Paeoniae Radix,a traditional Chinese medicine,and CYP2C9 activity

Paeoniae Radix (PR) is a commonly used traditional Chinese medicine. A slight effect of PR on the pharmacokinetics of phenytoin that is mainly metabolised by CYP2C9 has been reported. The aim of this pilot study was to clarify if PR has an effect on losartan oxidation used as a measure of CYP2C9 activity. Three healthy volunteers received a single oral dose of losartan before and after PR treatment. Losartan and E-3174, an active metabolite of losartan, were analysed in 8 hour urine. PR did not seem to have an effect on CYP2C9 activity when the losartan/E-3174 ratios were compared before and after PR treatment (P = 0.56) although a larger study would need to be undertaken to confirm this finding.     

Pathologic consequences of increased angiotensin II activity

Summary Advances in molecular medicine and pharmacology have allowed clinicians to critically reassess the reninangiotensin system. Angiotensin II (AII) participates in the control of cardiovascular function and electrolyte balance, and plays a part in the regulation of cellular oncogenes and the expression of growth factors. The expression of the proteins of the renin-angiotensin system in organs other than the kidneys suggests that these diverse actions are associated with the peptide in the local environment. Tissue reninangiotensin activity has prompted the investigation of alternate pathways for the production of AII and characterization of novel forms of angiotensin peptides that counteract the vasoconstrictor and proliferative actions of AII. The heptapeptide angiotensin-(1–7) appears to be critically involved in regulating the angiotensinogen activity of AII through stimulation of vasodilator prostaglandins and release of nitric oxide. Study in this area has been accelerated by the identification of receptors that convey the actions of angiotensin peptides at the cellular level and the pharmacologic characterization of agents that inhibit the ability of AII to bind to target receptors. The introduction of a new class of orally active AII-receptor blockers has provided a specific test of the role of AII in the development of essential hypertension and the potential for improved therapy for hypertension and cardiac and vascular sequelae.     

Pioglitazone and Losartan Modify Hemodynamic and Metabolic Parameters and Vascular Prostanoids in Fructose-Overloaded Rats

This study analyzes the effects of losartan (AT1 blocker) and pioglitazone (insulin sensitizer), alone and in combination, in the fructose-overloaded rat, a model of metabolic syndrome. All treatments (nine weeks) reduced blood pressure and triglyceridemia and also restored the diminished release of vasodilator prostaglandins (prostacyclin in aorta and mesenteric vascular bed and prostaglandin E₂ in the latter). Pioglitazone, alone and in combination with losartan, reduced the release of the vasoconstrictor thromboxane in controls and fructose rats in both vascular preparations. In conclusion, although combination therapy and single treatments exerted similar effects, there may still be some advantage to the combined treatment.     

In vitro pharmacological characterization of UP 269-6, a novel nonpeptide angiotensin II receptor antagonist

Summary— The in vitro pharmacology of UP 269-6, a novel nonpeptide angiotensin II antagonist, was examined in radioligand binding and functional isolated tissue assays. UP 269-6 bound selectively to AT₁ receptors as evidenced by the inhibition of specific [¹²⁵I] Sar¹, Ile⁸-AII binding in rat adrenal membranes (IC₅₀ = 35.8 nM) and in cultured vascular smooth muscle cells (IC₅₀ = 23.8 nM). UP 269-6 displayed a very high selectivity for the AT₁ compared to the AT₂ receptor subtype (IC₅₀ > 10,000 nM). UP 269-6 inhibited the AII-induced contraction of isolated rabbit aortic strips. The pattern of AII antagonism suggested competitive antagonism at low concentrations (10⁻¹⁰, 3 × 10⁻¹⁰, 10⁻⁹ M) of UP 269-6 and insurmountable antagonism at higher concentrations (3 × 10⁻⁹, 10⁻⁸, 3 × 10⁻⁸ M). Based on the calculated p A₂ values, UP 269-6 (9.86 ± 0.25) was an angiotensin II receptor antagonist as potent as L-158,809 (9.82 ± 0.37) and much more potent than losartan (7.96 ± 0.38). UP 269-6 was devoid of affinity (IC₅₀ > 10,000 nM) for many other receptors, ion channels and uptake sites, demonstrating its high specificity for AII receptors. Furthermore, this compound did not affect the contractile response to KCl or phenylephrine in rabbit aorta and exhibited no effect on angiotensin converting enzyme activity. These data demonstrate that UP 269-6 is a highly potent, selective and specific AT₁ receptor antagonist.     

