Characterization of Core Particles for Film Coating with High Active Ingredient Content

Abstract

The object of this study was to prepare high drug content core particles that are suitable for the coating process. Ethenzamide (ETZ) of fine grade (mean median diameter 7.3 μm) was used as a model drug, and core particles before layering (core particles-N) were prepared by using an agitating fluidized bed granulator. To obtain core particles with a smooth surface, layering was carried out by spraying the core particles-N with a suspension of ultrafine grade (mean median diameter 2.8 μm) ETZ in the binder (hydroxypropylcellulose) solution. The size distribution, tensile strength, and bulk density of the core particles-N and core particles after layering (core particles-L) were measured, and surface shape of each particle was observed. To further evaluate the smoothness of the obtained core particles-N and core particles-L, coating was performed by using hydroxypropylmethylcellulose (HPMC)-base Opadry^® and ethylcellulose (EC)-base Aquacoat^® and dissolution test was carried out. The dissolution of ETZ from the coated core particles-L was less than from core particles-N even though the amount of the coating agent used was the same; this resulted from the core particles-L being coated more evenly because of their smoother surfaces. Thus a method to obtain high drug content core particles that can be coated with less coating agent was established.