Lipid core nanocapsules-loaded tacrolimus: Development and evaluation of quality parameters

This study aimed to revalidate an HPLC-based analytical methodology to determine  tacrolimus within lipid-core nanocapsules and to evaluate the quality of such nanosystems. Chromatographic separation was achieved by employing a C18 column as a stationary phase and a ternary mixture of acetonitrile: water: phosphoric acid (700:299:1 v/v) as the mobile phase. The revalidated method proved to be linear in the range of 1-60 µg.mL−1 for tacrolimus (r2 >0.999). Detection and quantification limits were 45.38 ng.mL-1 and 137.51 ng.mL-1, respectively, which assures the methodology sensitivity. The method was also precise (RSD = 1.78% between samples). Besides, the methodology demonstrated accuracy and robustness. The lipid-core nanocapsules-loaded tacrolimus showed exclusively nanosized particles (±190 nm and polydispersity index of ≤v0.2), negative zeta potential (-13.67±1.16), and slightly acidic pH (5.58 ± 0.06), with a content of 98.90±2.32%  and encapsulation rate of 99.23±0.32%.  Tacrolimus-loaded in lipid-core nanocapsules-loaded tacrolimus showed stability for at least 30 days at room temperature and a sustained release profile compared to the drug in solution.