Abstract: AIM: To develop an LC-MS method to determin the concentration of terazosin in human plasma and its application. METHODS: Shimadzu 2010 LC-MS and Thermo Hypersil-Hypurity C₁₈(150 mm×2.1 mm, 5 μm) were used in the experiment. The column temperature was set at 40 ℃. 20 mmol/L ammonium acetate-methanol-acetonitrile(65∶20∶15, V/V/V) was used as mobile phase and the flow rate was 0.25 mL/min. Ion mass spectral(m/z) of 388, 384 were selected to quantify terazosin, prazosin (internal standard), respectively. The plasma sample were alkalinizedwith 3 mol/L sodium hydroxide buffer and extracted with dichloromethane. The sample room temperature was set at 5 ℃ and the injection volume was 5 μL. RESULTS: Terazosin was linear range from 0.25-50 ng/mL respectively, the limitation of terazosin was about 0.25 ng/mL. The extraction recoveries from plasma was more than 70%, method recovery was 96.0%-97.6%, the intraday and interday precisions were less than 15%. The method was high sensitivity, stability and specificity and has already been used for pharmacokinetics study of terazosin in human successfully. CONCLUSION: The method is simple, accurate, repetitive for the determination of terazosin in human plasma and suitable for bioavailability and bioequivalence study of terazosin.

Key words: Terazosin, LC-MS, Bioavailability, Bioequivalence