Neville G A, Hasan F B, Smith I C
J Pharm Sci. 1977 May;66(5):638-42. doi: 10.1002/jps.2600660508.
The presence of isopilocarpine, an epimer of pilocarpine, and of pilocarpinic acid, a hydrolytic degradation product of pilocarpine, was established and all three substances were assayed in various commercial ophthalmic formulations of pilocarpine hydrochloride by 13C-Fourier transform spectroscopy. Assay was based upon integrated intensities of selected resonances from any formulation calibrated against the intensity of tetramethylammonium bromide, used as a common external reference. The normalized intensities were then related to those of a reference solution of pilocarpine hydrochloride, thereby eliminating any factor arising from variability of 13C-relaxation times. The 13C-resonance for the N-methyl group, being common to all products, provides a convenient basis for the assay of the total alkaloid content whereas the C-8 resonances are best suited for assaying residual pilocarpine and its degradation products. This procedure, estimated as accurate to +/- 5%, constitutes the first comprehensive analytical method to differentiate between pilocarpine and its degradation products.
毛果芸香碱的差向异构体异毛果芸香碱以及毛果芸香碱的水解降解产物毛果芸香酸的存在得到了确认，并且通过13C-傅里叶变换光谱法对盐酸毛果芸香碱的各种商业眼科制剂中的这三种物质进行了测定。测定基于任何制剂中选定共振峰的积分强度，该强度相对于用作通用外部参考的溴化四甲基铵的强度进行校准。然后将归一化强度与盐酸毛果芸香碱参考溶液的强度相关联，从而消除了由13C弛豫时间变化引起的任何因素。所有产品共有的N-甲基的13C共振为总生物碱含量的测定提供了便利的基础，而C-8共振最适合于测定残留的毛果芸香碱及其降解产物。该方法估计准确度为±5%，是首个区分毛果芸香碱及其降解产物的综合分析方法。
