Preparation and in-vitro evaluation of self emulsifying drug delivery system of antihypertensive drug valsartan

Abstract

The present study deals with formulation of a valsartan based Self emulsifying drug delivery system of a poorly water soluble drug. SEDDS are the isotropic mixtures of oil, surfactant, co surfactant and drug that form oil in water microemulsion when introduced into aqueous phase under gentle agitation. The present research work describes a Self Emulsifying Drug Delivery System (SEDDS)   of valsartan using Castor oil, Tween-80, PEG-600. Valsartan is an angiotensin converting enzyme (ACE) inhibitor with limited water solubility, which accounts for a low and variable oral bioavailability (19-25%). Hence, the main objective of study was to formulate SEDDS of valsartan in order to achieve a better dissolution rate which would further help in enhancing oral bioavailability. Pseudo-ternary phase diagrams were plotted to check for the micro-emulsification range and also to evaluate the effect of valsartan on the emulsification behavior of the phases. The mixtures consisting of oil (castor oil) with surfactant (tween 80), co-surfactant (PEG 600) were found to be optimum formulations. Prepared SEDDS formulations were tested for microemulsifying properties and the resultant microemulsions were evaluated for robustness to dilution, assessment of efficiency of self emulsication, emulsification time, turbidity measurment, viscosity, drug content and in-vitro dissolution. The optimized SEDDS formulation further evaluated for heating cooling cycle, centrifugation studies and freeze thaw cycling, particle size distribution, zeta potential were carried out to confirm the stability of the formed SEDDS. The formulation was found to show a significant improvement in terms of the drug release with complete release of drug within 60 minutes. Thus, Self microemulsifying formulation of valsartan was successfully developed.