Somogyi A, Keal J, Bochner F
Department of Clinical and Experimental Pharmacology, University of Adelaide, Australia.
Ther Drug Monit. 1988;10(4):463-8. doi: 10.1097/00007691-198804000-00015.
The paucity of data on disposition of the potassium-retaining diuretic amiloride is mainly owing to the lack of sensitive and specific analytic methods for measuring the drug in biologic fluids. Poor lipophilicity and extremely low plasma concentrations impose severe constraints. A method is described for analysing plasma and urine concentrations of amiloride using an ion-pair extraction method and high-performance liquid chromatography (HPLC) with fluorescence detection. Amiloride and internal standard triamterene form an ion-pair with bromothymol blue at pH 7.6. The ion-pairs are extracted into diethyl ether: dichloromethane (2:1), and back-extraction into 0.1% tetrabutylammonium hydroxide liberates the drugs from their ion pairs. Analyses are performed using HPLC with a reverse-phase C18 column and a mobile phase of 11% acetonitrile and 0.5% triethylamine adjusted to pH 3. Amiloride is quantified using fluorescence detection (366-nm excitation, 418-nm emission cutoff). Retention times are 2.2 and 6.0 min for amiloride and triamterene, respectively. The sensitivity limit is 0.2 ng/ml, and recovery is 82% for amiloride and 71% for triamterene. Calibration curves are linear (range 0.25-25 ng/ml for plasma and 0.05-2.0 micrograms/ml for urine). Inter- and intraday assay variability is less than 8% and precision is within 5%. The assay is of sufficient sensitivity and specificity for the study of the pharmacokinetics of amiloride in humans.
关于保钾利尿剂阿米洛利处置的数据匮乏，主要是由于缺乏用于测量生物体液中该药物的灵敏且特异的分析方法。其亲脂性差和血浆浓度极低带来了严重限制。本文描述了一种使用离子对萃取法和带荧光检测的高效液相色谱法（HPLC）分析阿米洛利血浆和尿液浓度的方法。在pH 7.6条件下，阿米洛利和内标氨苯蝶啶与溴百里酚蓝形成离子对。离子对被萃取到乙醚：二氯甲烷（2:1）中，再用0.1%氢氧化四丁铵反萃取，使药物从离子对中释放出来。使用HPLC进行分析，采用反相C18柱，流动相为11%乙腈和0.5%三乙胺，pH值调至3。阿米洛利用荧光检测进行定量（激发波长366 nm，发射截止波长418 nm）。阿米洛利和氨苯蝶啶的保留时间分别为2.2分钟和6.0分钟。灵敏度极限为0.2 ng/ml，阿米洛利的回收率为82%，氨苯蝶啶的回收率为71%。校准曲线呈线性（血浆范围为0.25 - 25 ng/ml，尿液范围为0.05 - 2.0 μg/ml）。日内和日间测定变异小于8%，精密度在5%以内。该测定方法对研究人类体内阿米洛利的药代动力学具有足够的灵敏度和特异性。
