Gastric-retentive oral drug dosage forms for controlled release of highly soluble drugs

The invention relates to medicaments freely or very readily soluble in water, and are produced in unit dosage form by incorporating into hydrophilic polymers consisting of a high molecular weight which swell when water embedded polymeric matrices. The dosage form may be a single tablet or two or three tablets retained in a capsule of gelatin only. This oral formulation is intended to be retained in the stomach and regulated manner diffuses the medicament containing the gastric cavity. With this method of administration, the drug is released from the matrix in gastric fluid by solution-diffusion. Once it reaches a sufficient size, the swollen polymeric matrix remains in the gastric cavity for several hours if the drug has been administered to the patient while nourishes, and remains long enough to allow a substantially complete release of the drug before it produces a significant erosion of the matrix. The swellable matrix reduces gastric fluid access to the drug thus limits the release rate of the drug. This procedure together with the delay spread by the selection of the specific polymers and polymer molecular weights give other variables result cone speed controlled sustained drug release in the gastric environment.