Medicare Part D - one more idiocy

One more idiocy of Medicare Part D. I turned 65 this month, so I switched from my previous health care plan to Medicare and from no drug coverage to Medicare Part D under a plan sponsored by Humana. Recently, I called the pharmacy to order refills on one of my prescriptions and forgot to tell them I was under a new drug plan. When I went in to pick up the prescription, they handed me to drugs and the invoice for $22.50. At that point, I remembered that I was now on Medicare Part D and handed them my card. Since the plan I'm on has an initial deductible of $250.00 I knew I would pay the full price of the drug, so I began to write a check. The pharmacist warned me to stop because the price would be different under the plan. Bingo, the approval from Humana came through, and the pharmacist had to charge me $28.50, six dollars more that I would have had to pay when I was uninsured!

Tell me how that makes sense.