Three new polymorphs (forms I, II, and III) of natural cholinesterase inhibitor Huperzine A were discovered through a comprehensive polymorph screening experiment. Their structures were elucidated by single-crystal structure analysis and characterized by powder X-ray diffraction, Fourier transform-infrared spectroscopy, and DXR Raman microscope. The physicochemical properties of these new forms were investigated by thermal analysis (TGA and DSC) and dynamic vapor sorption (DVS) isotherms. The powder dissolution rates were compared with the marketed monohydrate form. Thermodynamic stability, phase transformation, E–T diagram, and drugability properties are also discussed in detail.

Single crystal structures of blockbuster antihypertensive drug Valsartan are revealed the first time in this report. Two new highly crystalline forms, named form E and an ethanol solvate form F, were discovered and fully characterized by PXRD, Raman, IR, TG, DSC, and DVS. Conformational flexibility and single crystal structures are discussed in detail. Physicochemical properties, such as hygroscopicity, chemical stability, crystallinity, and dissolution behaviors, are compared with the marketed solid-state form (amorphous state). The results show that the newly discovered highly crystalline form E presents a remarkably different dissolution behavior and superior chemical stability.