Inclusion complexes of fluconazole with β-cyclodextrin: physicochemical characterization and in vitro evaluation of its formulation

Fluconazole (FZ) is a triazole antifungal drug administered orally or intravenously. It is employed for the treatment of mycotic infections. However, the efficacy of FZ is limited with its poor aqueous solubility and low dissolution rate. One of the important pharmaceutical advantages of cyclodextrins is to improve pharmacological efficacy of drugs due to increasing their aqueous solubility. The aim of present study was to prepare an inclusion complex of FZ and beta-cyclodextrin (beta-CD) to improve the physicochemical and biopharmaceutical properties of FZ. The effects of beta-CD on the solubility of FZ were investigated according to the phase solubility technique. Complexes were prepared with 1: 1 M ratio by different methods namely, freeze-drying, spray-drying, co-evaporation and kneading. For the characterization of FZ/beta-CD complex, FZ amount, practical yield %, thermal, aqueous solubility, XRD, FT-IR and NMR (H-1 and C-13) analysis were performed. In vitro dissolution from hard cellulose capsules containing FZ/beta-CD complexes was compared to pure FZ and its commercial capsules and evaluated by f(1) (difference) and f(2) (similarity) factors. Paddle method defined in USP 31 together with high pressure liquid chromatographic method were used in in vitro dissolution experiments. It was found that solubility enhancement by FZ/beta-CD complexes depends on the type of the preparation method. High release of active agent from hard cellulose capsules prepared with beta-CD complexes compared to commercial capsules was attributed to the interactions between beta-CD and active agent, high energetic amorphous state and inclusion complex formation.