Kollidon SR is a blend of 80 percent polyvinyl acetate and 19 percent povidone along with small quantities of sodium lauryl sulfate and silica, used as stabilizers.

Due to its combination of the very plastic polyvinyl acetate and strongly binding povidone, Kollidon SR has excellent compressibility and endows tablets with enormous hardness and low friability. When tablets formulated with this product 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 resulting in sustained action.