Nanoemulsified System of a Poorly Water Soluble Drug

Atorvastatin calcium is a selective, competitive inhibitor of HMG-CoA reductase. The oral bioavailability of atorvastatin (parent drug) is approximately 14% and the systemic availability of HMG-CoA reductase inhibitory activity is approximately 30%. It is mainly due to its poor aqueous solubility and pre systemic metabolism. In this study we aimed to prepare and evaluate the atorvastatin loaded nanoemulsion. The term nanoemulsion refers to a thermodynamically stable isotropically clear dispersion of two immiscible liquids made stable by an interfacial film of surfactant molecules. Various oils were screened for solubilising atorvastatin calcium and sunflower oil, which shows greatest solubility, was selected as oily phase. Phase diagrams were constructed using sunflower oil, Tween 80 (surfactant) and Capmul MCM (co-surfactant) to study the relationship between the components of the nanoemulsion and their phase behaviour. Two formulations were selected from the o/w nanoemulsion region and subjected to thermodynamic stability studies. The Globule size, viscosity, zeta potential and refractive index of the formulated nanoemulsions were determined. Transmission electron microscopy studies were also carried out in the selected nanoemulsion.