Biocolloid and Fluid Physics Group, Department of Applied Physics, Faculty of Sciences, University of Granada, 18071 Granada, Spain.
Int J Pharm. 2012 Feb 28;423(2):161-6. doi: 10.1016/j.ijpharm.2011.12.025. Epub 2011 Dec 23.
In this work we have investigated how steric surfactants influence the metabolic degradation of emulsions (lipolysis). To do so, we have prepared submicron emulsions stabilized with Pluronic F68, Pluronic F127, Myrj 52 or Myrj 59, four non-ionic surfactants with key differences on their structure. Submicron emulsions have been prepared also with mixtures of these surfactants with different proportions between them. Then, in vitro methods have been applied to analyze the lipolysis of these emulsions, both under duodenal and intravenous conditions, to simulate lipolysis after oral and intravenous administration. Our results show that the properties of the surfactant influence dramatically the lipolysis rates observed both under duodenal and intravenous conditions, e.g., intravenous lipolysis was completely blocked when Pluronic F127 was used, while it was almost complete within 6h when using Myrj 52. The reason for this seems to be the steric hindrance that the surfactant produces around the droplet and at the interface. As a result, we can modify the lipolysis patterns by changing some characteristics of the surfactant, or by varying the proportion between two surfactants in a mixture. These findings may be applied in the development of novel strategies to rationally design submicron emulsions as lipophilic drug carriers.
在这项工作中，我们研究了空间位阻表面活性剂如何影响乳液（脂解）的代谢降解。为此，我们制备了用 Pluronic F68、Pluronic F127、Myrj 52 或 Myrj 59 稳定的亚微米乳液，这四种非离子表面活性剂在结构上有很大的差异。我们还制备了这些表面活性剂与不同比例混合物的亚微米乳液。然后，应用体外方法分析这些乳液的脂解，包括在十二指肠和静脉条件下，模拟口服和静脉给药后的脂解。我们的结果表明，表面活性剂的性质极大地影响了在十二指肠和静脉条件下观察到的脂解速率，例如，当使用 Pluronic F127 时，静脉内脂解完全被阻断，而当使用 Myrj 52 时，几乎在 6 小时内完全脂解。原因似乎是表面活性剂在液滴周围和界面处产生的空间位阻。因此，我们可以通过改变表面活性剂的某些特性，或通过改变混合物中两种表面活性剂的比例来改变脂解模式。这些发现可应用于开发新型策略，以合理设计作为亲脂性药物载体的亚微米乳液。
