Patent ID: 8309104

Claim:
A controlled release oral dosage form consisting of: (a) a unitary and homogeneous core comprising: (i) zolpidem tartrate; and (ii) about 3% to about 15% of a water soluble polymer that swells in the presence of water or gastro-intestinal fluids and exhibits a viscosity in a 2% aqueous solution of about 1,000 cps to about 120,000 cps; and (b) a pH dependent coating surrounding the homogeneous core comprising: (i) about 50% to about 80% by weight of the coating of an enteric polymer selected from the group consisting of zein, methacrylic acid copolymers, cellulose acetate phthalate, hydroxypropyl methylcellulose phthalate, hydroxypropyl methylcellulose acetate succinate, cellulose acetate trimellitate, polyvinyl acetate phthalate or mixtures thereof; and (ii) about 20% to about 50% by weight of the coating of a water soluble pore forming material selected from the group consisting of lactose, sucrose, fructose, mannitol, sorbitol, hydroxypropyl methylcellulose, hydroxypropyl cellulose, polyvinyl pyrrolidone, poloxamer, sodium lauryl sulfate, polysorbate, fumaric acid, succinic acid, citric acid, sodium chloride and potassium chloride; and (c) optionally an aesthetic coating surrounding the pH dependent coating; wherein all the zolpidem tartrate is present in the homogeneous core, the pH dependent coating comprises about 1 to about 20 weight percent of the dosage form and wherein the dosage form exhibits the following dissolution profile when tested in a USP apparatus 2, using 900 ml of 0.01 N HCl at 50 rpms and 37° C.: not more than 35% of the zolpidem is released within 0.5 hours; 30-75% of the zolpidem is released within 1 hour; not less than 45% of the zolpidem is released within 2 hours; and not less than 85% of the zolpidem is released within 8 hours.