Dosage form comprising solubility regulating member

Claim 1

A dosage form for delivering a beneficial drug formulation to a biological environment of use, wherein the dosage form comprises: (a) a wall comprising a composition that maintains its physical and chemical integrity during the life of the dosage form, is substantially impermeable to the passage of a beneficial agent formulation, and at least in part is permeable to the passage of exterior fluid present in the biological environment, which wall surrounds and forms; (b) a compartment; (c) a dosage amount of a beneficial drug formulation in the compartment; (d) means for aiding in controlling the solubility of the drug formulation in the presence of external fluid imbibed into the compartment, said means comprising a release rate controlling film selected from the group consisting of olefin and vinyl polymers, condensation polymers, addition polymers and organo-silicon polymers, which film surrounds a buffer that is released at a controlled rate by the film into the compartment for governing the solubility of the drug formulation and correspondingly aiding in osmotically and hydrodynamically delivering the drug formulation from the dosage form; and, (e) exit means in the wall of the dosage form that connects the internal compartment with the exterior environment of use for delivering the drug formulation in a therapeutically effective amount from the dosage form.