Hi Michael, welcome to the community.  Generally Medicare Part B pays 80% of the assigned/approved amount of a drug or treatment.  To find out what this figure actually is, ask your Dr - the one rxing the drug - what the MC Part B copay would be; your Dr. should know this from the info on his or her other patients.  If you can't get an answer from the Dr. you can also call the infusion centers billing office and ask this question there.  If these 2 options don't pan out, call 1-800-Medicare and ask how much you would have to pay.  I would also ask your Dr. if this drug needs "prior authorization" for MC to pay for it.  I'm not sure if this step is necessary, but it wouldn't hurt to find out because if it is required it could speed up the process.  Prior authorizations typically take from 24-72 hours for approval, and the Drs office handles the whole thing and knows what to do.  Here's an article on Reclast that gives a link on how to find the nearest infusion center for you.

Good luck with this and if you have any other questions don't hesitate to re-post.