Tikkanen Frej Fyhrquist Ilkka, Grönhagen-Riska Carola
a From the Unit of Clinical Physiology , Minerva Institute for Medical Research , P.O. Box 819, SF - 00101 Helsinki 10 , Finland and the IVth Department of Medicine , University of Helsinki.
Scand J Urol Nephrol. 1984 Jul;18(sup79):13-16. doi: 10.1080/00365599.1984.11783708.
We developed a novel assay method for the determination of captopril and enalapril serum concentrations. This method is based on a new principle of enzyme assay, inhibitor binding assay (IBA), recently introduced by us for the measurement of serum angiotensin converting enzyme (ACE). The assay principle is based on binding of I-labelled ACE inhibitor (351A, p-hydroxy-benzamidine derivative of N-(1-carboxy-3-phenylpropyl)-L-lysyl-L-proline) to ACE. A competitive IBA was established using captopril as a standard and human serum ACE as a binder. For the assay of captive captopril, 0.1 ml of venous blood was taken into 9.9 ml of ice-cold buffer. Following separation of cells, the supernatant was stored at -20°C until assayed. Tubes containing added serum ACE as a binder, labelled inhibitor, and unknown samples, were incubated for 1 hour at 37°C. Following separation of bound label the content of captopril was read from a standard curve. Results in healthy subjects showed peak blood concentrations ranging from 220 to 1300 ng/ml within 30-60 minutes after a single oral dose of 50 mg captopril, and virtual disappearence of active drug from the blood within 3 hours. About 50 % of the measurable active captopril was lost during storage of diluted plasma for one month at -20°C The assay method is simple and sensitve, and measures active drug only. The present new assay principle may prove convenient and feasible for the assay of captopril and other ACE inhibitors in biological fluids.
我们开发了一种用于测定卡托普利和依那普利血清浓度的新检测方法。该方法基于一种新的酶检测原理，即抑制剂结合检测法（IBA），这是我们最近为测量血清血管紧张素转换酶（ACE）而引入的。检测原理基于I标记的ACE抑制剂（351A，N-(1-羧基-3-苯基丙基)-L-赖氨酰-L-脯氨酸的对羟基苯甲脒衍生物）与ACE的结合。以卡托普利为标准品，人血清ACE为结合剂，建立了竞争性IBA。对于卡托普利的检测，取0.1 ml静脉血加入9.9 ml冰冷缓冲液中。细胞分离后，将上清液储存在-20°C直至检测。含有添加的血清ACE作为结合剂、标记抑制剂和未知样品的试管在37°C孵育1小时。结合标记物分离后，从标准曲线读取卡托普利的含量。健康受试者的结果显示，单次口服50 mg卡托普利后30 - 60分钟内，血药浓度峰值范围为220至1300 ng/ml，3小时内血液中的活性药物几乎消失。在-20°C下将稀释血浆储存一个月期间，约50%可检测到的活性卡托普利会损失。该检测方法简单且灵敏，仅测量活性药物。目前这种新的检测原理可能被证明对于生物流体中卡托普利和其他ACE抑制剂的检测方便且可行。
