Design and Development of Solid Dispersion of Valsartan by a Lyophilization Technique: A 3² Factorial Design Approach

Background: Valsartan is a poorly water-soluble drug having limited oral bioavailability. Its absorption and onset of action mostly depend on its solubility. Therefore, its solubility needs to be enhanced for maximum therapeutic action. Objective: The aim of this work is to formulate valsartan-mannitol Solid Dispersions (SDs) by bottom- up process based-freeze drying (lyophilization) techniques for solubility enhancement of valsartan. Methods: Valsartan is BCS class II drug having low aqueous solubility and low oral bioavailability. It needs to improve its solubility for the fastest onset of action. SDs were prepared using water as a solvent and tertiary butyl alcohol (TBA) as anti-solvent. A 3² (three level-two factors) response surface methodology was used to detect the effect of independent variables such as the amount of valsartan (X1) and the amount of mannitol (X2) on dependent variables such as solubility (Y1) and particle size (Y2). Results: Prepared SDs were characterized by employing solubility, particle size determination, Differential Scanning Calorimetry (DSC), X-Ray Diffraction (XRD), zeta potential, Fourier Transform Infrared Spectroscopy (FTIR) and field emission scanning electron microscopy (FESEM). The optimum values of solubility and particle size were 115.14μg/L and 242.5 nm, respectively. Conclusion: Solid dispersions of valsartan-mannitol were successfully prepared by simple lyophilization techniques and seem to be promising for enhancing dissolution rate (solubility) and oral bioavailability of valsartan.