Patent ID: 8221792

Claim:
A sustained release matrix pharmaceutical composition, wherein the composition is in the form of an orally deliverable tablet, said composition prepared by the steps comprising: (i) micronizing a pharmaceutically active agent, wherein said pharmaceutically active ingredient is tramadol hydrochloride, which is freely soluble in water, wherein the pharmaceutically active agent is micronized to a particle size having an upper size limit of about or less than 125 micron (120 mesh) and a lower size limit of about or greater than 74 micron (200 mesh); (ii) combining said pharmaceutically active ingredient and a hydrophilic polymer, wherein said hydrophilic polymer is hydroxypropyl methylcellulose at 22.4% w/w; (iii) dry blending the micronized pharmaceutically active agent and said hydrophilic polymer to form a powder blend; and admixing the powder blend with microcrystalline cellulose present at 15.6% w/w and magnesium stearate present at 2.0% w/w; (iv) compressing the powder blend into said sustained release matrix pharmaceutical composition in the form of a tablet comprising a layer of film using a coating composition comprising an aqueous dispersion containing ethyl cellulose, oleic acid, ammonium hydroxide and water and a solution containing polyethylene glycol.