Solid lipid nanoparticles (SLNs) are in submicron size range nanoparticles and are made of biocompatible and biodegradable materials (mainly composed of lipids and surfactants) capable of incorporating both lipophilic and hydrophilic drugs. SLNs are also considered as substitute to other colloidal drug systems, also used as controlled systems and targeted delivery. SLNs can be considered as an alternative for oral drug delivery vehicle to improve the oral bioavailability of drugs, associated reduction of drug toxicity and stability of drug in both GIT and plasma. There are different techniques used for the preparation of SLNs. Generally, the preparation of SLNs and any other nanoparticle system necessitates a dispersed system as precursor; otherwise particles are produced through the use of a particular instrumentation. This review provides the summary on the techniques or methods used for the development of SLNs of poorly water soluble drugs for improved drug delivery. Keywords: Solid lipid nanoparticles, controlled delivery, precursor, techniques.

From last thirty years, solid lipid nanoparticles (SLNs) gain much importance as drug delivery vehicle for enhanced delivery of the drugs, proteins, nutraceuticals and cosmetics. SLNs defined as a submicron size range nanoparticle with below 1000 nm and are mainly composed of lipids and surfactants, capable of incorporating both lipophilic and hydrophilic drugs. SLNs also used as controlled systems, targeted delivery and altered therapeutic efficacy purpose. A wide variety of methods such as double emulsion, solvent evaporation, ultra sonication, high-pressure homogenization and microemulsion used for SLNs production. This review provides the significance of SLNs in drug delivery with highlighting on selection of excipients, drug release mechanism, principles and limitations associated with their physicochemical and surface morphological characterization. Keywords: Solid lipid nanoparticles, enhanced delivery, preparation, characterization, application.