Preparations of Ethosome-like Catanionic Vesicles from Ion-Pair Amphiphiles( IPAs ) for Dermal Drug Delivery

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Preparations of Ethosome-like Catanionic Vesicles from Ion-Pair Amphiphiles( IPAs ) for Dermal Drug Delivery Yu-Min Yang Department of Chemical Engineering, National Cheng Kung University, Tainan 70101, Taiwan ABSTRACT Ethosomes which are phospholipid vesicular systems embodying ethanol in relatively high concentrations have ever been discovered for enhanced skin delivery of drugs. The development of competent ethosome-like catanionic vesicles for dermal drug delivery is demonstrated in this work. Double-chained ion-pair-amphiphiles (IPAs or catanionic surfactants) were prepared from single-chained cationic and anionic surfactants by the precipitation method. These lipid-like surfactants were thereafter used as the material to prepare the catanionic vesicles with the aid of ethanol as the cosolvent in aqueous buffer solution by a simple semispontaneous process. Formability and physical stability of the as-prepared ethosome-like catanionic vesicles were discussed based on the viewpoint of mixed solvent dielectric constant. The potential application of the ethosome-like catanionic vesicles as nano-carriers in dermal drug delivery was illustrated by the encapsulation of hydrophobic and hydrophilic drugs. Furthermore, effects of ethanol and cholesterol addition on physical stability, bilayer membrane rigidity, encapsulation efficiency, and release rate of the ethosome-like catanionic vesicles were systematically studied. The performance of ethosome-like catanionic vesicles as drug delivery nano-carriers, eventually, can be tailored by the concentrations of ethanol and. cholesterol. The results of gelation of drugs loaded ethosome-like catanionic vesicles by water soluble polymers with and without hydrophobical modifications, as revealed by the phase maps and the rheological properties, then provide useful information for practical use of the ethosome-like catanionic vesicles in dermal delivery of drugs. INTRODUCTION Liposome and catanionic vesicle While liposomes are usually constituted by double-chained amphiphiles, such as phospholipids, a great deal of work has been done to demonstrate the possibility of forming vesicles from single-chained surfactants under specific conditions [1,2]. This is the case for mixtures of cationic and anionic surfactants, whose association through the interactions of their polar headgroups can mimic the double-chained structures of phospholipids. Since Kaler et al. [3] gave the example of spontaneous vesicle formation from mixed cationic and anionic singlechained surfactants using cetyltrimethylammoniumtosylate (CTAT) and sodium dodecylbenzenesulfonate (SDBS) in water, the term “catanionic vesicle” is now commonly accepted to describe the vesicular system formed from mixed cationic-anionic surfactants. With the potential applications in drug delivery, catanionic vesicles were also studied among others for their hemolytic toxicity and suggested that drug-participating catanionic vesicle can be used as a safe and an efficient vehicle for sustained drug release [4,5].

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