Effects of Grinding on the Physical and Chemical Properties of Crystalline Medicinals with Microcrystalline Cellulose V : Comparison with Tri-O-methyl-β-cyclodextrin Ground Mixtures

Abstract

Ground mixtures of aspirin, benzoic acid and p-acetoxydiphenyl were prepared with tri-O-methyl-β-cyclodextrin (methyl-CD). An apparent amorphous state of methyl-CD and the medicinals after grinding was indicated by X-ray diffraction analysis. Infrared analysis also indicated that the medicinal molecules were monomolecularly dispersed in the methyl-CD ground mixtures. The infrared solution spectra of medicinals in CCl₄ were compared with the solid state infrared spectra in the carbonyl stretching absorption region. It was found that in the ground mixture of aspirin with methyl-CD, the hydroxyl group of aspirin was hydrogen-bonded with the methoxyl group of methyl-CD, while the acetoxyl group of aspirin was in a free state.