Improved solubility and stability of rifampicin as an inclusion complex of acyclic cucurbit[n]uril

The poor solubility and low stability of rifampicin limited its therapeutic efficacy. One of the common strategies is to form an inclusion complex to address the problems. In this study, acyclic cucurbit[n]uril was used for encapsulation of rifampicin to form an inclusion complex. The inclusion complex was prepared by the kneading method and characterized by DSC, SEM, FT-IR, NMR, PXRD, and UV-Vis spectroscopy. The results confirmed the formation of 1:1 inclusion complex. The drug content was calculated to be 27.35 +/- 0.54%. The aqueous solubility of rifampicin was increased 20-fold by complexation with acyclic cucurbit[n]uril. Moreover, the thermo-stability and photo-stability of free rifampicin and inclusion complex were investigated by HPLC. Rifampicin was stabilized by encapsulating the piperazine ring in the cavity of acyclic cucurbit[n]uril. In addition, the MIC of free RIF and RIF.ACB were determined by using in vitro experiments. It was found that rifampicin complexed by acyclic cucurbit[n] uril exhibited similar antibacterial activities against strain H37Rv to rifampicin alone. [GRAPHICS] .