Kollidon SR is a blend of polyvinyl acetate and povidone for use as a matrix-forming agent in directly compressible sustained –release tablets.  It consists of 80% polyvinyl acetate and 19% povidone alongwith small quantities of sodium lauryl sulfate and silica as stabilizers.

Polyvinyl acetate is a very plastic material that produces a coherent matrix under low compression forces.  When the tablets formulated using Kollidon SR are introduced into gastric or intestinal fluid, the water soluble povidone is leached out to form pores through which the active ingredient slowly diffuses out through these pores to give sustained action.  Kollidon SR contains no ionic groups and is therefore inert to drug substances. The sustained-release properties are unaffected by ions or salts.