ABSTRACT
Sakae Obara and Hiroyasu Kokubo Cellulose and Pharmaceutical Excipients Department, Shin-Etsu Chemical Co., Ltd.,
INTRODUCTION
The first application of hypromellose, also known as hydroxypropyl methylcellulose (HPMC), for film coating appeared in a patent by Singiser (1) of Abbott Laboratories in 1962. Film coatings using HPMC have become popular, taking the place of the conventional sugar coating of tablets, because they give a superior appearance, act as protection for fragile tablets, and mask the unpleasant taste of drug substances. The main reason for the extensive use of HPMC as a film-coating polymer is that it is soluble in some organic solvents and also in water over the entire biological pH range. Film coating can therefore be done using an organic solvent system, and the film formed will dissolve in the digestive juices, leading to complete release of the active ingredients.
