Design of delayed-swellable spherical drug particles with taste-masking function for orally disintegrated (OD) tablet using mechanofusion coating and melt layering technique

Abstract

Novel bitter-taste-masking microparticles for loading in orally disintegrating (OD) tablets have been developed using a mechanical powder processor. Swellable ordered-mixed drug particles (Swell-OM-spheres, SOS), in which modified starch core particles are coated with pulverized drug crystals in an ordered mixture (OM) manner, were produced in our previous research.

The authors have demonstrated that SOS particles had improved dissolution behavior of poorly water-soluble drugs due to their swellable function in the aqueous phase. Therefore, we aimed to design taste-masking fine particles by overcoating the functional excipients around SOS particles using the same equipment. In the first step, a gelling agent (Gel) was overcoated on the surface of SOS particles to form a swellable layer. In the second step, a waxy agent (Wx) was further coated on the surface of the resultant particles to form a water-insoluble layer. Thus, the coated particles with a four-layer structure (core/drug/Gel/Wx), named coated SOS (C-SOS) were prepared using a single equipment in a completely dry process without any water or solvent.

The dissolution test revealed that C-SOS particles had a delayed booster release behavior. It is assumed that the outer insoluble layer of C-SOS particles would efficiently prevent the initial water penetration in aqueous medium, resulting in introducing a release lag time. Once water reaches the swellable gelling layer, the expansion of inner particles would burst the outer wax layer and begin rapid release of the drug, leading to sigmoidal release behavior with a short lag time. The present research realized the novel dry-powder coating technique for developing the microparticles with masked bitterness to be loaded in OD tablets.

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Chemicals

Sodium starch glycolate particles  (EX) (EXPLOTAB, Rettenmaier Japan Co., Ltd., Tokyo, Japan) were used as small spheres (beads) in the dry-milling process and as core particles in the dry-coating process. Phenytoin (PHT) (FUJIFILM Wako Pure Chemical Co., Ltd., Osaka, Japan) was used as the model drug substance. The purity and mean particle size of the intact phenytoin powder were > 99.9% (extra pure grade) and 9.97 μm, respectively. Carmellose sodium.

Toshiyuki Niwa, Keita Kondo, Haruka Makino, Honoka Itoh, Design of delayed-swellable spherical drug particles with taste-masking function for orally disintegrated (OD) tablet using mechanofusion coating and melt layering technique, European Journal of Pharmaceutics and Biopharmaceutics, Volume 226, 2026, 115125, ISSN 0939-6411, https://doi.org/10.1016/j.ejpb.2026.115125.

Read also our introduction article on Orally Disintegrating Tablets (ODTs) here: