Investigation of inclusion complex of trazodone hydrochloride with hydroxypropyl-β-cyclodextrin

Inclusion complex of trazodone hydrochloride (TRD) with hydroxypropyl-β-cyclodextrin (HP-βCD) has been investigated by 1H NMR, 13CNMR, 2D NMR, FTIR and UV/visible spectroscopy. It was testified that the inclusion complex was formed between HP-βCD and trazodone. The stability constant K1:1 and the 1:1 stoichiometry of complexation was determined. NMR analysis confirmed the inclusion and to provide information on the behaviour of TRD inside the cavity of HP-βCD. It was found that the fragment of TRD molecule, the benzene ring entered into the cavity of HP-βCD. Concerning the structure of the inclusion complex, a Cl− in orientation of trazodone in hydroxypropyl-β-cyclodextrin cavity has been confirmed by 2D NMR spectroscopy. Based on the enhancement of the absorbance of trazodone produced throught complex formation, a spectrophotometric method for the determination of trazodone in bulk aqueous solution in presence of HP-βCD was developed, which overcome the effect of condition change on the determination of trazodone. The linear relationship between the absorbance and trazodone concentration was obtained in the range of 5–30 μg ml−1 with a correlation coefficient of 0.9998. The detection limit was 0.27 μg ml−1.