Preparation of Novel Functional Drug Particles Embedded in a Gelling-Swelling Layer (PEGS) for Taste Masking and Subsequent Rapid Drug Release.

The purpose of this research was to develop novel functional drug particles embedded in a gelling-swelling layer (PEGS) which are capable of achieving both taste-masking of unpalatable drugs and rapid drug elution. The functional particles had a three-layer structure consisting of a core drug layer, a gelling-swelling layer and an outer water-penetration control layer containing a water-insoluble polymer. The concept of formulation design was as follows: when water reaches the gelling-swelling layer, pulverized fine gelling-swelling particles gellate and swell from water absorption to form a rigid layer, thereby preventing drug release. After a defined lag time, the increased volume of the gelling-swelling layer breaks down the outer water-penetration control layer, leading to rapid drug release. In order to adapt this system for use in orally disintegrating tablets, PEGS were prepared at a size of about 250 µm using a fine particle-coating method. Ambroxol hydrochloride was used as a model drug for bitterness and the effects of different gelling-swelling agents and water-insoluble polymers on drug release characteristics from PEGS were examined. In in vitro dissolution tests, it was shown that the drug dissolution rate from PEGS could be suppressed to about 5% after 2 min and increased to more than 85% after 30 min by adjusting the composition and thickness of the outer layer. The PEGS expanded about 1.5-fold and the outer layer was ruptured after 5 min in water.