Drug delivery systems multiple emulsions

Other drug-delivery systems may include double emulsions, usually W/O/W, for transporting hydrophilic dmgs such as vaccines, vitamins, enzymes, hormones [441], The multiple emulsion also allows for slow release of the delivered drug and the time-release mechanism can be varied by adjusting the emulsion stability. Conversely, in detoxification (overdose) treatments, the active substance migrates from the outside to the inner phase. 

Vladisavljevic et al. reported on the production of multiple w/o/w emulsions for drug-delivery systems by extruding a coarse w/o/w emulsion five times through a SPG membrane [68]. 

Multiple emulsions usually refer to series of complex two-phase systems that result from dispersing an emul sion into its dispersed phase. Such systems are often referred to as water-in-oil-in-water (W/OAV) or oil-in-water-in-oil (O/W/0) emulsions, depending on the type of internal, intermediate, and continuous phase. Multiple emulsions were early recognized as promising systems for many industrial applications, such as in the process of immobilization of proteins in the inner aqu eous phase (37) and as liquid membrane systems in extraction processes (38). W/O/W emulsions have been discussed in a number of technical applications, e.g., as prolonged drug-delivery systems (39-44), in the context of controlled-release formulations (45), and in pharmaceutical, cosmetic, and food (46) applications. 

G. T. Vladisavljevic, M. Shimizu, T. Nakashima, Production of multiple emulsions for drug delivery systems by repeated SPG membrane homogenization Influence of mean pore size, interfacial tension and continuous phase viscosity, J. Membr. Sci. 2006, 284, 373. 

The examples given here involve lung surfactant replacement compositions and surfactant systems used for 2D protein crystallization. Other potential systems include direct, reverse and multiple emulsions for drug and gene delivery, as well as micro- and nano-sized gas bubbles for O2 delivery and diagnosis [3, 4]... 

In addition to traditional dermal and transdermal delivery formulations, such as creams, ointments, gels, and patches, several other systems have been evaluated. In the pharmaceutical semisolid and liquid formulation area,these include sprays, foams, multiple emulsions, microemulsions, liposomal formulations, transfersomes, niosomes, ethosomes, cyclodextrins, glycospheres, dermal membrane structures, and microsponges. Many of these novel systems use vesicles to modulate drug delivery. Novel transdermal... 

Ghosh LK, Ghosh NC, Thakur RS, Pal M, Gupta BK. 1997. Design and evaluation of controlled-release W/O/W multiple-emulsion oral liquid delivery system of chlorpheniramine maleate. Drug Dev Ind Pharm 23 1131-1134. 

Multiple emulsions have been widely studied as means of delivering drugs via oral, topical, and parenteral routes. The applications include protein delivery (Cournarie et al., 2004), delivery of antibiotics to the vagina (Tedajo et al., 2005), sustained delivery (Vaziri and Warburton, 1994), and vaccine delivery (Bozkir and Hayta, 2004). The immunological response to a vaccine also depends on the route of administration. Most current vaccines are administered intramuscularly, which induces immunization as a systemic immunity. However, the live polio vaccine and the live typhoid vaccine are administered orally. Local immunization (oral, intranasal, or intravagina) may be preferred, since mucosal surfaces are the common entrance to many pathogens. Moreover local immunization induces both mucosal and systemic immunity. Ease of administration and avoidance of systemic side effects are additional advantages of local immunization (Walker, 1994 Shalaby, 1995). Nevertheless, successful local immunization has only been achieved with a limited number of oral vaccines. Also there are very few studies on multiple emulsions used in the immunization process, especially on parenteral and oral administration. 

Bozkir A, Hayta G. 2004. Preparation and evaluation of multiple emulsions water-in-oil-in-water (W/O/W) as delivery system for influenza virus antigens. J Drug Target 12(3) 157-164. 

A. J. Khopade and N. K. Jain review the anticancer activity of surface-modified fine multiple emulsions. These systems are characterized by nano-sized/miceUar internal aqueous phase and highly viscous or solidified oil phase dispersed in an aqueous phase. Surface modification permits new applications in anticancer drug delivery and drug targeting. 

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