The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jan. 08, 1991
Filed:
May. 22, 1989
Herman J Eichel, Columbus, OH (US);
Brent D Massmann, Columbus, OH (US);
Kinaform Technology, Inc., Dayton, OH (US);
Abstract
A sustained-release pharmaceutical preparation utilizing a pH controlled diffusion membrane composed of a pH sensitive film-forming polymer. The film forming polymer may be an enteric polymer containing phthalic acid with one carboxyl group attached to the enteric polymer via an ester bond, and the second carboxyl group remaining a free acid so that the modified film forming polymer is hydrophobic at low pH and hydrophilic at higher pH. Hydrophobic stearyl side chains are attached to the enteric polymer which causes the pH controlled diffusion membrane to remain insoluble at high pH. Alternatively, the pH sensitive film forming polymer may be a polymer containing hydrophobic and free acid groups so that the modified film forming polymer is hydrophobic at low pH and hydrophilic but insoluble at high pH. In the preferred sustained-release pharmaceutical preparation the film forming polymer is coated into core drug particles to produce a pH controlled diffusion membrane surrounding the core drug and form microparticles which may be admixed with free drug or time-release drug and placed in a gelatin capsule or tabletted.