Physicochemical, in silico and in vivo evaluation of a danazol–β-cyclodextrin complex

Inclusion complexation of danazol with β-cyclodextrin (BCD) in aqueous solution, in solid state and in silico state was investigated to examine the interactions of danazol with BCD. The study also explored the potential application of danazol–β-cyclodextrin complex as an oral antiovulatory agent. Phase solubility analysis suggested formation of first-order soluble complex with stability constant 972.03 M−1 while Job's plot affirmed 1:1 stoichiometry. Solution state complexation in water was studied by ultra violet absorption, circular dichroism and nuclear magnetic resonance (1H NMR) spectroscopy. The solid state complexes were evaluated by differential scanning calorimetry, powder X-ray diffractometry, fourier transform infrared spectroscopy and scanning electron microscopy. Thermodynamic studies in water indicated exothermic nature of inclusion complexation. Molecular modeling was used to help establish the mode of interaction of BCD with danazol. 1H NMR analysis suggested that the protons of steroidal skeleton of danazol are preferably involved in the complexation with BCD, which was confirmed by molecular dynamic simulations. An inclusion complex model has been established for explaining the observed enhancement of solubility of danazol in water by BCD. Moreover, in mouse model, danazol–β-cyclodextrin complex at 51.2 mg/kg (equivalent to 400 mg human dose) showed 100% anovulation when given orally.