Validated Stability-Indicating Spectrophotometric Techniques for the Determination of Quetiapine in the Presence of its Oxidation-Induced Degradation Products

The International Conference on Harmonization (ICH) guideline entitled “Stability Testing of New Drug Substances and Products” requires that stress testing be carried out to elucidate the inherent stability characteristics of the active substance. Susceptibility to oxidation is one of the required tests. Also, evaluation of the hydrolytic and the photolytic stability is required. Four new selective, precise, and accurate methods are described for the determination of Quetiapine (QTI) in the presence of its oxidation-induced degradation products in both the raw material and pharmaceutical preparations. Method A and B is based on third-derivative (3D), and fourth-derivative (4D) spectrophotometric measurement of QTI in methanolic solution at the zerocrossing point of its oxidation-induced degradation products (at 272–290, and 260–281 nm, respectively). Method C is a 1DD spectrophotometric method based on the simultaneous use of the first derivative of the ratio spectra and the measurement of peak amplitude at 250- 277 nm. Method D uses a pH-induced absorbance-difference spectrophotometry with (ΔA) measurement at 217 nm. These methods are suitable as stability-indicating for the determination of QTI in the presence of its oxidation-induced degradation products either in the bulk powder or in pharmaceutical preparations.