Adapter for which direction?
If you wanted to insert an AMR modem into a PCI slot, you would have been better off just buying a normal PCI modem, since they are both essentially WinModems; in most cases PCI modems are just a few dollars more expensive if not the same price as an AMR modem.
I can't see it going the other way as why would you want to plug a PCI card into an AMR slot? Besides, the components on the card are different, so that doesn't help either.