Department of Physical Chemistry, Faculty of Pharmacy, Medical University of Warsaw, Warsaw 02-097, Poland.
J Pharm Sci. 2012 May;101(5):1763-72. doi: 10.1002/jps.23062. Epub 2012 Feb 13.
(13) C cross-polarization magic-angle spinning nuclear magnetic resonance (CPMAS NMR) spectroscopy was applied to the identification and characterization of carvedilol (1-(9H-carbazol-4-yloxy)-3-[2-(2-methoxyphenoxy)-ethylamino]-propan-2-ol) in pharmaceutical preparations. Solid-state spectra (standard linewidth and lack of signal multiplicity) of carvedilol indicate that its physical form is the same (freebase form II); no other polymorphic forms were detected. The spectra of excipients, recorded under the same conditions, were helpful in their identification. The differences in chemical shifts for tablets I-VI are insignificant and suggest that there are no strong intermolecular drug-excipient interactions. The drugs from six manufacturers contained the same amount (25 mg) of the active substance per tablet; however, tablets differ in size and thus in the concentration of carvedilol. An attempt at quantitation of carvedilol in the dosage forms was made. The cross-polarization kinetics and other measurement parameters affecting the intensity and reproducibility of the spectra were determined. The results revealed a satisfying relationship between the composition of the tablets and the intensity of selected NMR signals. The (13) C CPMAS NMR technique was found to provide accurate quantification of drugs without any chemical preparation, as shown by the particular case of carvedilol's solid formulations.
（13）交叉极化魔角旋转核磁共振（CPMAS NMR）光谱法被应用于药物制剂中卡维地洛（1-（9H-咔唑-4-氧基）-3-[2-（2-甲氧基苯氧基）-乙氨基]-丙-2-醇）的鉴别和特性分析。卡维地洛的固态光谱（标准线宽和信号单一性缺失）表明其物理形态相同（游离碱形式 II）；未检测到其他多晶型形式。在相同条件下记录的赋形剂的光谱有助于其鉴定。片剂 I-VI 的化学位移差异不显著，表明没有强烈的分子间药物-赋形剂相互作用。来自六家制造商的药物每片含有相同数量（25 毫克）的活性物质；然而，片剂的大小不同，因此卡维地洛的浓度也不同。尝试对制剂中的卡维地洛进行定量。确定了影响光谱强度和重现性的交叉极化动力学和其他测量参数。结果表明，片剂的组成与选定 NMR 信号的强度之间存在令人满意的关系。（13）CPMAS NMR 技术被发现可以提供无需任何化学制备的药物的准确定量，卡维地洛的固体制剂就是一个特殊的例子。
