Formulation and Evaluation of Danazol Tablets Using Cyclodextrin Complexation for Improved Oral Bioavailability

Danazol, a BCS Class II synthetic isoxazole derivative of 17α-ethinyl testosterone, exhibits extremely poor aqueous solubility (< 1 μg/mL) and characteristically low, highly variable oral bioavailability (2–6%) from conventional formulations, necessitating high daily doses of 200–800 mg and predisposing patients to dose-dependent androgenic adverse effects. This study investigated cyclodextrin inclusion complexation as a solubility and dissolution enhancement strategy for danazol tablet development. Danazol–cyclodextrin inclusion complexes were prepared using β-cyclodextrin (β-CD) and hydroxypropyl-β-cyclodextrin (HP-β-CD) at drug-to-cyclodextrin molar ratios of 1:1 and 1:2 by three methods: physical mixing, kneading, and solvent evaporation, yielding eight formulations (F1–F8). Complexes were characterized by Fourier Transform Infrared spectroscopy (FT-IR), Differential Scanning Calorimetry (DSC), and Powder X-Ray Diffraction (PXRD). Phase solubility studies were conducted following the Higuchi–Connors method. Tablet formulations (T1–T6) were prepared by direct compression and evaluated for pharmacopoeial quality attributes and in-vitro dissolution performance. Phase solubility studies confirmed AL-type profiles for both cyclodextrins, with HP-β-CD demonstrating superior stability constants (Ks = 2847.3 M⁻¹ vs 685.4 M⁻¹ for β-CD) and 22.3-fold solubility enhancement at 10 mM. FT-IR, DSC, and PXRD analyses converged in identifying F8 (danazol:HP-β-CD, 1:2, solvent evaporation) as the optimally amorphized complex, exhibiting complete loss of danazol crystallinity. The optimized tablet T6 achieved 93.8% drug dissolution within 90 minutes — a 5.9-fold improvement over pure danazol control (16.8%) — with T50% reduced from >90 to 10.4 minutes (87% reduction). All tablet formulations met pharmacopoeial quality specifications. Drug release followed Fickian diffusion (Korsmeyer–Peppas R² = 0.9882, n = 0.428). Cyclodextrin inclusion complexation, particularly with HP-β-CD via solvent evaporation, represents a scientifically validated, pharmaceutically viable, and industrially scalable strategy for dramatically improving danazol oral bioavailability. The direct compression tablet manufacturing approach further enhances commercial feasibility.