Abstract
An advanced mode of drug delivery system has been developed to overcome the major drawbacks associated with conventional drug delivery systems. This review gives a detailed idea about a nanoemulsion system. Nanoemulsions are nano-sized emulsions, which are manufactured for improving the delivery of active pharmaceutical ingredients. These are the thermodynamically stable isotropic system in which two immiscible liquids are mixed to form a single phase by means of an emulsifying agent, i.e., surfactant and co-surfactant. The droplet size of nanoemulsion falls typically in the range 20–200 nm. The main difference between emulsion and nanoemulsion lies in the size and shape of particles dispersed in the continuous phase. In this review, the attention is focused to give a basic idea about its formulation, method of preparation, characterization techniques, evaluation parameters, and various applications of nanoemulsion.
Highlights
Introduction enhance the therapeutic efficacy of the drug and minimize adverse effect and toxic reactions
Droplet size analysis of nanoemulsion is measured by a diffusion method using a light-scattering, particle sizeanalyzer counter, LS 230
Droplet size analysis of nanoemulsion can be performed by transmission electron microscopy (TEM) (Bouchemal et al 2004a, b; Alka et al 2007; Farhan et al 2008)
Summary
The main components of nanoemulsion are oil, emulsifying agents, and aqueous phases (Gasco et al 1991; Kriwet and Muller-Goymann 1995; Trotta 1999). A mixture of oil and water may yield a crude temporary emulsion, which upon standing, will separate in two distinct phases due to the coalescence of the dispersed globules. Emulgents or emulsifying agents can impart stability to such systems. In addition to its emulsifying properties, should be nontoxic and its taste, odour and chemical stability should be compatible with the product. Some of the desirable properties of an emulgent are: (1) it should be able to reduce the surface tension to below 10 dynes/cm, (2) it should be adsorbed rapidly around dispersed phase globule to form a complete and coherent film to prevent coalescence, (3) it should help in building up an adequate zeta potential and viscosity in the system so as to impart optimum stability, and (4) it should be effective in a fairly low concentration. Emulgents form monomolecular, multimolecular or particulate films around the dispersed globules (Sharma and Jain 1985)
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