you pay a reduced amount for covered drugs for the rest of the year.
  • Each plan has a drug list (formulary) that shows which drugs it will cover. Both generic and brand drugs are covered under Part D. Visit our formulary FAQ page to learn more.
  • A generic drug is a prescription drug that is approved by the Food and Drug Administration (FDA) as having the same active ingredient(s) as the brand-name drug. Generally, a “generic” drug works the same as a brand-name drug and usually costs less.
  • A brand-name drug is a prescription drug that is made and sold by the company that originally researched and developed the drug. A brand-name drug has the same active ingredients and formula as its generic version.

Here are some examples of what Part D prescription drug plans do not cover:


  • Drugs given in hospitals or doctors’ offices that are already covered under Part A or Part B
  • Any drugs not listed on a plan’s drug formulary (except in special circumstances)
  • Nonprescription drugs or prescription vitamins (other than prenatal vitamins). Examples include weight loss or weight gain, hair growth and/or erectile dysfunction drugs.


For a more complete list of drugs not covered by Medicare, please visit our Prescription drug formulary FAQ page.

Aetna Medicare and SilverScript Part D plans cover the shingles vaccine and some commercially available vaccines. Part D in general covers recommended adult immunizations when needed to prevent illness. Talk to your provider about which ones are right for you.

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