More than 60 percentage of new drugs synthesized suffered from poor water solubility limitation. Water poor solubility consequently leads poor oral bioavailability in many new molecules. Selection of appropriate formulation for such drugs is creating a lot many challenges to the formulation experts. Lipid based drug delivery is once of conceptual approaches to improve oral bioavailability of such drugs. One of such formulation is solid lipid nanoparticles, which can further improve the bioavailability, therapeutic efficacy and can reduce overall dose to be delivered. Solid lipid nanoparticles (SLNs) are the effective lipid based colloidal carriers which were introduced as an alternative to the conventional carriers. Typically they enhance the oral bioavailability of the low aqueous soluble drugs due to their potential to enhance gastrointestinal solubilization and absorption via selective lymphatic uptake. SLNs can be prepared by High shear homogenization, Hot homogenization, Cold homogenization, Ultra sonication or high speed homogenization, Solvent emulsification/evaporation, Supercritical fluid techniques, Spray drying method or Double emulsion method. There are basically three different models for the incorporation of active ingredients into SLN that are Homogeneous matrix model, Drug-enriched shell model and Drug-enriched core model. Characterization of SLN is a serious challenge due to the colloidal size of the particles and the complexity and dynamic nature of the delivery system. The important parameters which need to be evaluated for the SLNs are, particle size, size distribution kinetics (zeta potential), degree of crystallinity and lipid modification (polymorphism), coexistence of additional colloidal structures (micelles, liposome, super cooled, melts, drug nanoparticles), time scale of distribution processes, drug content, in vitro drug release and surface morphology.
In current research SLNs of Exemestane is prepared by homogenization technique. Preliminary process optimization and screening is performed for drug to lipid ratio, amount of organic and aqueous phase, amount of surfactant, homogenization speed, homogenization time and sonication time. Prepared SLNs evaluated for particle size, percentage entrapment efficiency, percentage drug loading, zeta potential analysis, in-vitro dissolution study, scanning electron microscopy, stability studies, in vitro cytotoxicity screening and in vivo bioavailability studies.