Matar Kamal M
Department of Applied Therapeutics, Faculty of Pharmacy, Kuwait University, Safat, Kuwait.
J Pharm Biomed Anal. 2008 Nov 4;48(3):822-8. doi: 10.1016/j.jpba.2008.05.035. Epub 2008 Jun 3.
A rapid, selective, reliable, precise, accurate, and reproducible tandem mass spectrometric (MS-MS) method for the quantification of levetiracetam (LEV) in human plasma using adenosine as an internal standard (IS) has been developed and validated. The drug and IS were extracted by solid phase extraction (SPE) technique and analyzed on Symmetry((R)) C(18) column (5 microm, 3.9 mm x 50 mm) using a mobile phase of methanol-water-formic acid (97:03:0.25, v/v/v) at a flow rate of 0.2 ml/min. Quantitation was achieved using a positive electrospray ionization (ESI+) interface employing multiple reaction monitoring (MRM) mode at MRM transitions m/z 171>126 and m/z 268>136 for LEV and IS, respectively. The method was validated over the concentration range of 1.0-40 microg/ml (r>0.99) with a limit of quantification of 1.0 microg/ml (R.S.D.%; 4.1 and Bias%; -9.0 to + 11.0%). Intra- and inter-run precision of LEV assay at three concentrations ranged from 0.6 to 8.9% with accuracy (bias) varied from -4.0 to 8.6% indicating good precision and accuracy. Analytical recoveries of LEV and IS from spiked human plasma were in the range of 91.7-93.4% and 80.2-84.1%, respectively. Stability of LEV in human plasma samples at different conditions showed that the drug was stable under the studied conditions. Matrix effect study showed a lack of matrix effect on mass ions of LEV and IS. The described method compared well with the commercial HPLC-UV method of Chromsystem (r(2)=0.99). The suitability of the developed method for therapeutic drug monitoring was demonstrated by measuring LEV in human plasma samples of epileptic patients treated with LEV.
已开发并验证了一种快速、选择性好、可靠、精确、准确且可重现的串联质谱（MS-MS）方法，用于以腺苷作为内标（IS）定量测定人血浆中的左乙拉西坦（LEV）。采用固相萃取（SPE）技术提取药物和内标，并在Symmetry((R)) C(18) 柱（5μm，3.9mm×50mm）上进行分析，流动相为甲醇 - 水 - 甲酸（97:03:0.25，v/v/v），流速为0.2ml/min。使用正电喷雾电离（ESI +）接口，采用多反应监测（MRM）模式进行定量，LEV和内标的MRM跃迁分别为m/z 171>126和m/z 268>136。该方法在1.0 - 40μg/ml的浓度范围内进行了验证（r>0.99），定量限为1.0μg/ml（相对标准偏差%；4.1，偏差%；-9.0至 + 11.0%）。在三个浓度下，LEV测定的批内和批间精密度范围为0.6%至8.9%，准确度（偏差）在 - 4.0%至8.6%之间，表明精密度和准确度良好。从加标的人血浆中回收LEV和内标的分析回收率分别在91.7 - 93.4%和80.2 - 84.1%范围内。不同条件下人血浆样品中LEV的稳定性表明该药物在所研究的条件下是稳定的。基质效应研究表明，基质对LEV和内标的质量离子没有影响。所描述的方法与Chromsystem的商业HPLC-UV方法相比效果良好（r(2)=0.99）。通过测量接受LEV治疗的癫痫患者的人血浆样品中的LEV，证明了所开发方法适用于治疗药物监测。
