My wife encountered the opposite. After self injecting Cimzia at home for years, she was told that Medicare did not cover it in Part D as a prescription drug. However, they will cover it as a service at a doctor's office under Part B, at a cost of around $5500 per month!
We are lucky that we enrolled in a supplemental plan that covers all medical costs after her $185 deductible per year!
However, we now have to drive 2 hours to the doctor's office so she can get the injection that she used to do herself.