| 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 chitosan derivative illustrated by thiolated chitosan and trimethyl chitosan, or Carbopol incorporating the said active agent, wherein the said pharmaceutically active agent is not a polymeric molecule and after administration in stomach, the said microspheres adhare to the gastric mucosa for a long time releasing the active agent in a controlled way. |