Development and evaluation of sulfobutylether-β-cyclodextrin inclusion complexes of etoricoxib for enhancing dissolution

Etoricoxib is a BCS class II drug with poor aqueous solubility and analgesic and anti-inflammatory properties. Complexation with cyclodextrins is one of the widely used methods, amongst others, for enhancing the solubility and bioavailability of drugs. In current research work, inclusion complexes of etoricoxib using modified forms of cyclodextrin, i.e., captisol were prepared using kneading, evaporation, and freeze-drying methods to improve the solubility and dissolution characteristics. Etoricoxib inclusion complexes (ratio 1:1) were formulated using kneading, evaporation, and freeze-drying methods. The formulated inclusion complexes were evaluated for phase solubility, equilibrium solubility studies, Fourier transform infrared spectroscopy, powder X-ray diffraction, scanning electron microscopy, differential scanning calorimetry studies, in vitro drug release, similarity factor and in vivo studies. The freeze-drying method produced inclusion complexes with the highest equilibrium solubility (ten times that of the pure drug). Fourier transform infrared spectroscopy studies showed no drug-polymer interaction. Differential scanning calorimetry and scanning electron microscopy studies suggested the incorporation of the drug into inclusion complexes of cyclodextrin. In vitro dissolution studies of kneading, evaporation and freeze-drying method inclusion complexes showed 66.53%, 79.13% and 88% drug release, respectively, in 3h, whereas pure drug exhibited 61.77% drug release in 3 h. The f1 value obtained was less than 50, which is indicative of a significant difference in release characteristics of kneading, evaporation and freeze-drying methods with that of the marketed formulation. In vivo studies indicated that inclusion complexes formulated by the freeze-drying method showed better analgesic and anti-inflammatory effects in comparison to formulations prepared by kneading and evaporation methods. It is concluded that the formulation prepared by the freeze-drying method led to a significant enhancement of dissolution and solubility rate of etoricoxib in comparison to the formulation prepared by the kneading method and evaporation method.