Quantitative analysis of trazodone in human plasma by using HPLC-fluorescence detector coupled with strong cation exchange chromatographic column: Application to a pharmacokinetic study in Chinese healthy volunteers

A simple, selective, and sensitive high performance liquid chromatography (HPLC) procedure has been developed for determination of trazodone in human plasma. Prazosin was employed as the internal standard (IS). Sample preparation involved liquid–liquid extraction by methyl tert-butyl ether after alkalinization with ammonia. The HPLC separation was performed on a CAPCELL PAK SCX column (250 mm × 4.6 mm, 5.0 μm, Shiseido, Japan) with a mobile phase of acetonitrile/80 mmol/L ammonium phosphate (pH adjusted to 6.0) (60:40, v/v) at a flow rate of 1.2 mL/min. The peaks were detected by using fluorescence detector (excitation wavelength 320 nm and emission wavelength 440 nm). The extraction recovery was 72.6–88.3% and the method was over the concentration range of 5.0–2486 ng/mL with a lower limit of quantitation (LLOQ) of 5.0 ng/mL using 300 μL of plasma. The intra- and inter-day accuracy of the method at three concentrations ranged from 96.7% to 104.2% for trazodone with precision of 2.9–3.7%. This validated method was successfully applied to a pharmacokinetic study enrolling 12 Chinese volunteers administered a single oral trazodone hydrochloride extended-release tablet of 75 mg.