Department of Polymer Science & Technology, University of Calcutta, 92 A.P.C. Road, Kolkata 700 009, India.
Int J Biol Macromol. 2012 Apr 1;50(3):565-72. doi: 10.1016/j.ijbiomac.2012.01.025. Epub 2012 Jan 24.
The effect of molecular weight of poly(vinyl alcohol) (PVA) and sodium chloride on the gelation temperature of methylcellulose (MC) was studied with the objective to develop a MC based formulation for sustained delivery of ketorolac tromethamine a model ophthalmic drug. Pure MC showed sol-gel transition at 61.2 °C. In order to reduce the gelation temperature of MC and to increase the drug release time, PVA was used. Different techniques such as test tube tilting method, UV-vis spectroscopy, viscometry and rheometry were used to measure gelation temperature of all the binary combinations of MC and PVA. It was observed that the gelation temperature of MC was reduced with the addition of 4% PVA and also the extent of reduction of the gelation temperature of MC was dependent on the molecular weight of PVA. The strong interactions between MC and PVA molecules were established using Fourier transform infrared spectroscopy. To study the in vitro drug release properties of the MC-PVA binary combinations, 6% sodium chloride was used to reduce the gelation temperature further up to physiological temperature. It was observed that the drug release time increased from 5 to 8h with the increase of molecular weight of PVA from 9×10(3) to 1.3×10(5) and this was due to the higher viscosity, better gel strength and greater interactions between the drug and PVA molecules in case of PVA (1.3×10(5)) compared to PVA (9×10(3)). In order to have an idea about the nature of interactions between the functional moieties of the drug and the polymer unit of PVA, a theoretical study was carried out.
研究了聚（乙烯醇）（PVA）和氯化钠的分子量对甲基纤维素（MC）胶凝温度的影响，目的是开发一种基于 MC 的制剂，用于持续输送酮咯酸氨丁三醇（一种模型眼科药物）。纯 MC 在 61.2°C 表现出溶胶-凝胶转变。为了降低 MC 的胶凝温度并延长药物释放时间，使用了 PVA。使用了不同的技术，如试管倾斜法、紫外-可见光谱法、粘度法和流变学法，来测量 MC 和 PVA 的所有二元组合的胶凝温度。结果表明，随着 4%PVA 的加入，MC 的胶凝温度降低，并且 MC 的胶凝温度降低程度取决于 PVA 的分子量。使用傅里叶变换红外光谱法证实了 MC 和 PVA 分子之间的强相互作用。为了研究 MC-PVA 二元组合的体外药物释放特性，使用 6%氯化钠进一步将胶凝温度降低至生理温度。结果表明，随着 PVA 分子量从 9×10(3)增加到 1.3×10(5)，药物释放时间从 5 小时增加到 8 小时，这是由于在 PVA（1.3×10(5)）的情况下，药物与 PVA 分子之间的相互作用更强，因此粘度更高、凝胶强度更好。为了了解药物的官能团与 PVA 聚合物单元之间相互作用的性质，进行了理论研究。
