Abstract: Disclosed is a controlled release dosage form comprising a therapeutically effective amount of a pharmaceutically active agent, which may be Acyclovir, that releases in about 12 hours 80-100% of the active agent in a simulated gastric juice in a first order rate of release in a USP type 2 dissolution test, and not containing a solubilizer or a swelling enhancer or both, containing (a) a tablet made from polymer matrix of at least two biocompatible polymers, which may be Carbopol 974P and polyethylene oxide, the pharmaceutically active agent and pharmaceutically permitted excipients; the tablet capable of rapid swelling without disintegration in the simulated gastric juice to a size that results in its gastric retention in the stomach and start controlled release of the active agent by starting controlled erosion as well as diffusion immediately after coming into contact with the gastric juice.

Abstract: Controlled release dosage forms comprising a pharmaceutically active agent capable of not more than 90% release in 12 hours in a simulated gastric juice in first order release rate USP type 1 dissolution test, comprising (a) a tablet made from polymer matrix of at least two biocompatible polymers, the pharmaceutically active agent and excipients; the tablet capable of rapid swelling without disintegration in simulated gastric juice to a size resulting in gastric retention in the stomach and controlled release of the active agent by controlled erosion and diffusion immediately after coming into contact with the gastric juice, or (b) microspheres of ungrafted chitosan or a chitosan derivative or CARBOPOL® incorporating the active agent which is not a polymeric molecule and after administration in stomach, the microspheres adhere to the gastric mucosa for a long and controlled time release of the active agent.

Abstract: The invention discloses a controlled release dosage form comprising a therapeutically effective amount of a pharmaceutically active agent, illustrated by Acyclovir, that would release in about 12 hours not more than about 90% of the said active agent in a simulated gastric juice in a first order rate of release in a USP type 1 dissolution test, and not containing a solubilizer or a swelling enhancer or both, comprising (a) a tablet made from polymer matrix of at least two biocompatible polymers, illustrated by Carbopol 974P and polyethylene oxide, the said pharmaceutically active agent and pharmaceutically permitted excipients; the said tablet capable of rapid swelling without disintegration in the said simulated gastric juice to a size that shall result in its gastric retention in the stomach and start controlled release of the said active agent by starting controlled erosion as well as diffusion immediately after coming into contact with the said gastric juice, or (b) microspheres of ungrafted chitosan or a