Lorenzo B, Drayer D E
J Lab Clin Med. 1981 Apr;97(4):545-50.
An improved method for the measurement of cimetidine in human serum by reverse-phase HPLC has been developed. The assay involves the addition of the following to 1.0 ml serum: 5 ml of ethyl acetate/isopropanol (96:4 by volume); 0.1 ml of 5N NaOH; and 0.1 ml of the internal standard, N-cyano-N'-methyl-N"-[3-(4-imidazolyl)propyl]-guanidine, which is a close structural analog of cimetidine. The extracted cimetidine is quantitated with high-pressure liquid chromatograph containing a reverse-phase column and a variable-wavelength UV detector (228 nm). The mobile phase consists of methanol in 5 mM K2HPO4 (adjusted to pH 2.8) as a 10:90 mixture by volume. At a flow rate of 2 ml/min, the retention times for the internal standard and cimetidine are 2.8 and 6.2 min, respectively. The standard curve for cimetidine is linear from 0.1 at least 4.0 micrograms/ml in serum. The CV of this assay for cimetidine, obtained from analysis of six replicate samples of a 1.0 microgram/ml serum pool, is 2%. The CV of this method obtained from the daily analysis (N = 12) of the 1.0 microgram/ml cimetidine standard, is 3%, and that from the 0.5 microgram/ml standard is 5%. Cimetidine was found to be stable in refrigerated or frozen serum for 1 month and in whole blood for 24 hr either at room temperature or refrigerated. In the serum from 13 patients receiving cimetidine therapy, the trough cimetidine levels varied from less than 0.1 to 2.7 mg/ml.
已开发出一种通过反相高效液相色谱法测定人血清中西咪替丁的改进方法。该测定方法包括向1.0 ml血清中加入以下物质：5 ml乙酸乙酯/异丙醇（体积比96:4）；0.1 ml 5N氢氧化钠；以及0.1 ml内标物N-氰基-N'-甲基-N"-[3-(4-咪唑基)丙基]-胍，它是西咪替丁的一种结构类似物。提取的西咪替丁用配备反相柱和可变波长紫外检测器（228 nm）的高压液相色谱仪进行定量。流动相由5 mM磷酸氢二钾（调至pH 2.8）中的甲醇按体积比10:90混合而成。流速为2 ml/min时，内标物和西咪替丁的保留时间分别为2.8分钟和6.2分钟。西咪替丁的标准曲线在血清中至少从0.1至4.0微克/毫升呈线性。通过对1.0微克/毫升血清池的六个重复样品进行分析得到的该西咪替丁测定方法的变异系数为2%。从1.0微克/毫升西咪替丁标准品的每日分析（N = 12）中得到的该方法的变异系数为3%，从0.5微克/毫升标准品中得到的变异系数为5%。发现西咪替丁在冷藏或冷冻血清中可稳定保存1个月，在室温或冷藏条件下的全血中可稳定保存24小时。在13名接受西咪替丁治疗的患者的血清中，西咪替丁的谷浓度在低于0.1至2.7毫克/毫升之间变化。
