Gupta S K, Ellinwood E H
Department of Psychiatry, Duke University Medical Center, Durham, NC 27710.
J Pharm Sci. 1990 Sep;79(9):822-5. doi: 10.1002/jps.2600790916.
A reversed-phase high-performance liquid chromatographic method is described for simultaneous quantification of halazepam and its major active metabolite, nordiazepam, in plasma. The method uses a solid-phase extraction procedure to prepare plasma samples. After extraction, the methanolic extract is evaporated, and the residue is then reconstituted in a small volume of mobile phase (a 40:60, v/v, mixture of 0.02 M phosphate buffer, pH 4.0, and methanol) and chromatographed. The total chromatography time for a single sample is approximately 10 min. A sensitivity of 1 ng/mL for halazepam and nordiazepam is attained when 1 mL of plasma is extracted. Analytical recovery of halazepam and nordiazepam added to the plasma ranged from 89 to 96%. The maximum within-day and day-to-day coefficients of variation for each compound at the concentration range of 2 to 100 ng/mL were 8.7 and 10.3%, respectively. Suitability of the method was assessed in a preliminary pharmacokinetic study in which three subjects were given a single 20-mg oral dose of halazepam following an overnight fast. It appeared from our kinetic analysis that halazepam is a drug with a fairly rapid absorption phase that is followed by a slow elimination phase. Mean oral plasma clearance of halazepam was 24 L/h. The mean apparent elimination half-life of nordiazepam (45.22 h) is considerably longer than that of halazepam (21.15 h).
本文描述了一种反相高效液相色谱法，用于同时定量测定血浆中的哈拉西泮及其主要活性代谢物去甲西泮。该方法采用固相萃取程序制备血浆样品。萃取后，将甲醇提取物蒸发，然后将残渣用少量流动相（0.02 M pH 4.0的磷酸盐缓冲液和甲醇按40:60，v/v混合）复溶并进行色谱分析。单个样品的总色谱分析时间约为10分钟。当萃取1 mL血浆时，哈拉西泮和去甲西泮的灵敏度达到1 ng/mL。添加到血浆中的哈拉西泮和去甲西泮的分析回收率在89%至96%之间。在2至100 ng/mL浓度范围内，每种化合物的日内和日间最大变异系数分别为8.7%和10.3%。在一项初步药代动力学研究中评估了该方法的适用性，该研究中三名受试者在禁食过夜后单次口服20 mg哈拉西泮。从我们的动力学分析来看，哈拉西泮是一种吸收相相当快、随后消除相缓慢的药物。哈拉西泮的平均口服血浆清除率为24 L/h。去甲西泮的平均表观消除半衰期（45.22小时）比哈拉西泮（21.15小时）长得多。
