Controlled release dosage form having improved drug release properties

A commercial scale, multi-batch process for preparing a controlled release bead comprising the steps of:

• (a) providing a core unit of substantially water-soluble or water-swellable material;
• (b) applying a first layer of a substantially water-insoluble polymer to said core;
• (c) applying onto said first layer a second layer comprising tolterodine or a tolterodine-related compound and optionally a polymer binder;
• and
• (d) applying onto said second layer a third polymer layer comprising an aqueous polymer dispersion;
• wherein the amount of material in said first layer is selected to provide a layer thickness that permits control of water penetration into the core;
• and
• (e) standardizing age, at time of batch preparation, of the aqueous polymer dispersion such that the age varies among substantially all of said batches by not more than about 180 days.