Inclusion Complex between Local Anesthetic/2-hydroxypropyl-beta-cyclodextrin in Stealth Liposome

The drugs delivery system in the treatment of diseases has advantages such as reduced toxicity, increased availability of the drug, etc. Therefore, studies of the supramolecular interactions between local anesthetics (LAs) butamben (BTB) or ropivacaine (RVC) complexed with 2-hydroxypropyl-beta-cyclodextrin (HP-beta CD) and carried in Stealth liposomal (SL) are performed. H-1-NMR nuclear magnetic resonance (DOSY and STD) were used as the main tools. The displacements observed in the H-1-NMR presented the complexion between LAs and HP-beta CD. The diffusion coefficients of free BTB and RVC were 7.70 x 10(-10) m(2) s(-1) and 4.07 x 10(-10) m(2) s(-1), and in the complex with HP-beta CD were 1.90 x 10(-10) m(2) s(-1) and 3.64 x 10(-10) m(2) s(-1), respectively, which indicate a strong interaction between the BTB molecule and HP-beta CD (98.3% molar fraction and Ka = 72.279 L/mol). With STD-NMR, the encapsulation of the BTB/HP-beta CD and RVC/HP-beta CD in SL vesicles was proven. Beyond the saturation transfer to the LAs, there is the magnetization transfer to the hydrogens of HP-beta CD. BTB and RVC have already been studied in normal liposome systems; however, little is known of their behavior in SL.