LAUSR

Abstract Newly established green TLC-densitometric and RP-HPLC methods were developed and validated for simultaneous determination of quetiapine (QUT) (an antipsychotic drug) and the co-administrated drug, paroxetine (PAR) (an antidepressant drug). Both drugs are widely prescribed for treatment of bipolar depression. The proposed TLC-densitometric method was based on separation of the studied components and the internal standard (vincamine (VINC)) using a developed system of ethyl acetate: ethanol: ammonia solution 33% (8: 2:0.05, by volume) on TLC silica gel 60 F254 plates and scanning at 240 nm. Linear relationships were obtained over a concentration range of 150–3000 ng/band for both using 1000 ng/mL of vincamine (VINC) as an internal standard. On the other hand, the proposed RP-HPLC method depended on separation of the studied components and the internal standard (vincamine) using a mixture of methanol: 0.05 M KH2PO4 (pH 4.3) (70:30, v/v) on XTerra® HPLC RP C18 column (4.6 mm × 250 mm, 5 µm) at a flow rate of 1 mL/min, and UV detection at 240 nm. Linearity was achieved on the concentration range of 150–5000 ng/mL for both using 1000 ng/mL of VINC as an internal standard. The greenness profile of the developed methods was assessed and compared with reported HPLC method using the analytical Eco-Scale as an assessment tool. The proposed methods were found to be greener than the reported method. Furthermore, the developed methods were validated following FDA guidelines and all parameters met the acceptance criteria. In addition, they were successfully used to study the pharmacokinetic parameters of both QUT and PAR after their co-administration in rats and results showed that both drugs affected the pharmacokinetic parameters of each other when administrated together. The developed methods can be used for further monitoring of the studied drugs in patients.