Stability-indicating HPLC method for the determination of quetiapine: Application to tablets and human plasma

A stability-indicating reversed-phase high performance liquid chromatographic method was developed for the analysis of the antipsychotic drug quetiapine. Quetiapine was determined in presence of two of its degradation products; quetiapine N-oxide and quetiapine lactam. The analysis was carried out using a 250 mm x 4.6 mm i.d., 5 mu m particle size Zorbax SB-Phenyl column. Mobile phase containing a mixture of acetonitrile and 0.02M phosphate buffer (50:50) at pH=5.5 was pumped at a flow rate of 1 mL/min with UV detection at 254nm. The method showed good linearity in the range of 0.08-20 mu g/mL with limit of detection (S/N=3) 0.03 mu g/mL (3.3 x 10(-8) M). The suggested method was successfully applied for the analysis of quetiapine in bulk, tablets, and human plasma with average recoveries of 99.96 +/- 1.25%, 101.37 +/- 0.481%, and 100.82 +/- 1.53%, respectively. The proposed method was also applied for the determination of quetiapine in the presence of some co-administered drugs as clomipramine, carbamazepine, and fluconazole.