Compound Losartan Potassium Hydrogen Chloro-thiazide Tablets Pharmacokinetic Study

1.The pharmacokinetics of Losartan and hydrochlorothiazide in ratA sensitive and specific high-peformance liquid chromatography/electrospray ionization tandem mass spectrometric(LC/MS/MS)method was developed and validated for the quantification of losartan and hydrochlorothiazide in rat plasma.Losartan was detected in positive ionization and hydrochlorothiazide in negative ionization by multiple reactions monitoring with a mass spectrometer.The mobile phase was methanol:1%formic acid(80:20)for losartan and methanol:2%ammonia solution(90:10)for Hydroehlorothiazide,respectively.The analytes were extracted from the matrixes by liquid-liquid extraction,and then separated on a Restek Pinnacle C₁₈column.The assay exhibited good linear over the range 50-10000μg·L^-1for Losartan and 1-1000μg·L^-1for Hydrochlorothiazide in plasma.All the validation data,such as accuracy,precision,and inter-day repeatability,were within the required limits.Dose of 13/3.25,26/6.5,52/13 mg·kg^-1were administrated to 3-dose group male rats by i.g. There had a maximal plasma concentration of losartan between 0.50～1.17h,and the ratio between C_max,AUC_0-tand dose(P＜0.05)had a linear correlation.The ratio of AUC_0-tand dose had insignificant difference after analysis of variance(P＞0.05),which showed that the process of losartan in rats conformed with linear pharmacokinetics;there had a maximal plasma concentration of hydrochlorothiazide between 1.00～1.50h,and the ratio between C_max,AUC_0-t and dose(P＜0.05)had a linear correlation.The ratio of AUC_0-tand dose had insignificant difference after analysis of variance(P＞0.05),which showed that the process of hydrochlorothiazide in rats does not conformed with linear pharmacokinetics.Losartan and hydrochlorothiazide distributed rapidly in tissues after absorbing into plasma. The concentration of losartan in stomach and intestine were highest,next liver,kidney,spleen, lung,heart,and that in stomach and intestine was more 200times than that in plasma.The t_1/2in stomach,intestine,lung,heart and spleen showed that losartan was not accumulated in tissues. The ratio of AUC_0-tin tissues and AUC_0-tin plasma indicated that distribution in stomach and intestine were the widest.;the concentration of hydrochlorothiazide in stomach and intestine were highest,next liver,kidney,spleen,lung,heart,and that in stomach and intestine was more 20 times than that in plasma,respectively.The t_1/2in stomach,intestine,lung,heart and spleen showed that hydrochlorothiazide was not accumulated in tissues.The ratio of AUC_0-tin tissues and AUC_0-tin plasma indicated that distribution in stomach and intestines were the widest. 2.The pharmacokinetics and bioavailability of Losartan and hydrochlorothiazide in humanA HPLC-MS/MS method has been established for determination losartan and hydrochlorothiazide concentration in human plasma.Losartan was detected in positive ionization and hydrochlorothiazide in negative ionization by multiple reactions monitoring with a mass spectrometer.The mobile phase was methanol:1%formic acid(90:10)for Losartan and acetiontlile:2%ammonia solution(90:10)for Hydrochlorothiazide,respectively.The analytes were extracted from the matrixes by liquid-liquid extraction,and then separated on a Zorbax Eclipse C₁₈column.The assay exhibited good linear over the range 5-400μg·L^-1for Losartan and 1-100μg·L^-1for hydrochlorothiazide.All the validation data,such as accuracy,precision,and inter-day repeatability,were within the required limits.A single oral dose of 50mg Losartan and 12.5mg hydrochlorothiazide test and reference preparations were administrated to 20 healthy volunteers in a randomized cross-over design to study pharmacokinetics and relative bioavailability of Losartan and hydrochlorothiazide tablets in healthy male volunteers.Plasma concentration of Losartan and hydrochlorothiazide was determined by HPLC-MS/MS method,and pharmacokinetics and relative bioavailability were evaluated by DAS 2.0.Main pharmacokinetic parameters of losartan for single dose were as follows:T_maxwere 1.09±0.56 and 1.12±0.55h;C_maxwere118.9±68.9 and 110.2±51.0μg·L^-1; t_1/2were 3.15±0.76 and 2.96±0.71 h;for the test and reference drugs,respectively.The relative bioavailability of the test drug is 96.5±21.2%;and main pharmacokinetic parameters of hydrochlorothiazide for single dose were as follows:T_maxwere 1.93±0.54 and 2.25±0.60h; C_maxwere73.2±11.0 and 74.5±17.4μg·L^-1;t_1/2were 9.45±3.57 and 8.33±2.58 h;for the test and reference drugs,respectively.The relative bioavailability of the test drug is 106.8±22.9%.The main pharmacokinetic parameters were analyzed by ANOVA after log transformation. It showed that AUC_0-t,AUC_0-∞and C_maxfor the test and reference drugs of Losartan and hydrochlorothiazide has no significant difference in preparations and periods,and has significant difference between individual.Adopted two one-side test and(1-2α)confidential interval test, AUC_0-t,AUC_0-∞and C_maxof test preparation both rejection the assumption of inequivalence. AUC_0-tof testpreparation was 86.0～113.5%of reference preparation by 90%confidence interval test.So the test and reference preparations were bioequivalence.