LC-MS/MS determination of glimepiride in human plasma with a high recovery at picogram scale: Pharmacokinetic study after oral administration

Although glimepiride (GLM) is the first-line treatment of Type II diabetes, low extraction recovery is still a significant limitation in previous plasma analysis methods. An optimized solid-phase extraction method of GLM in human plasma with excellent extraction recovery, 100 ± 0.06%, was achieved using liquid chromatography-electrospray ionization tandem mass spectrometry and Gliclazide (GLZ) as an internal standard. GLM was extracted from 100 µL plasma sample using Sep-Pak® vac 1cc (100 mg) C18 column and methylene chloride: methanol (2: 1, v/v) as eluant. Both GLM and GLZ were monitored by a triple quad mass spectrometer applying positive multiple reaction monitoring mode (+MRM). The protonated precursor ions and product ions of GLM and GLZ were m/z 491(352), and m/z 324 (127), respectively. The detection and measurement of low levels of GLM in human plasma reached to picogram range (limit of detection (LOD) = 60 pg/mL, limit of quantification (LOQ) = 200 pg/mL). The method was validated in terms of selectivity, linearity, recovery, accuracy, and precision. The method was successfully applied to the pharmacokinetic study of GLM following oral administration of 1 mg GLM tablets to 12 healthy volunteers.