Interaction of Lornoxicam with Natural Cyclodextrin in Solid and Solution State

The solid state properties and dissolution behaviour of Lornoxicam (LX) with β-cyclodextrin (βCD) were investigated. The binary system of LX with βCD was prepared by the kneading method. Drug-cyclodextrin interactions in solution state were investigated by the phase solubility analysis and saturation solubility study as per Higuchi and Connors. Phase solubility diagram allowed the determination of association constant between LX and βCD and showed stability constant value 401 M⁻¹ suggesting drug is having sufficient affinity towards βCD cavity and formation of stable inclusion complex. As the concentration of βCD increases, solubility of pure drug increases showing AL type of phase solubility curve. Differential scanning calorimetry, Fourier transformation infrared spectroscopy and powder X-ray diffractometry study were used to study the solid state properties of all binary systems. The results indicate partial interaction of the drug with βCD in the physical mixture and complete interaction in the kneaded complex. Saturation solubility study revealed that solubility of the inclusion complex were enhanced to several extent compared to pure drug whereas dissolution properties of inclusion complex were evaluated according to the USP type II paddle apparatus. The dissolution rate of LX-βCD inclusion complex was notably increased as compared to pure drug as well as its physical mixture. The inclusion complex showed 90% drug released in less than 10 min.