Improvement of solubility and oral bioavailability of a poorly water-soluble drug, TAS-301, by its melt-adsorption on a porous calcium silicate.

The aim of the present study was to improve the solubility and oral bioavailability of a poorly water-soluble drug, 3-bis(4-methoxyphenyl) methylene-2-indolinone (TAS-301), by its melt-adsorption on a porous calcium silicate, Florite RE (FLR), without any solvents. The melt-adsorbed products were prepared by two methods: the small-scale batch method and the twin screw extruder method. The drug was melted and adsorbed on FLR (i.e., "melt-adsorption"), above its melting point. Crystallinity of the drug in the melt-adsorbed product was estimated by differential scanning calorimetry (DSC) and powder X-ray diffraction analysis. The dissolution test was conducted by the JP XIII paddle method. Oral absorption of the melt-adsorbed product was studied in fasted and fed dogs. The melt-adsorbed products prepared by the two methods were in powder forms. The drug existed in an amorphous state in the product and hardly recrystallized even after storing at a stressed condition (60 degrees C/80% RH for 3 days). The TAS-301 dissolution rate from the melt-adsorbed product was markedly enhanced compared with drug crystals. The area under the plasma concentration-time curve (AUC) and peak concentration (C(max)) values of the drug after dosing the melt-adsorbed product were significantly greater than those after dosing the drug crystals. The solubility and bioavailability of TAS-301 were improved by its melt-adsorption on FLR. The present findings suggest melt-adsorption is a useful technique for improving solubility and bioavailability of poorly water-soluble drugs. Copyright 2002 Wiley-Liss, Inc. and the American Pharmaceutical Association J Pharm Sci 91:362-370, 2002