Ground mixtures containing 2-oxo-3-[4-(1-oxo-2-isoindolinyl) phenyl] butanamide (OIB) were prepared from synthetic high molecular compounds, celluloses, sugars, peptides and amino acids in order to improve dissolution and absorption characteristics of OIB, and the physicochemical properties and the gastrointestinal absorption of these various ground mixtures were compared. Endothermic heat due to the fusion of OIB on differential scanning calorimetry disappeared in some of the ground mixtures of OIB-additives (1 : 9), and X-ray diffraction of the ground mixture indicated that OIB was an amorphous form. The dissolution rates of all of the ground mixtures were found to be faster than that of OIB alone, but differences in dissolution rates were observed by the kind of additive. The ground mixtures with peptides, such as gelatin (GEL) and lysozyme, showed the highest dissolution rate. The absorption of OIB alone and of four ground mixtures containing GEL, polyvinylpyrrolidone, methyl cellulose and microcrystalline cellulose were investigated in dogs. The serum concentration of OIB was enhanced more markedly than that of drug alone, and especially, the ground mixture with GEL increased 15-fold with respect to the amount of OIB absorbed.
