Ojha Ashwini, Rathod Rajeshwari, Padh Harish
Patel Pharmaceutical Education, Research and Development Centre (PERD), S-G Highway, Thaltej, Ahmedabad, Gujarat, India.
Bioanalysis. 2009 May;1(2):293-8. doi: 10.4155/bio.09.26.
Dipyrone (metamizole) is a nonsteroidal anti-inflammatory drug used as an analgesic and antipyretic in both pediatric and adult patients. Dipyrone hydrolyses to 4-methylaminoantipyrine (MAA) in the stomach before absorption. There are several HPLC methods available for analysis of MAA from human plasma but no method has yet been developed on liquid chromatography-mass spectrometry (LC-MS) or LC tandem MS (LC-MS/MS), which are much more specific and sensitive techniques.
A high-performance LC-MS method for the quantification of 4-methylaminoantipyrine from human plasma has been developed, validated and applied to a pharmacokinetic study of 500 mg oral dose dipyrone. Following liquid-liquid extraction, the analyte was first separated on a reverse phase column using isocratic mobile phase and then analyzed by MS in selected ion monitoring mode using M+H ions, m/z 218.2 for 4-methylaminoantipyrine and 231.3 for 4-isopropylantipyrine (internal standard).
The method exhibited a linear range from 0.2 to 10.0 µg/ml when only 100 µl human plasma sample was used. The lower limit of detection was 0.04 µg/ml (160 pg on column). The recovery was 80%. The accuracy and precision were obtained over the calibration curve range and were well within the limits specified under guidelines for bioanalytical method validation. The compound was stable under the experimental conditions.
The method was demonstrated to be, simple, sensitive and rapid. It can be easily adopted in laboratories with access to LC-MS or MS/MS and applied to sample analysis in clinical settings where a large number of samples are generated.
安乃近是一种非甾体抗炎药，在儿科和成年患者中用作镇痛药和解热药。安乃近在吸收前于胃中水解为4-甲基氨基安替比林（MAA）。有几种高效液相色谱法可用于分析人血浆中的MAA，但尚未开发出液相色谱-质谱联用（LC-MS）或液相色谱串联质谱联用（LC-MS/MS）方法，而后者是特异性和灵敏度更高的技术。
已开发并验证了一种用于定量人血浆中4-甲基氨基安替比林的高效液相色谱-质谱联用方法，并将其应用于500 mg口服剂量安乃近的药代动力学研究。液-液萃取后，分析物首先在反相柱上使用等度流动相进行分离，然后在选择离子监测模式下通过质谱使用M+H离子进行分析，4-甲基氨基安替比林的m/z为218.2，4-异丙基安替比林（内标）的m/z为231.3。
当仅使用100 μl人血浆样品时，该方法的线性范围为0.2至10.0 μg/ml。检测下限为0.04 μg/ml（柱上160 pg）。回收率为80%。在校准曲线范围内获得了准确度和精密度，且完全在生物分析方法验证指南规定的限度内。该化合物在实验条件下稳定。
该方法证明是简单、灵敏且快速的。它可以在配备LC-MS或MS/MS的实验室中轻松采用，并应用于产生大量样品的临床环境中的样品分析。
