Enhanced Oral Absorption of Amisulpride Via a Nanostructured Lipid Carrier-Based Capsules: Development, Optimization Applying the Desirability Function Approach and In Vivo Pharmacokinetic Study

Amisulpride (AMS), a second generation antipsychotic, suffers from low oral bioavailability (48%). This might be due to its pH-dependent solubility or being a substrate of P-glycoprotein efflux pump. Nanostructured lipid carriers (NLCs) were proposed in this study to enhance the oral absorption of AMS. AMS-NLCs were prepared by solvent evaporation technique according to (2¹.4¹.3¹) factorial design, whereas the type of solid lipid (tripalmitin or Gelucire® 43/1), lipid to drug ratio (7:1, 10:1, or 13:1) and type of external suspending medium (double distilled water, 0.5% TSP pH 12, 1% HPMC or 2.5% glycerin) were the independent variables. The average entrapment efficiency, particle size, polydispersity index, and zeta potential of the prepared formulations ranged from 29.01 to 69.06%, 184.9 to 708.75 nm, 0.21 to 0.59, and - 21 to - 33.55 mV, respectively. AMS-NLCs were optimized according to the desirability function to maximize the entrapment efficiency and minimize the particle size. Formulae G12, G10, and G7 with the highest desirability values of 0.915, 0.84, and 0.768, respectively, were chosen for further investigations. Novel AMS-NLCs capsules were prepared from the lyophilized formulations (TG7 and MG10) to enhance stability and increase patient compliance. The capsules were evaluated in terms of weight variation, content uniformity, and in vitro release pattern. The pharmacokinetics of AMS-NLCs capsules (formula TG7) were tested in rabbits compared to the commercial Amipride® tablets. The relative bioavailability of AMS-NLCs capsules was found to be 252.78%. In conclusion, the NLC-based capsules show potential to improve the oral bioavailability of AMS.