Swelling modulated polymeric drug delivery device

Claim 1

A controlled release drug delivery device comprising a composition of: (a) a polymer which swells upon exposure to an aqueous environment of use; (b) a plurality of controlled release swelling modulators selected from the group consisting of surfactants, osmagents and buffers dispersed throughout said polymer, each of which is either coated with a microporous coating or dispersed within an individual matrix, said controlled release swelling modulators regulating the swelling of said polymer, and hence the rate of release of beneficial agent from said drug delivery device, upon exposure of said device to an aqueous environment of use; (c) at least one beneficial agent; and (d) a member comprising (1) a water insoluble, apertured coating surrounding said composition and wherein the aperture may vary from 10 angstroms to the size of the tablet and wherein the coating is selected from the group consisting of cellulose esters, cellulose ethers, acylated polysaccharides, polyurethanes, polyacrylates, polymethacrylates, and poly(vinylchloride) of about 1 to 1000 microns thick or (2) a microporous wall surrounding said composition, said microporous wall consisting of a water insoluble coating containing water soluble leachable additives of organic or inorganic origin which form pores upon exposure of said wall to an aqueous environment of use.

Claim 8

A method of achieving continuous or intermittant release of a beneficial agent into an aqueous environment of use comprising: introducing a controlled release device according to claims 1 or 7 to said environment, said polymer swelling upon exposure to said aqueous environment, and thereby releasing beneficial agent, at a rate substantially determined by said controlled release swelling modulators.