Determination Of Venlafaxine In Human Plasma By High Performance Chromatography-mass Spectrometry And Study On Bioequivalence

ObjectivesA highly sensitive, specificitive, and simplely operative performance liquid chromatography-mass spectrometry method was developed and used for the determination of concentration of venlafaxine in human plasma. To study pharmacokinetic characteristics of venlafaxine in healthy volunteers by the main pharmacokinetic parameters to evaluate the bioequivalence and to ensure the safety and efficacy of clinical medicine.Methods20 voluneers were given a single dose and multi-dose and double-cross oral soft capsule of venlafaxine tested and reference prepared venlafaxine dose of 75mg,and taken forearm vein blood at different time by randomized double cycle and preparations and cross-cycle test.Performance liquid chromatography-mass spectrometry method was used to determine the different moments in the venlafaxine plasma concentration. Inertsil(?) ODS-3 column (2.1×50mm I.D, particle size 3μm), mobile phase was methanol-10mmol/L ammonium acetate(85:15,v/v), Waters Quattro micro API triple quadrupole tandem mass spectrometer.The Lamivudine was taken as the internal standard.To calculate the subjects and the reference preparation using major pharmacokinetic parameters, Cmax, Tmax, AUC0-t, AUC0-∞analysis of variance and 90% confidence interval method to determine bioequivalence.ResultsThe linear range of venlafaxine 2.00～200ng·ml-1. The lowest limit of quantification (LLOQ) was 2.0 ng·ml-1. Recovery rate of more than 85%, days and day RSD less than 15%.Test preparation and the reference preparation pharmacokinetic parameters of single dose Tmax were 6.10±0.97 and 5.80±1.01 h; Cmax were 60.99±35.81 and 63.88±38.19 ng·ml-1, t1/2 were 11.69±3.48 and 11.90±4.42 h; AUC0-t were 1292.31±1317.63 and1251.13±1227.50 ng·h·ml-1, AUC0-∞were 1386.08±1429.44 and 1351.47±1354.36 ng·h·ml-1. AUC0-t in terms of soft gelatin capsules venlafaxine relative bioavailability of an average of 102.1±9.5%.Evaluation of bioequivalence was made by analysis of variance and confidence interval method. The results show that the tested agents, the AUC0-t venlafaxine 90% confidence interval for the reference preparation of the corresponding parameters of 98.0%～105.4%, the AUC0-∞venlafaxine 90% confidence interval for the reference preparation of the corresponding parameters of 97.3%～106.1%, Cmax 90% confidence interval for the reference preparation parameters corresponding to 90.0%～100.7%.Test preparation and the reference preparation pharmacokinetic parameters of multi-dose Tmax were 6.05±2.16 and 6.25±2.07 h; Cmax were 87.54±51.33 and 88.26±52.68 ng·ml-1, t1/2 were 12.15±3.67 and 12.03±3.10 h; Cav were 55.96±42.66 and 55.02±39.37 ng·ml-1, DF were 116.39±43.73 and 112.3±36.3, AUCSS were 1343.02±1023.81 and 1320.58±944.97 ng·h·ml-1. AUCSS in terms of soft gelatin capsules venlafaxine relative bioavailability of an average of 100.8±12.6%.Evaluation of bioequivalence was made by analysis of variance and confidence interval method. The results show that the tested agents, the AUCSS venlafaxine 90% confidence interval for the reference preparation of the corresponding parameters of 95.1%～105.2%, Cmax 90% confidence interval for the reference preparation parameters corresponding to 95.2%～107.8%.ConclusionThe method is simple, rapid and accurate.It was suitable for determination of drug concentration of venlafaxine in human plasma. The bioequivalence of the two formulations may be convicted based on the above results.