Advantages of solid lipid nanoparticles for wound healing
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During the recent years, more attentions have been focused on lipid base drug delivery system to overcome some limitations of conventional formulations. Among these delivery systems solid lipid nanoparticles (SLNs) and nanostructured lipid carriers (NLCs) are promising delivery systems due to the ease of manufacturing processes, scale up capability, biocompatibility, and also biodegradability of formulation constituents and many other advantages which could be related to specific route of administration or nature of the materials are to be loaded to these delivery systems. The aim of this article is to review the advantages and limitations of these delivery systems based on the route of administration and to emphasis the effectiveness of such formulations.
Keywords: Drug delivery systems, Nanoparticles, Nanostructured lipid carriers (NLCs), Routes of administration, Solid lipid nanoparticles (SLNs)
1. INTRODUCTION
Lipid nanoparticles as drug delivery systems were considered from the beginning of the 19th century by professor R. H. Müller from Germany and Professor M. Gascon from Italy(1,2). These nanoparticles are manufactured from solid or mixture of solid and liquid lipids and stabilized by emulsifiers.
Lipids used in these nanoparticles are biocompatible and completely tolerated by the body like triglycerides, fatty acids, steroids, and waxes. In addition, using combination of emulsifiers could stabilize the formulations more efficiently. Lipid nanoparticles have many advantages in comparison to other particulate systems such as the ease of large-scale production(3), biocompatible and biodegradable nature of the materials(4), low toxicity potential(5), possibility of controlled and modified drug release(6), drug solubility enhancement and the possibility of both hydrophilic and lipophilic drug incorporation. Lipid nanoparticles are different from micro-emulsions, which are clear thermodynamically stable dispersion of oil and water that are stabilized by surfactants and cosurfactants(7,8). The most important parameters in lipid nanoparticles characterization are particle size and size distribution, zeta potential, polymorphism, degree of crystallinity, drug loading, entrapment efficiency, and drug release. There are three different types of lipid nanoparticles: homogenous drug-lipid matrix, drug enriched core and drug enriched shell. Drug release from lipid nanoparticles is mostly dependent on the matrix type and location of drug in matrix formulation; for example in the third type, drug release from the nanocarriers shows more sustained release profile. The composition of lipid matrix, surfactant concentration and manufacturing parameters, such as temperature and stirring rate, can also affect drug release profiles. Probably the most important reasons of using lipid nanoparticles, as a suitable alternative of previous polymeric nanoparticles, are the ease of large-scale production and their low toxicity potential(1).