Studies On The Polymorphism Of Agomelatine And The Cocrystals Of Tranilast

The pharmaceutical solid forms include polymorphism, solvates, amorphous,salts and cocrystals. Different solid forms may have different interactions betweenmolecules, which strongly influences physicochemical properties, such as meltingpoint, solubility, dissolution rate, stability and bioavailability. Therefore, it isimportant to investigate that the polymorphism of the pharmaceutical solid forms.In this work, the complexes of tranilast and the pharmaceutical polymorphs ofagomelatine were studied. Four fields are primarily studied in this paper as below:1. The significances and the current research status of the pharmaceuticalpolymorphism researches were introduced in chapter1.2. Tranilast is an anti-allergic drug which is widely used. However, an inherentdrawback of tranilast is its low aqueous solubility. Besides, tranilast has aphotochemically unstable cinnamoyl group that undergoes two degradation pathwayincluding isomerization and dimerization under photo-irradiation. Two cocrystals ofTL with urea and nicotinamide, as well as one salt of tranilast with cytosine, wereobtained and characterized by infrared spectra, thermogravimetric analyses, powderand single crystal X-ray diffractions. The maxmum solubility and the photo-stabilityof tranilast can also be improved after the formation of cocrystals and salt.3. In chapter3, the1:1salt of tranilast with2,6-diaminopyridine which exists in two polymorphic forms. Both of the forms were characterized by various analyticaltechniques. Factors affecting the formation of salt polymorphs, such as heat and forcewere investigated.4. The polymorphism of agomelatine was investigated in chapter4. The singlecrystal of agomelatine form IV was prepared by evaporation. What’s more, the simple,convenient and environmental preparation method of agomelatine form I was studied.