Patent ID: 7736667

Claim:
A controlled-release oral drug dosage form for releasing a drug into at least a portion of a region defined by the stomach and the upper gastrointestinal tract, said dosage form comprising: (a) a core comprising a first solid polymeric matrix with said drug dispersed therein, and (b) a shell encasing said core, said shell comprising a second solid polymeric matrix that swells upon imbibition of water to a size large enough to promote retention in the stomach while the stomach is in a fed mode, and said shell having a drug:polymer weight ratio that is less than that of said core, said shell having a thickness that is at least about 0.5% of the longest linear dimension of said dosage form, said second polymeric matrix being of a material and thickness relative to said core such that when said dosage form is immersed in gastric fluid, said drug is released from said dosage form into said gastric fluid at a controlled rate by diffusion of said drug through said shell during substantially the entire period of drug release such that at least about 40% of said drug remains unreleased one hour after such immersion has begun and substantially all of said drug is released within about twenty-four hours after such immersion has begun, said shell remaining intact during substantially the entire period of drug release, wherein said first solid polymeric matrix and said second polymeric matrix comprise a polymer independently selected from the group consisting of a poly(ethylene oxide), a cross-linked polyacrylic acid, and a hydroxyalkyl-substituted cellulose.