抄録
Mannitol particles have been designed as a main additive for oral disintegrating (OD) tablets by a spray freeze-drying technique. An aqueous solution of mannnitol was sprayed onto the surface of liquid nitrogen and the frozen droplets were freeze-dried to prepare the spherical porous particles. The resultant mannitol particles (SFD particles) were compressed under lower pressure to obtain a tablet with a high porosity of around 50%. It was found that the mechanical strength of the tablet significantly increased under short-time exposure to heating/humidification, holding its porous structure. As a result, tablets with satisfactory physical hardness (tensile strength ≥ 1.0 MPa) and rapid disintegration properties (disintegration time ≤ 30 s) could be prepared in the current manufacturing processes. The hardening phenomenon of the mannitol tablet was analyzed by X-ray powder diffractometry. The SFD particles and the resultant tablet from these particles were found to be composed of the a form of mannitol, which is a meta-stable crystalline form. Under stress conditions, the crystal form of mannitol was transformed into the stable b form within several hrs. This crystal transition promoted the solid-bridging between particles in the tablet, resulting in the strong compactness with high porosity. The porous structure accelerated the water penetration into the tablet, leading to the rapid disintegration behavior. The SFD mannitol particles developed in this research can be used as a direct tableting additive for OD tablets in the pharmaceutical industry.
