Patent ID: 6720004
Filing Date: 2004-04-13
Classification: A61K

Abstract:
An oral hydrophilic matrix formulation suitable for once-a-day administration comprising:a. from about 40 to about 80 w/w % of divalproex sodium and; b. said divalproex sodium is in admixture with about 20 to about 50 w/w % of a pharmaceutically acceptable polymer selected from the group consisting of polyvinylpyrolidine, hydroxypropyl cellulose, hydroxypropylmethyl cellulose, methyl cellulose, vinyl acetate copolymers, polysaccharides, polyethyleine oxide, methacrylic acid copolymers, and maleic anhydride/methyl vinyl ether copolymers; c. said formulation exhibits the following in-vitro dissolution profile, when measured in a type 2 dissolution apparatus (paddle) at 100 rpm, at a temperature of 37Â±0.5 C, in 500 ml of 0.1N HCl for 45 minutes, followed by 900 ml of 0.05 M phosphate buffer containing 75 mM sodium laurel sulfate (pH5.5) for the remainder of the testing period: i. from about 15% to about 27% of total valproate is released after 3 hours of measurement in said apparatus; ii. from about 44% to about 69% of total valproate is released after 9 hours of measurement in said apparatus; iii. from about 59% to about 90% of total valproate is released after 12 hours of measurement in said apparatus, and; iv. not less than 88% of total valproate is released after 18 hours of measurement in said apparatus.