Giordano F, Gazzaniga A, Moyano J R, Ventura P, Zanol M, Peveri T, Carima L
Dipartimento Farmaceutico, University of Parma, Italy.
J Pharm Sci. 1998 Mar;87(3):333-7. doi: 10.1021/js970256b.
This study investigates the polymorphism of piroxicam ester with pivalic acid. Two crystal modifications were prepared by recrystallization from toluene (form 1) and ethyl acetate (form 2). Data regarding preparation conditions, solid state properties, and physicochemical characterization of two polymorphs by means of FT/IR spectroscopy, X-ray diffractometry on powder, and thermal analysis are reported. Heat of fusion rule and thermodynamic formulas consistently indicate an enantiotropic stability relationship of forms 1 and 2 with a calculated transition point (32 degrees C) near the ambient temperature. The phase diagrams of each polymorph with piroxicam were also investigated in order to gain information about the thermal behavior of their solid mixtures. Liquidus curves calculated by the Schröder-Van Laar equation from fusion enthalpies and temperatures were found to agree satisfactorily with experimental results obtained by first heating runs with differential scanning calorimetry.
本研究考察了吡罗昔康与新戊酸酯的多晶型现象。通过从甲苯中重结晶（晶型1）和从乙酸乙酯中重结晶（晶型2）制备了两种晶体变体。报告了关于两种多晶型物的制备条件、固态性质以及通过傅里叶变换红外光谱、粉末X射线衍射和热分析进行的物理化学表征的数据。熔化热规则和热力学公式一致表明晶型1和晶型2之间存在对映体稳定性关系，计算得出的转变点（32℃）接近环境温度。还研究了每种多晶型物与吡罗昔康的相图，以获取有关其固体混合物热行为的信息。发现通过施罗德 - 范拉尔方程根据熔化焓和温度计算得到的液相线曲线与通过差示扫描量热法首次升温运行获得的实验结果令人满意地吻合。
