Sustained release matrix pharmaceutical composition

1 . A sustained release pharmaceutical composition in solid dosage form comprising (a) a therapeutically effective amount of one or more active pharmaceutical ingredients; (b) a first high viscosity release retarding cellulose ether; and (c) a second high viscosity release retarding cellulose ether, wherein the first and second high viscosity release retarding cellulose ethers are of the same material.

2 . The composition of claim 1 , wherein the active pharmaceutical ingredient is selected from the group consisting of alprazolam, acetazolamide and mixtures thereof.

3 . The composition of claim 1 , wherein the first and second high viscosity release retarding cellulose ethers have a viscosity of greater than about 400 centipoise (cP).

4 . The composition of claim 1 , wherein the first and second high viscosity release retarding cellulose ethers have a viscosity of at least about 1500 cP.

5 . The composition of claim 1 , wherein the first and second high viscosity release retarding cellulose ethers have a viscosity of at least about 4000 cP.

6 . The composition of claim 1 , wherein the first high viscosity release retarding cellulose ether has a viscosity greater than or equal to about 1000 cP and the second high viscosity release retarding cellulose ether has a viscosity greater than or equal to about 5000 cP.

7 . The composition of claim 1 , wherein the first high viscosity release retarding cellulose ether has a viscosity greater than or equal to about 3500 cP and the second high viscosity release retarding cellulose ether has a viscosity greater than or equal to about 10,000 cP.

8 . The composition of claim 1 , wherein the first high viscosity release retarding cellulose ether has a viscosity greater than or equal to about 4000 cP and the second high viscosity release retarding cellulose ether has a viscosity greater than or equal to about 15,000 cP.

9 . The composition of claim 1 , wherein the first and second high viscosity release retarding cellulose ethers are selected from the group consisting of a hydroxypropyl methylcellulose (HPMC) polymer, hydroxypropyl cellulose (HPC) polymer, hydroxyethyl cellulose (HEC) polymer and mixtures thereof.

10 . The composition of claim 1 , wherein the first and second high viscosity release retarding cellulose ethers are a HPMC polymer.

11 . The composition of claim 10 , wherein the first and second high viscosity HPMC are of a type selected from the group consisting of 2208, 2906 and 2910.

12 . The composition of claim 10 , wherein the first high viscosity HPMC is of type 2208 and the second high viscosity HPMC is of type 2910.

13 . The composition of claim 10 , wherein the first high viscosity HPMC is of type 2208 and the second high viscosity HPMC is of type 2910 and the viscosity of the first and second high viscosity HPMC is the same.

14 . The composition of claim 10 , wherein the first high viscosity HPMC is of type 2208 and the second high viscosity HPMC is of type 2910 and the viscosity of the first and second high viscosity HPMC is different.

15 . The composition of claim 1 , wherein the first high viscosity release retarding cellulose ether is HPMC of type 2208 and the second high viscosity release retarding cellulose ether is HPMC of type 2910 and the viscosity of the first and second high viscosity HPMC is the same.

16 . The composition of claim 1 , wherein the amount of the first high viscosity release retarding cellulose ether is about 15 to about 35 weight percent and the amount of the second high viscosity release retarding cellulose ether is about 5 to about 20 weight percent.

17 . The composition of claim 1 , further comprising one or more pharmaceutically acceptable excipients.

18 . The composition of claim 1 , in the form of a tablet.

19 . The composition of claim 18 , having a total tablet weight of about 200 mg to about 500 mg.

20 . A method of treating a CNS condition or disorder in a subject, the method comprising orally administering to the subject a therapeutically effective amount of the composition of claim 1.