Khan Azhar Yaqoob, Talegaonkar Sushama, Iqbal Zeenat, Ahmed Farhan Jalees, Khar Roop Krishan
Department of Pharmaceutical Medicine, Faculty of Pharmacy, Jamia Hamdard, New Delhi 110062, India.
Curr Drug Deliv. 2006 Oct;3(4):429-43. doi: 10.2174/156720106778559056.
Multiple emulsions are complex polydispersed systems where both oil in water and water in oil emulsion exists simultaneously which are stabilized by lipophillic and hydrophilic surfactants respectively. The ratio of these surfactants is important in achieving stable multiple emulsions. Among water-in-oil-in-water (w/o/w) and oil-in-water-in-oil (o/w/o) type multiple emulsions, the former has wider areas of application and hence are studied in great detail. Formulation, preparation techniques and in vitro characterization methods for multiple emulsions are reviewed. Various factors affecting the stability of multiple emulsions and the stabilization approaches with specific reference to w/o/w type multiple emulsions are discussed in detail. Favorable drug release mechanisms and/or rate along with in vivo fate of multiple emulsions make them a versatile carrier. It finds wide range of applications in controlled or sustained drug delivery, targeted delivery, taste masking, bioavailability enhancement, enzyme immobilization, etc. Multiple emulsions have also been employed as intermediate step in the microencapsulation process and are the systems of increasing interest for the oral delivery of hydrophilic drugs, which are unstable in gastrointestinal tract like proteins and peptides. With the advancement in techniques for preparation, stabilization and rheological characterization of multiple emulsions, it will be able to provide a novel carrier system for drugs, cosmetics and pharmaceutical agents. In this review, emphasis is laid down on formulation, stabilization techniques and potential applications of multiple emulsion system.
多重乳液是复杂的多分散体系，其中水包油乳液和油包水乳液同时存在，分别由亲脂性和亲水性表面活性剂稳定。这些表面活性剂的比例对于获得稳定的多重乳液很重要。在水包油包水（w/o/w）型和油包水包油（o/w/o）型多重乳液中，前者具有更广泛的应用领域，因此得到了详细研究。本文综述了多重乳液的配方、制备技术和体外表征方法。详细讨论了影响多重乳液稳定性的各种因素以及针对w/o/w型多重乳液的稳定化方法。多重乳液有利的药物释放机制和/或速率以及体内命运使其成为一种通用的载体。它在控释或缓释药物递送、靶向递送、掩味、提高生物利用度、酶固定化等方面有广泛的应用。多重乳液也被用作微囊化过程中的中间步骤，并且是用于口服递送在胃肠道中不稳定的亲水性药物（如蛋白质和肽）的越来越受关注的体系。随着多重乳液制备、稳定化和流变学表征技术的进步，它将能够为药物、化妆品和药剂提供一种新型载体系统。在这篇综述中，重点阐述了多重乳液体系的配方、稳定化技术和潜在应用。
