Comprehensive characterisation of the flurbiprofen/β-cyclodextrin inclusion complex using X-ray techniques and NMR spectroscopy

Abstract

A new pharmaceutical form of a nonsteroidal anti-inflammatory drug complex composed of racemic flurbiprofen (FP) with a macrocyclic compound, forming a guest-host complex, was investigated. As with the other propionic acid compound, ketoprofen, three methods (co-precipitation, evaporation and heating-under-reflux) were used to prepare the β-cyclodextrin (β-CD) complex with FP. 1HNMR and X-ray powder diffraction (XRPD) in solution and solid state, respectively, were used to monitor the guest-host interactions. Only the heating-under-reflux method turned out to be suitable for host-guest complex formation. For the prospective method, a complex was prepared in the form of a crystalline powder, which was used as a starting material for the preparation of monocrystals suitable for X-ray crystallographic studies. The selected crystal was used to collect the diffraction data, which enabled the crystal and the molecular structure of the complex to be solved. This work is a connecting element in understanding the complete view of the interaction of FP with β-CD, mainly due to the results obtained with the X-ray single-crystal diffraction technique.