Buspirone Hydrochloride Loaded In Situ Nanovesicular Gel as an Anxiolytic Nasal Drug Delivery System: In Vitro and Animal Studies

Nasal nanovesicular gels of buspirone hydrochloride (BH) were prepared and characterized aiming for sustained delivery and enhancing bioavailability. Buspirone hydrochloride has low bioavailability of about 4% after oral administration due to first pass metabolism. Buspirone hydrochloride nanovesicles were formulated by thin film hydration method (TFH). The selected nanovesicular formulation was incorporated into two types of in situ gels (pH-induced and thermoreversible) using carbopol 974P and poloxamer 407 (P407), respectively, together with different mucoadhesive polymers. The in situ gels were examined for pH, gelling capability, viscosity, content uniformity, mucoadhesiveness, and in vitro drug release. The ex vivo permeation performance of the in situ gel formulations that showed the most sustained release was also assessed. The in vivo study was done by the determination of BH blood level in albino rabbits after nasal administration. Results revealed that nanovesicles prepared using Span 60 and cholesterol in a ratio of 80:20 showed the highest EE% (70.57 ± 1.00%). The ex vivo permeation data confirmed higher permeability figures for carbopol formulation in comparison to poloxamer formulations. The in vivo study data showed an increase of 3.26 times in BH bioavailability when formulated into the carbopol nanovesicular in situ gel relative to control (nasal drug solution).