Abstract
The effect of grinding in an agate cetrifugal ball mill on the physicochemical properties of form A of chloramphenicol palmitate (CPP) was studied by means of X-ray diffractometry, differential scanning calorimetry (DSC) and infrared (IR) spectrophotometry.
The peak intensities of X-ray diffraction profiles of form A decreased with increasing grinding time, and a part of form A converted to a noncrystalline solid. The crystallinity of form A ground for 1-10h was about 50% by means of Hermans' method.
The melting point and heat of fusion of form A ground for 1-10h decreased about 3°C and about 11.2kJmol-1, respectively, compared with those of intact form A. The solubility of form A ground for 10h was about twice higher than that of the intact form A.
The IR spectra of ground form A suggested that the amputation of the intermolecular hydrogen bond between the carbonyl group of the amido and the hydroxyl group in the crystal structure of form A was caused by mechanical stress during grinding, and that form A converted to a noncrystalline state.
