Dosage form with improved delivery capability

Claim 1

A dosage form for delivering a beneficial agent to the fluid environment of use, comprising: (a) a wall in at least a part a semipermeable composition permeable to the passage of an exterior fluid and substantially impermeable to the passage of a beneficial agent, which wall surrounds and forms: (b) a compartment; (c) a first layer comprising a beneficial agent in the compartment, which layer forms in situ a dispensable aqueous formulation comprising the beneficial agent with aqueous fluid that enters the compartment; (d) a third layer comprising hydrogel means for expanding and occupying space in the presence of fluid in the compartment; (e) a second layer pressed laminated into laminar arrangement between the first and third layer in the compartment, said second layer comprising a thickness of 1 to 7 mm and a permeability constant not more than about 1.0×10 -5 cm 2 /hr and being a separate and distinct layer comprising a different composition than the first and third layers, which second layer comprises a non-expandable hydrophobic composition that is a means for substantially preventing the migration of the beneficial agent from the first layer comprising the dispensable aqueous formulation into the third layer; and, (f) means in the wall connecting the exterior of the dosage form with the compartment.