ABSTRACT
Objective To evaluate the polymorphism of levonorgestrel by kinds of analysis technologies, and get the preponderant pharmaceutical polymorph by in vitro assessment including the stability and solubility. Methods Three polymorphs were obtained by quick solvent removal and precipitation methods. These polymorphs were characterized by X-ray powder diffraction (PXRD), differential scanning calorimetry (DSC), infrared absorption spectroscopy (IR), Raman spectroscopy and microscope. Furthermore,the stability was studied by X-ray powder diffraction analysis technology and using the curve of solubility to evaluate the dissolution rate of the three crystal forms. Results The levonorgestrel polymorphs α,β and γ were identified. The results of stability indicated that the levonorgestrel polymorphs α and β were metastable while the levonorgestrel polymorph γ was stable,and the dissolution rate of α, β, γ decrease in turn. Conclusion The levonorgestrel polymorph α is preponderant pharmaceutical polymorph. And the research on preponderant pharmaceutical polymorph of levonorgestrel provides scientific basic data for its clinical drug evaluation and establishing the quality standards.