Quantitation of urapidil and its metabolites in human serum by high performance liquid chromatography

The antihypertensive agent urapidil (Ebrantil Byk-Gulden, Konstanz) can be reliably quantitated with three metabolites in human serum using high performance liquid chromatography. Serum is alkalinized and extracted with ethyl acetate. The organic phase is back-extracted with diluted acid. An aliquot is sampled automatically and chromatographed in an optimized combination of mobile and stationary phase. UV-detection at 273 nm allows a quantitation limit of 5 ng/ml for all analytes. Precise handling of exact volumes facilitates external calibration. The coefficient of variation for spiked samples is less than 5% within and less than 7% between studies. Application of the method to experimental and clinical pharmacokinetic studies of urapidil is illustrated.     

HPLC in pharmacokinetics and metabolism studies

Summary The use of high-performance liquid chromatography in kinetics and metabolism studies is demonstrated.The following kinetic parameters are ascertained after single oral and intravenous administration of a drug: absorption by areal comparison, elimination constant in the -phase, and clearance.Concentration levels in serum are measured after repeated oral administration on several days, with pharmacokinetic model fit to estimate limit concentrations in the steady state. Species-dependencies in metabolism are investigated in 24-h urines.The necessary characterization of drug and metabolite peaks is obtained by in-series connection of several detectors.The relative bioavailability of a controlled release form is determined by measuring drug concentrations in the blood.     

乌拉地尔的荧光光谱研究及测定

建立了一种测定制剂中乌拉地尔的荧光分光光度法。用荧光分光光度法研究了不同溶剂和pH下乌拉地尔的荧光光谱性质。在pH5.0缓冲溶液中,在3.30×10-7～1.65×10-5mol/L浓度范围内,285nm紫外光的激发下,乌拉地尔在365nm处的荧光强度与浓度呈良好的线性关系。线性相关系数为0 9975,测定片剂和针剂的平均回收率分别为99.0%和99.8%,相对标准偏差小于3 0%。     

流动注射-间接原子吸收法测定乌拉地尔

研究了乌拉地尔、Bi(Ⅲ)和KI形成的离子缔合物的性质，提出了流动注射-间接原子吸收法(FI-AAS)分析乌拉地尔的新方法。它是基于乌拉地尔在适当的酸度条件下与BiI4^-反应生成不溶于水的离子缔合物，经流动注射在线过滤稀释，以AAS法测定反应后剩余铋的量来间接测定乌拉地尔的含量。本文对原子吸收、流动注射的工作条件进行了优化，并使用内填微孔滤膜的柱形过滤器收集沉淀，使灵敏度大为提高。乌拉地尔的质量浓度在5-100μg／mL范围内与吸收值呈良好的线性关系，回收率为97.2％-100.8％，采样频率为100次／h。     

流动注射-化学发光法测定乌拉地尔

乌拉地尔 (Urapidil)即 6 - { [3 - [4- (o-甲氧苯基 ) - 1 -哌嗪 ]-丙基 ]-氨基 } - 1 ,3 -二甲基脲嘧啶 ,又名乌Scheme 1　 The chemical structure of Urapidil拉尔碱或压宁定 ,为苯哌嗪取代的脲嘧啶衍生物 ,其结构见 Scheme 1 .乌拉地尔是一种高选择性的α受体阻滞剂 ,能使     

Voltammetric behavior of urapidil and its determination at multi-wall carbon nanotube paste electrode

The voltammetric behavior of urapidil was investigated. In pH 6.8 Britton-Robinson buffer, an irreversible oxidation peak of urapidil at 0.62 V (versus SCE) at a multi-wall carbon nanotube paste electrode (MWNT-PE) was observed, which was more sensitive with lower potential than that at the carbon paste electrode (CPE). The oxidation of urapidil was a two-electron and two-proton process with adsorption character. A differential pulse voltammetric method was proposed for the determination of urapidil. The peak current of the oxidation peak of urapidil was linearly with its concentration in a range from 5.0 × 10⁻⁸ to 2.0 × 10⁻⁶ mol/L at open-circuit accumulation for 60 s, with a detection limit of 3.8 × 10⁻⁸ mol/L. The proposed method was employed to determine urapidil in urapidil tablets.     

新药乌拉地尔含量的高效液相色谱法测定

用高效液相色谱法测定乌拉地尔（urapidil)的含量。采用PhenomenexLUNA C18柱;1％（φ）冰醋酸溶液－甲醇（体积比50：50）为流动相;检测波长为268nm;外标法定量测定,结果显示样品质量浓度在10－200nm/L范围内与峰面积呈良好线性关系,相关系数为0．9999（n-5);平均加标回收率为99．8％。该法操作快捷,重复性好,结果准确可靠,可用于乌拉地尔的质量控制。