Polymeric coating materials have been widely used to modify release rate of
drug. We compared physical properties and release-controlling efficiency of polymeric coating materials using matrix-type casted film and diffusion-controlled coated
tablet. Hydroxypropylmethyl
cellulose (HPMC) with low or high viscosity grade, ethylcellulose (EC) and
Eudragit(R) RS100 as pH-independent
polymers and
Eudragit S100 for enteric coatings were chosen to prepare the casted film and coated
tablet. Tensile strength and contact angle of matrix-type casted film were invariably in the decreasing order: EC>
Eudragit S100> HPMC 100000>
Eudragit RS100>HPMC 4000. There was a strong linear correlation between tensile strength and contact angle of the casted films. In contrast,
weight loss (film solubility) of the matrix-type casted films in three release media (gastric, intestinal fluid and water) was invariably in the increasing order: EC < HPMC 100000 <
Eudragit RS100 < HPMC 4000 with an exception of
Eudragit S100. The order of release rate of matrix-type casted films was EC > HPMC 100000 >
Eudragit RS100 > HPMC 4000 >
Eudragit S100. Interestingly, diffusion-controlled coated
tablet also followed this rank order except
Eudragit S100 although release profiles and lag time were highly dependent on the coating levels and type of polymeric coating materials. EC and
Eudragit RS100 produced sustained release while HPMC and
Eudragit S100 produced pulsed release. No molecular interactions occurred between
drug and coating materials using (1)H-NMR analysis. The current information on release-controlling power of five different coating materials as matrix carrier or diffusion-controlled film could be applicable in designing oral sustained
drug delivery.