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Li K.,Tianjin University | Du S.,Tianjin University | Wu S.,Tianjin University | Cai D.,Shijiazhuang Pharmaceutical Group Ou Yi Co. | And 8 more authors.
Journal of Chemical Thermodynamics | Year: 2016

In this paper, we proposed a static analysis method to experimentally determine the (solid + liquid) equilibrium of racemic oxiracetam in (methanol + water), (ethanol + water) and (isopropanol + water) binary solvents with alcohol mole fraction ranging from 0.30 to 0.90 at atmosphere pressure (p = 0.1 MPa). For the experiments, the temperatures range from (283.15 to 308.15) K. The results showed that the solubility of oxiracetam increased with the increasing temperature, while decreased with the increasing organic solvent fraction in all three tested binary solvent systems. The modified Apelblat model, the CNIBS/Redlich-Kister model, the combined version of Jouyban-Acree model and the NRTL model were employed to correlate the measured solubility values, respectively. Additionally, some of the thermodynamic properties which can help to evaluate its dissolution behavior were obtained based on the NRTL model. © 2015 Elsevier Ltd. All rights reserved. Source


Du S.,Tianjin University | Li K.,Tianjin University | Zhang Y.,Shijiazhuang Pharmaceutical Group Ou Yi Co. | Gao Z.,Shijiazhuang Pharmaceutical Group Ou Yi Co. | And 5 more authors.
Huagong Xuebao/CIESC Journal | Year: 2015

It is found that direct freeze-drying method is not applicable to oxiracetam because of long time and poor product quality. In this paper, MS software is used to calculate the molecular interactions between additive (sorbitol) and different crystal surfaces of oxiracetam. These values are very small and could be neglected. Experiments also show that the crystal form and morphology are independent of sorbitol in freeze-drying process. Analyzed by differential scanning calorimetry and hot-stage microscopy, glassy sate of oxiracetam prescription is identified during original prefreezing process, against sublimation of water molecules. Therefore, we propose a gradual congelation crystallization technology to change the crystal state of sorbitol, congeal every component and separate them in microcrystalline. According to results of larger scale experiments, this new technique greatly shortens the time required and improves the product quality. © All right reserved. Source

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