Formulation and In Vitro Evaluation of Self Microemulsifying Drug Delivery System Containing Atorvastatin Calcium

Objective: The aim of this study was to develop a new dosage form as an alternative to the classical tablet forms of atorvastatin calcium (AtrCa). The formulation strategy was to prepare an optimum self micro emulsifying drug delivery system (SMEDDS) to overcome the problem of low solubility of the active substance. Methods: In this study, pseudo ternary phase diagrams were plotted determined by the solubility studies. According to the solubility studies; oleic acid was used as the oil phase, Tween 20 and Span 80 were used as the surfactants and ethanol was used as the co-surfactant. SMEDDS formulations were characterized according to pH, electrical conductivity, density, refractive index, viscosity, emulsification time, dispersibility, robustness of dilution stability, droplet size, polidispersity index, zeta potential, transmittance %, cloud point, content quantification %, chemical and physical stability. The lipolysis study was conducted under fed and fasted conditions. In vitro release studies and kinetic evaluation were carried out. Permeability studies were also examined with Caco-2 cell culture. Results: The droplet size of the optimized formulation did not change significantly in different medias over the test time period. Improved SMEDDS formulation will progress steadily without precipitating along the gastrointestinal tract. Lipolysis studies showed that the oil solution had been exposed to high amount of lipolysis compared to the SMEDDS formulation. The release rate of AtrCa from AtrCa- SMEDDS formulation (93.8%, at 15 minutes) was found as increased when the results were compared with commercial tablet formulation and pure drug. The permeability value of AtrCa from AtrCa- SMEDDS formulation was found higher than pure AtrCa and commercial tablet formulation, approximately 9.94 and 1.64 times, respectively. Conclusion: Thus, lipid-based SMEDDS formulation is a potential formulation candidate for lymphatic route in terms of the increased solubility of AtrCa.