Spectrophotometric and HPLC Methods for Simultaneous Estimation of Amlodipine Besilate, Losartan Potassium and Hydrochlorothiazide in Tablets

Two UV-spectrophotometric and one reverse phase high performance liquid chromatography methods have been developed for the simultaneous estimation of amlodipine besilate, losartan potassium and hydrochlorothiazide in tablet dosage form. The first UV spectrophotometric method was a determination using the simultaneous equation method at 236.5, 254 and 271 nm over the concentration range 5-25, 10-50 and 5-25 μg/ml for amlodipine besilate, losartan potassium and hydrochlorothiazide, respectively. The second UV method was a determination using the area under curve method at 231.5-241.5, 249-259 and 266-276 nm over the concentration range of 5-25, 5-25 and 10-50 μg/ml for amlodipine besilate, hydrochlorothiazide and losartan potassium, respectively. In reverse phase high performance liquid chromatography analysis is carried out using 0.025 M phosphate buffer (pH 3.7):acetonitrile (57:43 v/v) as the mobile phase and Kromasil C18 (4.6 mm i.d×250 mm) column as stationery phase with detection wavelength of 232 nm linearity was obtained in the concentration range of 2-14, 20-140 and 5-40 μg/ml for amlodipine besilate, losartan potassium and hydrochlorothiazide, respectively. Both UV-spectrophotometric and reverse phase high performance liquid chromatography methods were statistically validated and can be used for analysis of combined dose tablet formulation containing amlodipine besilate, losartan potassium and hydrochlorothiazide.     

氯沙坦对大鼠脑缺血再灌注损伤的保护作用及分子机制

目的研究氯沙坦对大鼠脑缺血再灌注(IR)损伤的保护作用及分子机制。方法 80只成年雄性SD大鼠随机分为假手术组、IR组、2. 5 mg/kg氯沙坦组、5. 0 mg/kg氯沙坦组、5. 0 mg/kg氯沙坦+LY组。2. 5 mg/kg氯沙坦组、5. 0 mg/kg氯沙坦组、5. 0 mg/kg氯沙坦+LY组在造模前连续给予氯沙坦灌胃干预14天,5. 0 mg/kg氯沙坦+LY组在造模前30 min给予磷脂酰肌醇3激酶(PI3K)抑制剂LY294002侧脑室注射。采用线栓法建立大鼠脑IR损伤模型,在再灌注后24 h评价神经功能缺损并测定脑组织含水量、细胞凋亡情况、凋亡相关基因表达水平。结果与假手术组比较,IR组大鼠的脑组织含水量、神经功能缺损评分、TUNEL阳性率及脑组织中Bcl-2相关X蛋白(Bax)/GAPDH、细胞色素C(Cyt C)/GAPDH、Cleaved-caspase-3/Pro-caspase-3的水平均显著增加,脑组织中B淋巴细胞瘤2蛋白(Bcl-2)/GAPDH、p-PI3K/PI3K、p-AKT/AKT的水平显著减少;与IR组比较,2. 5 mg/kg氯沙坦组和5. 0 mg/kg氯沙坦组大鼠的脑组织含水量、神经功能缺损评分、TUNEL阳性率及脑组织中Bax/GAPDH、Cyt C/GAPDH、Cleaved-caspase-3/Pro-caspase-3的水平均显著减少,脑组织中Bcl-2/GAPDH、p-PI3K/PI3K、p-AKT/AKT的水平显著增加;与5. 0 mg/kg氯沙坦组比较,5. 0 mg/kg氯沙坦+LY组大鼠的脑组织含水量、神经功能缺损评分、TUNEL阳性率及脑组织中Bax/GAPDH、Cyt C/GAPDH、Cleaved-caspase-3/Pro-caspase-3的水平均显著增加,脑组织中Bcl-2/GAPDH、p-PI3K/PI3K、p-AKT/AKT的水平显著减少。结论氯沙坦通过上调PI3K/AKT通路减轻大鼠脑IR损伤。     

