Analysis of intermolecular interaction of dimethyl sulphoxide and dimethyl formamide solvates of febuxostat by thermal and spectral methods

Pseudopolymorphism is the phenomenon wherein a compound is obtained in crystalline forms that differ in the nature or stoichiometry of included solvent molecules. If solvent molecules are included in a crystal there are special reasons for such an occurrence. The chief amongst them are the intermolecular interactions between solute and solvent.;In this study the drug used is Febuxostat, a xanthine oxidase inhibitor used in the treatment of hyperuricemia and chronic gout. A polymorphic form III of Febuxostat was generated by an antisolvent crystallization method, (acetone as solvent and n-hexane as antisolvent). FebuxostatForm III was used as a starting material for further studies. Febuxostat-Form III was mixed with different solvents like dimethyl sulphoxide, dimethyl formamide, acetone, acetonitrile, ethyl acetate, methanol and tert butyl methyl ether individually to form a mixture(solvent assisted grinding), which was further dried and analyzed by DSC, TGA and PXRD techniques. Febuxostat-Form III was found to form solvates with DMSO and DMF. Solubility studies were carried out to determine the solubility of Febuxostat in different solvents. FTIR studies of the solvates described the intermolecular interactions between the drug and the solvent. The FTIR results determined the tendency of DMSO and DMF to self- associate and to form weak and strong hydrogen bonds (Interactions) with the solute molecule.