Osmotic device containing amantadine and an osmotic salt

An osmotic device comprising a unitary core surrounded by a semipermeable membrane having at least one passageway there through, wherein:

• a) the unitary core comprises a mixture of amantadine salt, osmotic salt, and at least one other pharmaceutically acceptable excipient, and the weight ratio of amantadine salt to osmotic salt ranges from 2:1 to 30:1;
• b) the osmotic salt is not coated with a release rate controlling coating;
• c) the permeability of the semipermeable membrane is adapted to cooperate with the osmotic salt to control the release profile of amantadine salt from the osmotic device;
• d) the amantadine salt and osmotic salt have an ion in common;
• e) amantadine salt is released through the one or more passageways according to a sigmoidal controlled release profile, optionally wherein release of amantadine salt is delayed for a period of time, when the osmotic device is exposed to an aqueous environment of use;
• f) the semipermeable membrane comprises a cellulose acetate grade 1 and a cellulose acetate grade 2, wherein the weight ratio of a cellulose acetate grade 1 to the total amount of cellulose acetates ranges from 0:1 to 1:1, wherein the cellulose acetate grade 1 comprises 7-10% by wt. of hydroxyl groups, 30-36% by wt. of acetyl groups and a viscosity of 200-280 seconds, and cellulose acetate grade 2 comprises 3-5% by weight of hydroxyl groups, 37-43% by wt. of acetyl groups and a viscosity of 6.0-45.0 seconds;
• and
• g) the osmotic device further comprises a drug-containing coat comprising an active ingredient, wherein the coat is external to the semipermeable membrane.