Institute of Pharmaceutical Sciences, Department of Pharmaceutical Technology, University of Graz, 8010 Graz, Austria.
Soft Matter. 2019 Feb 20;15(8):1853-1859. doi: 10.1039/c8sm02529k.
Control over drug delivery may be interestingly achieved by using temperature responsive encapsulants, which change their thickness and mesh size with temperature. The prototype N-isopropylacrylamide hydrogel cross-linked with di(ethylene glycol) divinyl ether p(NIPAAm-co-DEGDVE) swells at low temperature and collapses above the lower critical solution temperature (LCST), ∼29 °C in a buffer. It might be expected that drug release from such encapsulation is always favored below the LCST, due to the larger free volume present in the swollen polymer film. Recent results show contradicting behavior where some cases behave as expected and others release much less when the polymer layer is swollen. In this study, layers of the drugs phenytoin, clotrimazole and indomethacin were drop cast on glass and p(NIPAAM-co-DEGDVE) layers were then synthesized directly on top of these drug layers via initiated chemical vapor deposition (iCVD), a solvent-free and gentle polymerization technique. Dissolution experiments were then performed, in which the drug release through the hindrance of the hydrogel was measured at different pH values. The results show that not only the swelling but also the permeate (drug in this case)-polymer interaction plays an important role in the release.
通过使用温度响应性封装剂可以有趣地实现对药物输送的控制，这些封装剂的厚度和网格尺寸随温度而变化。原型 N-异丙基丙烯酰胺水凝胶与二（乙二醇）二乙烯基醚交联（p（NIPAAm-co-DEGDVE））在低温下溶胀，并在低于低临界溶液温度（LCST），约 29°C 的缓冲液中坍塌。可以预期，由于溶胀聚合物膜中存在更大的自由体积，因此药物释放总是有利于低于 LCST 的温度。最近的结果显示出矛盾的行为，在某些情况下，聚合物层溶胀时，药物的释放情况与预期相反，而在其他情况下则释放较少。在这项研究中，将苯妥英、克霉唑和吲哚美辛等药物的层滴铸在玻璃上，然后通过引发化学气相沉积（iCVD）直接在这些药物层上合成 p（NIPAAM-co-DEGDVE）层，这是一种无溶剂且温和的聚合技术。然后进行溶解实验，在不同的 pH 值下测量药物通过水凝胶的阻碍释放。结果表明，不仅溶胀，而且渗透物（在这种情况下是药物）-聚合物相互作用在释放中起着重要作用。
