Study On Pharmacokinetics Of Compound Telmisartan In Healthy Volunteers

AIM:To develop and validate a rapid and sensitive liquidchromatography/tandem mass spectrometry (LC/MS/MS) method forsimultaneous quantification of telmisartan and hydrochlorothiazide inhuman plasma. Then this method was applied in a pharmacokineticsstudy of telmisartan and hydrochlorothiazide in 9 healthy volunteers.STUDYMETHOD:Telmisartan, hydrochlorothiazide and the internalstandard (I.S.) probenecid were extracted from human plasma usingdiethyl ether-dichloromethane (60:40, v/v), and separated on a VenusilXBP-C8 column using acetate-10 mM ammonium acetate-formic acid(45:55:0.055, v/v/v). Detection was carried out by multiple reactionmonitoring (MRM) on an API 4000 LC/MS/MS system with an ESIinterface in the negative ion mode. MRM was performed at unitresolution using the mass transition ion-pairs m/z 513.0 ? m/z 469.4,m/z 295.9 ? m/z 268.9 and m/z 283.9 ? 239.9 for telmisartan,hydrochlorothiazide and I.S., respectively. The linearity, specificity,precision, accuracy, recovery and stability were estimated in the methodof validation for human plasma.According to a three-period, three-sequence, randomized crossoverdesign, the pharmacokinetics of 9 healthy male volunteers were studiedafter each was administrated by an oral dose of administration ofcompound telmisartan (containing 80 mg telmisartan and 12.5 mghydrochlorothiazide), telmisartan (80 mg) and hydrochlorothiazide (12.5mg), respectively. The concentrations of telmisartan and hydrochlorothiazide in plasma samples at different time points weredetermined by LC/MS/MS and the plasma concentrations-time profileswere obtained. The area under the curve (AUC0-t) was determined by thelinear trapezoidal rule. The terminal elimination half-life (t1/2) wasestimated with least-squares regression of values in the terminal loglinearregion of plasma concentration-time curves. Tmax and Cmax valueswere obtained directly from the observed concentrations versus time data.Other main pharmacokinetics parameters were described and estimated.The two one-sided tests procedure carried out at a significance level of0.05 were adopted to statistically study on comparison ofpharmacokinetics between the single and compound preparations oftelmisartan and hydrochlorothiazide in human volunteers.RESULTSRESULTS:A simple, rapid and sensitive LC/MS/MS method has beendeveloped and validated for the determination of telmisartan andhydrochlorothiazide in human plasma. This method was linear in theconcentration range of 1.00–600 ng/mL for both analytes with the lowerlimit of quantitation (LLOQ) of 1.00 ng/mL. In the range of the standardcurve, there is no co-eluting endogenous substances significantlyinfluenced the determination of the analytes in human plasma. Theaccuracy was in the range 92.3-112% and the intra- and inter-dayprecision was <10.6%. The sample preparation was simple and costeffective.The short-term test indicated reliable stability under theexperimental conditions of the analytical runs. The results of thefreeze/thaw stability test indicated that the analytes were stable in humanplasma for three cycles when stored at ?80°C and thawed to roomtemperature. The findings from the long-term test indicated that storageof plasma samples containing the analytes at ?80°C was adequate whenmaintained for 60 days. QC samples showed no deterioration when stored at room temperature for 6 h, since plasma samples afterextracting could be kept at room temperature for up to 6 h. Thus, nostability-related problems are expected during the routine analyses forour study. The method, which kept the conformance to the relevantstandards of Pharmacopoeia of People's Republic of China, was ideallysuited for the study of pharmacokinetics of telmisartan andhydrochlorothiazide.After oral administration of compound telmisartan or telmisartan,respectively, the Tmax values of telmisartan were 1.2 ? 0.4 (mean ? SD)and 1.2 ? 0.4 h, respectively. The Cmax values of telmisartan were 344 ?157 and 344 ? 162 ng/mL, respectively. The t1/2 values of telmisartanwere 26.1 ? 4.83 and 27.0 ? 10.1 h, respectively. The AUC0-t values were2456 ? 958 and 2239 ? 869 ng?h/mL and the AUC0-? values were 2614 ?1026 and 2392 ? 907 ng?h/mL, respectively. The MRT values were 21.5 ?3.44 and 19.4 ? 3.67 h, respectively. The CL values were 7.90 ? 1.84 and8.55 ? 1.81 mL/min/kg. The Vd values were 17.6 ? 3.83 and 19.7 ? 6.48L/kg.After oral administration of compound telmisartan or hydrochlorothiazide,respectively, the Tmax values of hydrochlorothiazide were 1.5 ? 0.3 (mean? SD) and 1.8 ? 0.6 h, respectively. The Cmax values of telmisartan were82.4 ? 26.0 and 78.9 ? 22.8 ng/mL, respectively. The t1/2 values oftelmisartan were 7.75 ? 0.95 and 7.94 ? 0.92 h, respectively. The AUC0-t values were 510 ? 122 and 493 ? 127 ng?h/mL and the AUC0-? valueswere 526 ? 121 and 510 ? 126 ng?h/mL, respectively. The MRT valueswere 7.49 ? 0.30 and 7.60 ? 1.02 h, respectively. The CL values were5.88 ? 1.37 and 6.09 ? 1.39 mL/min/kg. The Vd values were 3.97 ?1.10 and 4.18 ? 1.01 L/kg. The two one-sided tests illustrated that there was no significant differencein pharmacokinetics between the single and compound preparations oftelmisartan and hydrochlorothiazide. The results suggested that thecombination of telmisartan and hydrochlorothiazide didn't affect thepharmacokinetics action of each other in humans.