Hydrogel-driven drug dosage form

1. A controlled release drug dosage form comprising a core and a coating around said core, said coating consisting of a mixture of cellulose acetate and polyethylene glycol, wherein said core comprises a drug-containing composition and a water-swellable composition, each occupying separate regions within said core and wherein

(a) said drug-containing composition comprises a drug, the drug-entraining agent polyethylene oxide, and the fluidizing agent selected from the group consisting of sugars and organic acids; and

(b) said coating is water-permeable, water-insoluble, has at least one delivery port therethrough, and a durability of at least 1 Kp/cm 2 ; and wherein said coating is formed from a substantially homogeneous solution comprising a solvent, said cellulose acetate, said polyethylene glycol, and at least 4 wt % of the non-solvent water but not greater than a weight percent such that a cloud point of the solution is reached when the solution is at room temperature, wherein a weight ratio of cellulose acetate to polyethylene glycol of from 8:2 to 6.5:3.5.

2. The dosage form of claim 1 wherein said coating is formed from a solution containing at least 15 wt % water but not greater than a weight percent such that a cloud point of the solution is reached.

3. The dosage form of claim 1 , wherein said water swellable composition comprises polyethylene oxide, microcrystalline cellulose, and an osmagent selected from magnesium sulfate, magnesium chloride, calcium chloride, sodium chloride, lithium chloride, potassium sulfate, sodium carbonate, sodium sulfite, lithium sulfate, potassium chloride, sodium sulfate, d-mannitol, urea, sorbitol, inositol, raffinose, sucrose, glucose, fructose, lactose, and mixtures thereof.