洛沙坦和苯那普利治疗肾性高血压的临床疗效对比

目的　探讨洛沙坦 (氯沙坦 )和苯那普利单用、联合治疗肾性高血压的临床效果。方法　对 30例单用洛沙坦 (A组 )和 2 7例单用苯那普利 (B组 )及 30例联合治疗患者 (C组 )比较 ,观察其治疗前后血压、2 4小时尿蛋白、血肌酐、肝功能、血脂的变化及不良反应。结果　 3组治疗后 2周血压较治疗前即有所下降 ,联合用药组 2～ 4周明显下降 (P <0 .0 5 ) ,单独用药的两组 4周后血压才明显下降 (P <0 .0 5 )。联合用药组血肌酐 (Cr)第 1 2周时有明显下降(P <0 .0 5 ) ,单独用药的两组Cr无明显下降 (P >0 .0 5 )。 3组治疗前后尿蛋白均有明显减少 (P <0 .0 5 ) ,单独用药的两组尿蛋白降低程度差异无统计学意义 (P >0 .0 5 ) ,联合用药组尿蛋白降低程度与单独用药的两组比较差异有统计学意义 (P <0 .0 5 )。 3组治疗前后肝功能、血脂无明显变化 ,洛沙坦组无明显不良反应。结论　洛沙坦和苯那普利联合治疗肾性高血压较单独使用更能有效控制血压 ,减少蛋白尿 ,降低血肌酐     

氯沙坦对高血压患者24h动态血压的影响

采用动态血压监测 (ABPM)法比较 3 0例轻中度高血压病患者经氯沙坦 (5 0mg/d)治疗 4周后 2 4h平均血压、白昼及夜间平均血压、心率、血压负荷、夜间下降率等的变化 ,并与诊室血压 (CBP)相比较。治疗 4周末 ,CBP、2 4h平均血压、白昼及夜间平均血压、血压负荷均有显著降低 ,心率无显著改变。CBP示 4周末总有效率为 70 .0 %。各时点血压均较治疗前下降 ,对夜间血压的影响略小 ,但血压昼夜节律无显著改变。降压疗效谷 /峰比大于 70 %。提示 :氯沙坦能安全有效地降低血压 ,维持正常的血压昼夜节律 ,尤适于夜间血压低的杓型高血压患者。     

氯沙坦及其代谢物在汉族健康人体内药动学研究

 目的 研究氯沙坦及其代谢产物2-丁基-4-氯-1-[[2’-(1H-四唑-5-基）[1,1‘-联苯基]-4-基]甲基]-lH一咪唑-5-羧酸（E-3174）在中国汉族健康受试者体内的药动学。方法 10名健康受试者,男女各半,口服氯沙坦钾片50 mg,定时采血,用HPLC荧光法测定氯沙坦及其代谢物E-3174血药浓度,DAS2.0软件程序进行数据处理并采用SPSS13.0软件进行统计学分析。结果 氯沙坦和E-3174的主要药动学参数如下：ρ_max分别为( 351±167),( 241±60) μg·L^-1; t_max分别为(1.35±1.06),(3.60±1.68) h;t1/2分别为(0.82±0.40),(4.66±1.10) h;AUC_0-24分别为(498±172),(1 853±194) μg ·h·L^-1;AUC_0-∞分别为(523±184),(1 960±182) μg ·h·L^-1。结论 氯沙坦及其代谢物E-3174的药动学特征和参数在个体间存在较大差异,临床治疗中应实行个体化给药方案。