Preformulation Studies on the S-Isomer of Oxybutynin Hydrochloride, an Improved Chemical Entity (ICE)

摘要

(S)-Oxybutynin HCl (S-OXY) is a white crystalline solid powder with an acicular particle morphology. Differential scanning calorimetry (DSC) thermograms revealed one characteristic endotherm at 116.2°C. Observation by hot-stage microscopy confirmed the melting endotherm observed by DSC. Equilibrium moisture uptake studies indicated low water vapor uptake at low relative humidities (_52.8%). At relative humidities of 75.3% and 84.3%, S-OXY first deliquesced and then converted to a lower melting point crystal form. X-ray powder diffraction (XRPD) data supported the DSC findings.The kinetics of this reaction were studied at 25°C in carbonate-bicarbonate buffers.