In my situation once a drug is preauthorized that's it..no more authorization needed. I am going through that with BP med right now. The insurance co. wanted me to try and old cheap drug first before they would allow coverage on a new expensive drug. It was all a surprise when I went to get the newer drug filled and the pharmacist said it was not covered by Express-Scripts. The doc did not know of this situation either but after many calls and explanations he caught on. My trial period is over and now I may use the newer drug.

Now..Express-Scripts had provided a website for its members so they can check what is covered and what is not covered. Extensive lists of various meds are posted with pricing.

In some cases like Xanax there is 0 coverage but if you use a cheaper drug almost identicle to Xanax it is covered.
jb