Do not forget the fact that the key AMRI patents cover the cost effective process by which it (fexofenidine) is manufactured. Further, patent term extension under waxman hatch may not have been fully addressed.
The patents that you cite refer to the old Seldane patents. They are the original patents to describe the general class of compounds. The key patents are the ones filed by AMRI which cover the manufacturing process to make Allegra. The original patents do not describe this process. The Allegra patents are current and will not expire for 8-10 years.