Department of Physical Chemistry and Biophysics, Wroclaw Medical University, Borowska 211A, 50-556 Wrocław, Poland.
Faculty of Chemistry, Wrocław University of Science and Technology, ul. Gdańska 7/9, 50-344 Wrocław, Poland.
Int J Mol Sci. 2022 Aug 6;23(15):8759. doi: 10.3390/ijms23158759.
(1) Background: Depending on the type of hydrophilic polymer used, different types of hydrogels may be chemically stable or may degrade and eventually disintegrate, or dissolve upon exposure to sunlight. Many over-the-counter medications are now stored with a limited control of temperature, humidity and lighting. Therefore, in this study, the photostability of a gel made of cross-linked polyacrylic acid (PA), methylcellulose (MC) and aristoflex (AV) was assessed, and the interaction between the polymers used and ascorbic acid and its ethylated derivative was investigated. (2) Methods: The samples were continuously irradiated at constant temperature for six hours. The stability of the substance incorporated into the gels was assessed using a UV-Vis spectrophotometer. FTIR-ATR infrared spectroscopy was used to measure changes during the exposure. (3) Results: Ascorbic acid completely decomposed between the first and second hours of illumination in all samples. The exception is the preparation based on polyacrylic acid with glycerol, in which the decomposition of ascorbic acid slowed down significantly. After six hours of irradiation, the ethylated ascorbic acid derivative decomposed in about 5% for the polyacrylic acid-based gels and aristoflex, and in the methylcellulose gel it decomposed to about 2%. In the case of ascorbic acid, the most stable formulation was a gel based on polyacrylic acid and polyacrylic acid with glycerol, and in the case of the ethyl derivative, a gel based on methylcellulose. (4) Conclusions: The experiment showed significant differences in the decomposition rate of both compounds, resulting from their photostability and the polymer used in the hydrogel.
(1) 背景：根据所使用的亲水聚合物的类型，不同类型的水凝胶可能具有化学稳定性，也可能降解并最终分解或在暴露于阳光下时溶解。现在许多非处方药的储存都受到温度、湿度和光照的有限控制。因此，在这项研究中，评估了由交联聚丙烯酸 (PA)、甲基纤维素 (MC) 和 aristoflex (AV) 制成的凝胶的光稳定性，并研究了所使用的聚合物与抗坏血酸及其乙基衍生物之间的相互作用。(2) 方法：将样品在恒定温度下连续照射六小时。使用紫外可见分光光度计评估掺入凝胶中的物质的稳定性。傅里叶变换衰减全反射红外光谱法 (FTIR-ATR) 用于测量暴露过程中的变化。(3) 结果：在所有样品中，抗坏血酸在光照的第一到第二个小时之间完全分解。聚丙烯酸与甘油的制备物是个例外，其中抗坏血酸的分解明显减慢。照射六小时后，乙基抗坏血酸衍生物在基于聚丙烯酸的凝胶和 aristoflex 中分解约 5%，在甲基纤维素凝胶中分解约 2%。在抗坏血酸的情况下，最稳定的配方是基于聚丙烯酸和聚丙烯酸与甘油的凝胶，而在乙基衍生物的情况下，最稳定的配方是基于甲基纤维素的凝胶。(4) 结论：实验表明，两种化合物的分解率存在显著差异，这是由于它们的光稳定性和水凝胶中使用的聚合物不同所致。
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