On Jan 11, 2019, Federal Circuit affirmed PTAB’s decision of upholding the compound patent on Pfizer Inc.’s Toviaz® drug in an IPR challenge from Amerigen Pharmaceuticals Ltd.
UCB Pharma owns U.S. Patent 6,858,650 (expiring on 07/03/2022) patent, which covers certain chemical derivatives of 3,3- diphenylpropylamines, including a compound called fesoterodine. Fesoterodine is an antimuscarinic drug marketed as Toviaz® to treat urinary incontinence. Fesoterodine is a prodrug of the active compound 5-hydroxymethyl tolterodine (“5-HMT”). 5-HMT is a metabolite of the compound tolterodine, an older antimusarinic drug sold under the trade name Detrol® to treat overactive bladder. Fesoterodine differ s from 5- HMT at the 2-position : 5-HMT has a hydroxy group, while fesoterodine has an isobutyryl ester. The issue before federal circuit was whether it would have been obvious to modify the 2-position hydroxy group of 5-HMT to an alkyl ester of six carbons or less as in fesoterodine.