Determination And Pharmacokinetic Studies Of Two Statins In Human Plasma By Ultra Performance Liquid Chromatography-tandem Mass Spectrometry

Objective:To develop and validate specific,sensitive and rapid methods for the determination and pharmacokinetic studies of simvastatin and lovastatin in human plasma by ultra performance liquid chromatography-tandem mass spectrometry.Method:After a liquid-liquid extraction process with diethyl ether - n-hexane -isopropanol (80:20:3,v/v/v)of 500μL plasma,simvastatin and lovastatin(internal standard)were separated on an ACQUITY UPLC^TMBEH C₁₈column with isocratic elution at a flow-rate of 0.25 mL/min. The mobile phase was a mixture of acetonitrile and water(containing 10 mmol/L ammonium acetate,pH4.5)(85:15,v/v).The detection was performed on a triple-quadrupole tandem mass spectrometer by multiple reaction monitoring(MRM)mode via electrospray ionization(ESI). The quantification was performed using the transitions of m/z 419â†'m/z 199 for simvastatin and m/z 405â†'m/z 199 for lovastatin(internal standard),respectively.Lovastatin plasma samples were prepared by liquid-liquid extraction with n-hexane-methylene dichloride-isopropanol(20:10:1,v/v/v)of 500μL plasma,separated on ACQUITY UPLC^TMBEH C₁₈column with isocratic elution.The mobile phase was acetonitrile and water(containing 5 mmol/L ammonium acetate)(85:15,v/v)at a flow-rate of 0.35 mL/min. Multiple reaction monitoring(MRM)using the precursorâ†'product ion combination of m/z 427â†'m/z 325,and m/z 441â†'m/z 325 was employed to quantify lovastatin and simvastatin (internal standard),respectively.Result:The linear calibration curves were obtained over the concentration range 0.0510～20.4 ng/mL for simvastastin in human plasma.The intra- and inter-day precision values(RSD)were less than 10%and the accuracy(RE)was -2.7%～1.2%at all three QC levels.The main parameters obtained after an oral dose of 40 mg simvastatin in capsules to 20 healthy volunteers were as follows:C_maxwas found to be 12.2±4.61 ng/mL,T_maxobserved was 1.7±0.6 h,the value t_1/2was 4.2±1.6 h,AUC_0-tand AUC_0-∞obtained were 42.27±27.61 ng·h/mL and 43.99±28.60 ng·h/mL,respectively.The standard calibration curves for lovastatin were linear in the concentration range of 0.0250～50.0 ng/mL in human plasma.The intra- and inter-day precision values(RSD)were not above 14%and the accuracy(RE)was -4.9%～6.0%at all three QC levels.The main pharmacokinetics parameters obtained after an oral dose of 40 mg lovastatin in capsules to 18 healthy volunteers were 8.90₊1.93ng/mL for C_max,2.3±0.5 h for T_max,3.4±1.6 h for t_1/2,31.30±14.94 ng·h/mL for A UC_0-tand 32.19±15.29 ng·h/mL for A UC_0-∞,respectively.Conclusion:The methods are proved to be of high specificity,sensitivity,speed and have been successfully utilized for the evaluation of the pharmacokinetics of simvastatin capsules and lovastatin capsules.