Optimizing Intranasal Amisulpride Loaded Nanostructured Lipid Carriers: Formulation, Development, and Characterization Parameters

Background: Nanostructured lipid carriers (NLCs) are lipid-based nanoparticles composed of a mixture of solid and liquid lipids, which are stabilized by the outer surface of a surfactant. Objective: This research aimed to prepare intranasal nanostructured lipid carriers loaded with amisulpride to enhance its dissolution and bioavailability using different formulation compositions. Methods: Amisulpride nanostructured lipid carriers were formulated using ultra-sonication methods. Solid lipids like stearic acid, palmitic acid, and glyceryl monostearate were used, while liquid lipids like oleic acid, Imwitor 988, and isopropyl myristate were employed. Surfactants used were cremophor®EL, tween 80, and span 20 with different co-surfactants: Transcutol HP, triacetin, and propylene glycol in different ratios. The key metrics used in this study's evaluation were particle size, polydispersity index, zeta potential, entrapment efficiency, and loading efficiency. The formulations with the best characteristics were also subjected to an in-vitro release test. Results: The results showed a significant shift in some evaluation criteria with a non-significant change in other characterizations upon switching between different types and ratios of compositions. A biphasic release pattern was also observed. The optimum formula F19 was found to have 68.309±0.38 nm, 0.2408±0.004, -20.64±0.11 mV, 95.75±0.26 and 18.07±0.36, respectively. It was safe on the sheep nasal membrane. Conclusion: The right combination of the formulation compositions based on studying the effect of each factor on the main formulation characteristics can serve as the basis for a successful intranasal amisulpride-loaded nanostructured lipid carrier.