Design of Experiments (DoE) Driven Fabrication of Surface Modified Liposomes of Olmesartan Medoxomil for Improved Oral Bioavailability
摘要
Olmesartan Medoxomil (OLM) is a prodrug of an angiotensin II receptor antagonist and a P-glycoprotein (P-gp) substrate that is converted into Olmesartan by esterases, resulting in low oral bioavailability (26%). The aim of the present study was to formulate Olmesartan Medoxomil liposomes by thin film hydration method using Vitamin E TPGS (P gp inhibitor). Initial screening of excipients was conducted using the One Factor At A Time (OFAT) approach, while optimization was performed using Box-Behnken Design (BBD). The drug-to-lipid ratio, the amount of cholesterol, and the surfactant were identified as independent variables, with vesicle size (nm) and entrapment efficiency (%) as dependent variables. Key process parameters were evaluated through OFAT analysis, and the formulation was optimized using BBD. The prepared liposomes were characterized through vesicle size (nm), zeta potential (mV), drug loading (%), Transmission Electron Microscopy (TEM), Differential Scanning Calorimetry (DSC), Fourier Transform Infrared Spectroscopy (FTIR), and Gas Chromatography (GC), followed by in vitro dissolution and in vivo pharmacokinetic study in 12 wistar rats. The vesicle size and entrapment efficiency of the optimized formulation were found to be 112.1 nm and 98.88% respectively. In vitro drug release studies were conducted in the USP-II apparatus exhibited a biphasic release pattern compared to the marketed formulation Olmezest®10. In vivo pharmacokinetic studies in wistar rats showed a significant increase in oral bioavailability (3.23 times) of the liposomal formulation of Olmesartan Medoxomil (OLM-LIPO) in comparison to the marketed formulation Olmezest®10.