Abstract: Objective A RP-HPLC method with fluorescence detector was established to determine telmisartan in human plasma.Methods Internal standard method quantifying telmisartan concentration in plasma was performed and valsartan was used as the internal standard. Plasma samples containing drug were extracted with benzene under acidic condition, followed by drying with nitrogen. The residual products were redissolved with mobile phase prior to analysis. Separation was performed on a reverse phase ZORBAX Eclipse XDB-C18 column(4.6×150 mm,5 μm), equipped with a pre-column of the same material(4.6×12.5 mm, 5 μm). The mobile phase contained methanol-acetonitrile-10 mmol/L potassium dihydrogen phosphate buffer, pH 3.2(5∶40∶55, v/v/v). The flow rate was set at 1.0 mL/min and the injection volume was 20 μL. The excitation and emission wavelengths were 250 nm and 375 nm, respectively. The column temperature was 25 ℃.Results No intrinsic substances interfered with analysis of telmisartan. The retention times were 8.8 min for telmisartan and 10.7 min for valsartan. The good linear relationship was obtained over the range(1～180)μg/L and the equations were determined by least squares linear regression analysis. The linear equation was A=0.2769R+0.03788. The linearity of the relationship between peak area ratio and amount ratio was demonstrated that the correlation coefficient was 0.9995. The limit quantification(LOQ) was set at 1 μg/L of telmisartan in human plasma. The average recovery rates were 97.53%, 104.6% and 105.1 % for plasma quality control(QC) samples at 2.0, 30, 70 μg/L, respectively. The RSDs of inter-and intra-day were all less than 7% for low, medium, high plasma QC samples. The intra and inter-assay precision and accuracy of the quality control and limit of quantification were satisfactory in all cases. Plasma samples were stable in the chromatographic rack for 24 h at room temperature, but we recommended storing processed plasma samples at 4 ℃ until the analysis.Conclusion The developed method was validated with respect to selectivity, linearity, accuracy, LOQ and stability. The experimental datum has proved that the above described method would provide accurate, rapid, simple and sensitive measurements of telmisartan in plasma. It is more suitable to determine telmisartan concentration in plasma and study the pharmacokinetics of telmisartan.

Key words: telmisartan, RP-HPLC, FLD