I found this in the comments over at Corrente and wanted to share it:

Insurance companies reserve the right to make changes to their formularies at any time, but are supposed to notify you and allow you one month's supply of your current drug in order to give your medical provider the opportunity to "pre-authorize" your access to said drug. Your doctor cannot simply write a letter saying "I'm the doctor by god, and I want the patient to have this drug". No, he must provide evidence that he has "stepped" you. Stepped means that he/she has tried you on "approved" A, B and C drugs to little or bad results first.

Now, A and C may no longer be on the formulary, so they don't count, so he/she has to find out what approved drugs are on the formulary so that he/she can say that they have been tried and if that is true, or he/she will say it is true, then it will go to the Pre-Authorization department.

If the PA department can't sort it, say because your diagnosis does not fit neatly into what the insurance company says the drug can be used for, albeit that it works for what ails you, the application goes to the in-house pharmacist. The in-house pharmacist (average salary $90,000 per annum) will make the final decision based on following company guidelines and keeping his/her job. If the decision is that you get the drug, then said drug will be approved for you as "off formulary", moved to class 3 and if your co-pay was $25.00, it will now be $60.00 or more.

If the drug is not approved, then you will be properly stepped with the ineffective, approved drugs before your pre-authorization can be reconsidered. After you have been stepped, the drug will still be off formulary and the co-pay will still be increased. It sucks and I am so sorry.

Signed Anguished in the PA Department - United Health Insurance Inc