I will try to explain how the Medicare Part D plans work (Medicare Prescription Drug Coverage).
These type plans can be purchased as free-standing plans OR they can be within some Medicare Advantage plans. Either way, these plans should be evaluated by the beneficiary each year based on your individual needs during open enrollment. Medications change for the beneficiary as well as on the insurers formulary.
The Medicare Part D insurers must cover a select number of medication in each drug classification and in (5) classes they have to cover ALL of them. Each year they develop their formulary (list of the drugs they cover) including assignment of the tiers (price level) of the drugs.
They also assign any special circumstances to certain drugs for safety or cost control reasons like Quantity Limits, Step Therapy, Prior Approval and list these on their formulary.
Medicare.gov - What Medicare Part D drug plans cover
If one insurer doesn't cover what medication you need - as long as it is approved for seniors - another plan should probably have it in their formulary. Shop your plan during open enrollment
(October 15 – December 7, 2020).
That's why they are making suggestions to you (and your doctor), i.e. we aren't covering this med that you take but we are covering this other one that may suit your needs. There may be other circumstances why medications change even during the year - a drug that enters the generic market, a drug that is removed because of an FDA ruling,
If you and your doc are sold on one particular med, check other insurers in your area and change plans before open enrollment ends. You also have the right to file an appeal or ask for an exception.
Medicare.gov - Medicare prescription drug coverage appeals
Sometimes even NOT using the insurance coverage can give you a better (cash) price using places like Costco or GoodRx.
It's Always Something . . . . Roseanna Roseannadanna