Inclusion complexation of amide-typed local anaesthetics with beta-cyclodextrin and its derivatives .1. Physicochemical characterization

Qualitative aspects of the inclusion complexation of two local anaesthetics of the amide-type (LAs), bupivacaine (BVC) and lidocaine (LDC) with three cyclodextrins (CDs), beta-cyclodextrin (beta CD) and its alkylated derivatives 2-hydroxypropyl-beta-cyclodextrin (HP beta CD) and heptakis (2,6-di-o-methyl)-beta-cyclodextrin (DM beta CD), were studied in the solid state by infrared spectroscopy (IR) and differential scanning calorimetry (DSC). The LDC-beta CD couple was also investigated in aqueous solution by nuclear magnetic resonance (H-1-NMR and C-13-NMR). This first part of a study dealing with improvement in LA administration provided clear indications about LA-CD complexation. Qualitative modifications in a number of peaks or bands obtained from spectral methods as well as thermal analysis signed the inclusion, showing that the freeze-drying method was suitable for obtaining inclusion complexes of LAs with CDs.