Formulation Development and Evaluation of Lipid Based Nanoparticles of Valsartan by Microemulsification

Valsartan is an antihypertensive drug with poor oral bioavailability ranging from 10-35% because of poor solubility, dissolution and most importantly, extensive first pass hepatic metabolism. For improving solubility and oral bioavailability of Valsartan, Valsartan loaded solid lipid nanoparticles (VSLNs) have been developed using stearic acid as lipid, Tween 80 as surfactant and PEG 400 as cosurfactant by the microemulsion method. Optimized VSLNs were having particle size of 403±0.71 nm (PDI= 0.685±0.005), 96.50±0.05% drug entrapment efficiency and zeta potential of -10.44±0.01 mV. Valsartan nanodispersion was evaluated by Transmission Electron Microscopy (TEM) for morphological study. Optimized Valsartan nanodispersion was lyophilized and further Differential Scanning Calorimetry (DSC) of lyophilized VSLNs was performed for checking solid state characterization. In vitro drug release study of Valsartan nanodispersion as well as lyophilized VSLNs was performed in phosphate buffer solution pH 6.8 using dialysis diffusion bag and drug release from lyophilized VSLNs (98.71±0.001% within 8 hours) was found to be faster as compared to Valsartan nanodispersion (98.97±0.001% within 12 hours). Ex-vivo drug release study was also performed for Valsartan nanodispersion and plain drug and drug release was found to be 98.75±3.18% and 38.3±1.16% within 12 hrs, respectively. Stability study was conducted for six months. Based on all the results, it is concluded that SLNs prepared by microemulsification show promise for improving the oral bioavailability of Valsartan.