ABSTRACT
Today, compressed hydrophilic matrices have become most popular as modified release dosage forms for oral administration. Among the swellable polymers used to prolong drug release, cel lulose ethers, in particular hydroxypropylmethylcellulose (HPMC), provoked considerable in terest because most display good compression characteristics, including when directly com pressed, and have adequate swelling properties that allow rapid formation of an external gel layer controlling drug release. They are available in several substitution and viscosity (molecu lar mass) grades and are well characterized in compendia. Furthermore, most of them have U.S. GRAS status (Generally Recognized As Safe) (1-6).
