Patent ID: 8486448

Claim:
A solid, compressed controlled release formulation, comprising: (a) a core comprising a superabsorbent material selected from the group consisting of an acrylic acid polymer cross-linked with divinyl glycol, an acrylic acid polymer cross-linked with allyl ethers of pentaerythritol, and a mixture thereof, the superabsorbent material comprising from 30% to 70% (w/w) of the core; (b) a controlled release coat surrounding the core; and (c) a plurality of controlled release microparticles having a pharmaceutically active agent disposed therein, wherein the microparticles are disposed within the core, the coat, or both the core and the coat, the formulation having a hardness from about 200 N to about 400 N, and wherein the formulation (i) when intact and exposed to an aqueous medium, the pharmaceutically active agent is released from the formulation over a prolonged period of time, (ii) when crushed to break the controlled release coat and expose the core, and exposed to a volume of an aqueous medium that weighs 30 times the weight of the superabsorbent material in the formulation, the formulation absorbs all of the aqueous medium and swells to create a hard gel that traps the microparticles, and the microparticles provide controlled release of the pharmaceutically active agent, and (iii) when broken and exposed to 900 mL of water in a U.S.P. Type I Apparatus with stirring at 100 rpm for 30 minutes at 37° C., less than about 50% by weight of the pharmaceutically active agent originally present in the formulation before it was broken is released into the water.