ABSTRACT
Valsartan (VST) is a poorly soluble antihypertensive drug characterized by its limited dissolution rate and low bioavailability. This study aims to improve VST solubility and dissolution rate via developing liquisolid tablets (LSTs) containing a self-nanoemulsifying drug delivery system (SNEDDS), which is expected to enhance VST bioavailability. This aim was achieved via two designs of experiment. The first was the simplex-lattice design to optimize VST-loaded-SNEDDS using sesame oil, Tween 80, and polyethylene glycol 400. The second was the 32-3-level factorial design to optimize the liquisolid system using the SNEDDS-loaded VST and Neusilin®US2 as a carrier and fumed silica as a coating material. Different excipient ratios (X1) and varioussuper-disintegrants (X2) were also used in developing the optimized VST-LSTs. Thein vitrodissolution of VST from LSTs was compared with the marketed product (Diovan®). Non-compartmental analysis of plasma data after extravascular input with the linear trapezoidal method was used to calculate thepharmacokinetic parameters of the optimized VST-LSTs compared with the marketed tablet in male Wistar rats. The optimized SNEDDS compromised 24.9% sesame oil, 33.3% surfactant, and 41.8% cosurfactant, giving 173.9 nm size and 63.9 mg/ml loading capacity. Also, the SNEDDS-loaded VST tablet revealed good quality attributes with the release of 75% of its content in 5 min and 100% within 15 min. On the other hand, the marketed product took 1 h for the entire drug to be released.Moreover, the maximum plasma concentration (Cmax) of the optimizedVST-LSTwas6585.33 ng/ml within 1 h (Tmax), compared to 2884.67 ng/ml within 2 h of the marketed tablet.The relative bioavailability of the SNEDDS-loaded VST tablet was 213.7% compared to that of the marketed tablet, indicating that this formulation approach could be applied for increasing solubility, dissolution behavior in GIT, and bioavailability of poorly water-soluble drugs.
