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Simultaneous determination of ezetimibe, atorvastatin and simvastatin using quadrupole LC-MS: Application to combined tablets and plasma after SPE

100%

Elawady T. , Ibrahim F. , Khedr A. , Belal F.

Acta Chromatographica

2021

tom Vol. 33, no. 3

245--252

A simple and sensitive liquid chromatography-mass spectrometric (LC-MS) method has been developed and validated for the simultaneous determination of ezetimibe (EZE), atorvastatin calcium (ATO), and simvastatin (SMV) in combined dosage forms and human plasma. Successful separation of the studied drugs was achieved on a Zorbax Eclipse Plus C18 column (3.0 × 150 mm, 5 µm) using a mobile phase consisting of acetonitrile and 0.1% formic acid in water (65:35, v/v) at a flow rate of 0.5 mL min-1. Total run time was 9.3 min and diclofenac sodium was used as internal standard (IS). Positive selected ion monitoring (SIM) mode was applied where, the monitored ions were those at m/z values of 392.1, 559.3, 296.0, and 441.4 corresponding to EZE, ATO, IS, and SMV, respectively. The method was fully validated according to the ICH guidelines. The intraday and interday precision showed relative SD values not more than 1.77 and 1.99%; respectively. The limits of detection (LOD) were 0.25, 0.25, and 0.75 ng mL-1 while the limits of quantification (LOQ) were 1.25, 0.75, and 2.5 ng mL-1 for EZE, ATO, and SMV, respectively. The developed method was applied on two types of combined tablets concerning drug assay with mean percent recoveries within acceptable range. The method has been extended to the determination of the studied drugs in human plasma where, a solid phase extraction method was optimized for their extraction with percent recovery not less than 97%.

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

88%

Kammoun A. K. , Awan Z. A. , Elawady T. , Khedr A. , El-Awady M. I.

Acta Chromatographica

2022

tom Vol. 34, no. 1

12--17

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.