Nano-emulsions pharmaceutical

Sadurm, N., Solans, C., Azemar, N. and Garci a-Celma, M.J. (2005) Studies on the formation of O/W nano-emulsions, by low-energy emulsification methods, suitable for pharmaceutical aplications. Emulsion polymerization initiation of polymerization in monomer droplets., 26, 438-445. 

Bouchemal, K., Briangon, S., Perrier, E. and Fessi, H. (2004) Nano-emulsion formulation using spontaneous emulsification solvent, oil and surfactant optimisation. International Journal of Pharmaceutics, 280, 241-251. 

However, despite these difficulties, several companies have introduced nanoemulsions in the market and, within the next few years, the benefits will be evaluated. Nano-emulsions have been used in the pharmaceutical field as drug delivery systems [5]. 

The capacity of solubilizing compounds in the droplets of a nano-emulsion gives the possibility of developing applications, implying the transport of these compounds through a continuous phase in which they are insoluble. Pharmaceutical and cosmetic applications for which nonpolar compounds are solubilized in oil droplets dispersed in aqueous media would be typical, and other possible applications in food or agrochemical fields have also been described [1,2],... 

Although nano-emulsions are thermodynamically imstable systems, they may possess high kinetic stability. This property together with their transparent or translucent visual aspect and a viscosity similar to that of water makes them of special interest for practical applications. Nano-emulsions are used in the pharmaceutical field as drug delivery systems [8,17, 18,25,28-33], in cosmetics as personal-care formulations [2,4,6,7,10,19-21,23,24,27], in agrochemical applications for pesticide delivery [3,34,35], in the chemical industry for the preparation of latex particles [9,22,26,36-38], etc. In addition, the formation of kinetically stable liquid/liquid dispersions of such small sizes is of great interest from a fimdamental viewpoint. 

Nano-emulsions have found increasing use in many different applications. The advantages of nano-emulsions over conventional emulsions (or macroemulsions) are a consequence of their characteristic properties, namely small droplet size, high kinetic stability, and optical transparency. In addition, nano-emulsions offer the possibility of using microemulsion-like dispersions without the need for high surfactant concentrations. In the following, the most relevant applications of nano-emulsions in the chemical, pharmaceutical, and cosmetic fields are summarized. 

The use of ttaditional disperse systems, e.g., macroemulsions, in the pharmaceutical industry has been limited due to manufacturing complexity and stability problems [117]. The characteristic properties of nano-emulsions (kinetic stability, small and controlled droplet size, etc.) make them interesting systems for pharmaceutical applications. Indeed, nano-emulsions are used as drug delivery systems for administration through various systemic routes. There are numerous publications on nano-emulsions as drug delivery systems for parenteral [17,18,28,29,118-124], oral [25,125-129], and topical administration, which includes the administration of formulations to the external surfaces of the body skin [32,130,131] and to the body cavities nasal [30,132] as weU as ocular administration [31,133-136]. Moreover, many patents concerning pharmaceutical applications of nano-emulsions have been registered [17,18,25,137-145]. An application of nano-emulsions in this field has been in the development of vaccines [33,146-147]. 

Another application of nano-emulsions in the pharmaceutical field is in ocular administration (a topical administration). Nano-emulsions are used as ocular delivery systems to sustain the pharmacological effect of drugs in comparison with their respective aqueous solutions [133]. 

Within the last 30 years, micro emulsions have also become increasingly significant in industry. Besides their application in the enhanced oil recovery (see Section 10.2 in Chapter 10), they are used in cosmetics and pharmaceuticals (see Chapter 8), washing processes (see Section 10.3 in Chapter 10), chemical reactions (nano-particle synthesis (see Chapter 6)), polymerisations (see Chapter 7) and catalytic reactions (see Chapter 5). In practical applications, micro emulsions are usually multicomponent mixtures for which formulation rules had to be found (see Chapter 3). Salt solutions and other polar solvents or monomers can be used as hydrophilic component. The hydrophobic component, usually referred to as oil, may be an alkane, a triglyceride, a supercritical fluid, a monomer or a mixture thereof. Industrially used amphiphiles include soaps as well as medium-chained alcohols and amphiphilic polymers, respectively, which serve as co-surfactant. 

Lin W, Yang XL, Winston Ho W. Fheparation of nniform-sized multiple emulsions and micro/nano particulates for drug delivery by membrane emulsification. Journal of Pharmaceutical Sciences. 20H 100(l) 75-93. 

Micelles are nano or micro structures with a hydrophobic core and a hydrophilic shell. They form above a eritieal eoneentration called the eritical micellar concentration (CMC) as a result of the self-association of amphiphilic molecules to minimize hydrophobic interactions. Micellar surfactants and polymers are widely used in the pharmaceutical industry as formulation aids in solids, semi-solids, suspensions, emulsions, and solutions. One of the... 

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