Evaluation of the film-coating properties of a hydroxyethyl cellulose/hydroxypropyl methylcellulose polymer system

The effect of different grades of hydroxyethyl cellulose (HEC) and hydroxypropyl methylcellulose (HPMC) on the film-formation and taste-masking ability for ibuprofen granules was evaluated. Three batches of coated ibilprofen granules were prepared using a roto-granulator, each with a different coating composition. Two grades of HEC [MW 300,000 (H) and MW 90,000 (L)] were combined with three different grades of HPMC [MW 11,000 (L), MW 25,000 (M) and AMW 35,000 (H)] to prepare the coating solutions. Mechanical strength and physical properties of the polymer films were evaluated. Films made from HPMC (L)\ HEC (H), HPMC (M)/HEC (H), and HPMC (H)/HEC (H) were stronger and more flexible than the HPMC (L) /HEC (L) films. The assay, dissolution, particle size distribution, and environmental scanning electron microscopy (ESEM) data of the three batches of the coated ibuprofen granules were similar. These data indicated that the two grades of HEC had equivalent film-coating properties. However, the HPMC (L)/HEC (L) film-coated granules showed better taste-masking characteristics (no burning after-taste) than the HPMC (L)/HEC (H) and HPMC (M)/HEC (H) film-coated granules. The ESEM data of the polymer films indicated that both HPMC (L)/HEC (H) and HPMC (M)/HEC (H) films exhibited more roughness and contained larger particles than the HPMC (L)/HEC (L) films. A study of the films revealed that HPMC (L)/HEC (H) and HPMC (M)/HEC (H) films were more susceptible to moisture effects, which subsequently led to a faster hydration rate of the polymer films. These data suggest that the molecular weight of the HEC affects the taste-masking ability, of the resultant polymer film. The HEC (L) mixed well with the HPMC (L) to yield a uniform film that was more resistant to moisture effects. Hence for optimum coating applications, particular attention should be paid to the molecular weight of the coating polymers to ensure that they are comparable to each other.