ABSTRACT
Self-micro emulsifying drug delivery systems (SMEDDS) indicate the formulations forming transparent micro emulsions with oil droplets ranging between 100 nm and 250 nm. The Lipid Formulation Classification System was introduced as a working model in 2000, and an extra ‘type’ of formulation was added in 2006. Self-emulsification takes place when the entropy change favouring dispersion is greater than the energy required to increase the surface area of the dispersion. For highly lipophilic drugs, lipids may enhance the extent of lymphatic transport and increase bioavailability directly or indirectly via reduction in first pass metabolism. The polarity of the lipid phase is one of the main factors that govern the drug release from the micro-emulsions. If surfactant or co-surfactant is contributing to the greater extent in drug solubilization then there could be a risk of precipitation, as dilution of SMEDDS will lead to lowering or solvent capacity of the surfactant or co-surfactant.
