Rosa G D, Iommelli R, La Rotonda M I, Miro A, Quaglia F
Dipartimento di Chimica Farmaceutica e Tossicologica, Facoltà di Farmacia, Università degli Studi di Napoli Federico II - Via Domenico Montesano 49-80131 Napoli, Italy.
J Control Release. 2000 Nov 3;69(2):283-95. doi: 10.1016/s0168-3659(00)00315-1.
The aim of this work was to produce insulin-loaded microspheres allowing the preservation of peptide stability during both particle processing and insulin release. Our strategy was to combine the concepts of using surfactants to improve insulin stability while optimising overall microsphere characteristics such as size, morphology, peptide loading and release. Bovine insulin was encapsulated within poly(lactide-co-glycolide) (PLGA 50:50, Resomer RG504H) microspheres by the multiple emulsion-solvent evaporation technique. Microspheres were prepared by adding to the primary emulsion three non-ionic surfactants, poloxamer 188, polysorbate 20 and sorbitan monooleate 80, at different concentrations (1.5 and 3. 0% w/v). The presence of surfactants was found to decrease the mean diameter and to affect the morphology of the microspheres. Insulin encapsulation efficiency was reduced in the presence of surfactants and especially for sorbitan monooleate 80, in a concentration-dependent mode. The influence of the surfactants on the interactions between insulin and PLGA together with the primary emulsion stability were found to be the major determinants of insulin encapsulation. The release of insulin from microspheres was biphasic, showing an initial burst effect followed by a near zero-order release for all the batches prepared. The initial burst was related to the presence of insulin molecules located onto or near to the microsphere surface. In the presence of surfactants, a faster insulin release with respect to microspheres encapsulating insulin alone was observed. Insulin stability within microspheres after processing, storage and release was evaluated by reversed phase- and size-exclusion-HPLC. The analysis of microsphere content after processing and 6 months of storage showed that insulin did not undergo any chemical modification within microspheres. On the contrary, during the period of sustained release insulin was transformed in a high-molecular weight product, the amount of which was related to the surfactant used. In conclusion, polysorbate 20 at 3% w/v concentration was the most effective in giving regular shaped particles with both good insulin loading and slow release, and limiting insulin modification within microspheres.
这项工作的目的是制备负载胰岛素的微球，以便在颗粒加工和胰岛素释放过程中保持肽的稳定性。我们的策略是将使用表面活性剂提高胰岛素稳定性的概念与优化微球的整体特性（如尺寸、形态、肽负载量和释放）相结合。通过复乳溶剂蒸发技术将牛胰岛素包封在聚（丙交酯-共-乙交酯）（PLGA 50:50，Resomer RG504H）微球中。通过向初级乳液中添加三种不同浓度（1.5%和3.0% w/v）的非离子表面活性剂泊洛沙姆188、聚山梨酯20和脱水山梨醇单油酸酯80来制备微球。发现表面活性剂的存在会降低平均直径并影响微球的形态。在表面活性剂存在下，尤其是脱水山梨醇单油酸酯80，胰岛素包封效率以浓度依赖模式降低。发现表面活性剂对胰岛素与PLGA之间相互作用以及初级乳液稳定性的影响是胰岛素包封的主要决定因素。微球中胰岛素的释放是双相的，所有制备批次均显示出初始突释效应，随后是接近零级的释放。初始突释与位于微球表面或其附近的胰岛素分子的存在有关。在表面活性剂存在下，观察到与单独包封胰岛素的微球相比，胰岛素释放更快。通过反相和尺寸排阻高效液相色谱法评估加工、储存和释放后微球内胰岛素的稳定性。加工后和储存6个月后对微球内容物的分析表明，微球内胰岛素未发生任何化学修饰。相反，在持续释放期间，胰岛素转化为高分子量产物，其含量与所用表面活性剂有关。总之，浓度为3% w/v的聚山梨酯20在提供形状规则、胰岛素负载良好且释放缓慢以及限制微球内胰岛素修饰方面最为有效。
