Effect of mechanochemical inclusion of triamterene into sulfobutylether-β-cyclodextrin and its improved dissolution...

The formation of inclusion complexes between triamterene (TT) and cyclodextrins (CDs) to increase the water apparent solubility of TT was investigated. UV data showed that the binding constant of the TT/sulfobutylether-β-cyclodextrin (SBE-β-CD) inclusion complex was 510 L/mol. The phenyl ring of TT was inserted into the secondary hydroxy face of SBE-β-CD, as demonstrated by ¹H-¹H rotating frame nuclear Overhauser effect spectroscopy NMR. Physicochemical properties of solid TT/SBE-β-CD complexes prepared by physical mixing, kneading, freeze-drying, and mechanochemical methods were studied by X-ray diffraction and ¹³C cross-polarization and magic angle spinning NMR. With the mechanochemical method, the diffraction peak corresponding to TT disappeared, indicating the formation of an inclusion complex. The results of the dissolution test revealed that the solid complex obtained by the mechanochemical method improved the dissolution of TT. The water apparent solubility of TT can be improved by simple mechanical mixing without organic solvents, and improved bioavailability after oral administration is expected.