Johnson F A, Craig D Q, Mercer A D
Centre for Materials Science, School of Pharmacy, London, UK.
J Pharm Pharmacol. 1997 Jul;49(7):639-43. doi: 10.1111/j.2042-7158.1997.tb06085.x.
Sodium alginates are widely used within the pharmaceutical sciences, yet the molecular characteristics of these materials are frequently not stated. In this study, a range of characterization techniques is applied to five sodium alginate samples and the data compared, both between techniques and with the information obtained from the manufacturer. The mannuronic acid to guluronic acid (MG) ratio and the distribution of uronic acid residues of five sodium alginate samples have been measured using circular dichroism and NMR, with circular dichroism yielding MG ratios between 42.1 and 63.6%, depending on the grade of alginate used. The MG ratios obtained from NMR studies were in broad agreement with these values, and the technique also yielded information on the distribution of uronic acid residues within each batch; this was again found to vary considerably (NG > 1 values ranging from 6.9 to 17.5). It was noted that samples with similar MG ratios could have markedly different chain-distribution characteristics. The uronic acid ratio ranges obtained from the manufacturers were found to be in good agreement with those found experimentally. Intrinsic viscosity measurements were used to compare the molecular weights of the samples; values between approximately 12,000 and 180,000 were obtained for the different batches. The study has enabled comparison of different methods for characterization of sodium alginate samples, highlighting their relative merits and the possible protocols that might be adopted. A critical discussion is given of the individual and combined use of these techniques and the relevance of such studies to the rational design and quality control of alginate-based pharmaceutical systems.
海藻酸钠在制药科学中被广泛应用，然而这些材料的分子特性却常常未被阐明。在本研究中，一系列表征技术被应用于五个海藻酸钠样品，并对数据进行了比较，包括不同技术之间的比较以及与从制造商处获得的信息的比较。使用圆二色性和核磁共振测量了五个海藻酸钠样品的甘露糖醛酸与古洛糖醛酸（MG）比率以及糖醛酸残基的分布，根据所使用海藻酸盐的等级，圆二色性得出的MG比率在42.1%至63.6%之间。从核磁共振研究中获得的MG比率与这些值大致相符，该技术还提供了每批样品中糖醛酸残基分布的信息；再次发现其差异相当大（NG>1值范围为6.9至17.5）。值得注意的是，具有相似MG比率的样品可能具有明显不同的链分布特征。发现从制造商处获得的糖醛酸比率范围与实验发现的结果高度一致。使用特性粘度测量来比较样品的分子量；不同批次获得的值在约12,000至180,000之间。该研究使得能够比较表征海藻酸钠样品的不同方法，突出了它们的相对优点以及可能采用的方案。对这些技术的单独和联合使用以及此类研究与基于海藻酸盐的药物系统的合理设计和质量控制的相关性进行了批判性讨论。
