A Sensitive and Efficient Method for Determination of Capecitabine and Its Five Metabolites in Human Plasma Based on One-Step Liquid-Liquid Extraction

Abstract

Colorectal cancer is the most common critical disease both in the developed and developing countries. Capecitabine, which has served in clinical practice at least for 10 years, is a first-line antidigestive tract cancer drug for its better efficacy, patient compliance, and lower side effects. An ultra-high-performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS) method has been developed and completely validated for simultaneous determination of capecitabine and its five metabolites in human plasma from colorectal cancer patients after administration of capecitabine tablet. One-step liquid-liquid extraction was successfully applied using ethyl acetate and isopropanol (19 : 1, V : V) for sample pretreatment. Chromatographic separation was achieved within 5 min based on an Atlantis T3-C18 column (3.0 µm, 2.1 × 100 mm) with gradient elution using mobile phases consisting of 0.0075% formic acid in water (pH 4) and in acetonitrile, and the flow rate was 0.3 mL/min. Linear range was approximately 20.0–5000.0 ng/mL for all analytes. Linear correlation coefficients were >0.99 for all regression curves. The intraday and interday accuracy and precision of the method were within ±15.0% and less than 15.0%, respectively. The mean recovery and matrix effect as well as stability of all the analytes ranged from 59.27% to 90.15% and from 74.84% to 114.48% as well as within ±15.0%. This simple, rapid, and sensitive method was successfully applied in 42 sparse clinical samples to verify its practicability.

A review of the bioanalytical methods for the quantitative determination of capecitabine and its metabolites in biological matrices

“…A clear drawback of this method is that an extra step is introduced which complicates the sample pretreatment and prolongs the duration of sample pretreatment (Licea‐Perez et al, ). Wang et al () reported that they tested several separation methods (SPE and PP) and extraction fluids, but that the use of a one‐step liquid‐liquid extraction of capecitabine, 5‐‘dFCR, 5’‐dFUR, 5‐fluoro‐2’‐deoxyuridine (FdUrd), 5‐FU and 5‐FUH 2 by ethyl acetate and isopropanol (19:1, v/v) gave optimal extraction recovery (59.3% to 90.2%) (Wang et al, ).…”

“…This was shown by Wang et al . whom have tested both LLE and PP and reported that LLE could remove interfering endogenous components at the greatest extent and subsequently showed less of a matrix effect compared to PP (Wang et al, ). Nevertheless, PP can still be an excellent option for sample pre‐treatment of capecitabine and its metabolites.…”

“…For that reason 5‐CU was chosen over 5‐BU (Vainchtein et al, ). Furthermore, prescribed drugs such as fluvastatin, carbamazepine, voriconazole, gemcitabine and fludarabine have been used as IS ((Montange et al, ; Piórkowska et al, ; Siethoff et al, ; Thorat et al, ; Wang et al, ) It can be questioned if using prescribed drugs, especially commonly prescribed drugs such as fluvastatin, carbamazepine and voriconazole should be used as an IS, due to the limitation in the applicability of the assay. Depending on the use of the assay prescribed drugs can be used as an IS in for example pharamacology studies in healthy volunteers, but are not suited for clinical use such as therapeutic drug monitoring (Srinivas, ).…”

“…For that reason 5-CU was chosen over 5-BU (Vainchtein et al, 2010). Furthermore, prescribed drugs such as fluvastatin, carbamazepine, voriconazole, gemcitabine and fludarabine have been used as IS ( (Montange et al, 2010;Piórkowska et al, 2014;Siethoff et al, 2004;Thorat et al, 2018;Wang et al, 2019) It can be questioned if using prescribed drugs, especially commonly prescribed drugs such as fluvastatin, carbamazepine and voriconazole should be used as an IS, due to the limitation in the applicability of the assay.…”

“…A disadvantage of PP is that it yields less clean samples compared to SPE and LLE, which can cause matrix effect (ionization of co-eluting components in the matrix) during detection with MS. This was shown by Wang et al whom have tested both LLE and PP and reported that LLE could remove interfering endogenous components at the greatest extent and subsequently showed less of a matrix effect compared to PP(Wang et al, 2019). Nevertheless, PP can still be an excellent option for sample pre-treatment of capecitabine and its metabolites.…”