Direct and fast capillary zone electrophoretic method for the determination of Gleevec and its main metabolite in human urine

Physiologically based pharmacokinetic modeling of imatinib and N-desmethyl imatinib for drug-drug interaction predictions

The first-generation tyrosine kinase inhibitor imatinib has revolutionized the development of targeted cancer therapy and remains among the frontline treatments, for example, against chronic myeloid leukemia. As a substrate of cytochrome P450 (CYP) 2C8, CYP3A4, and various transporters, imatinib is highly susceptible to drug-drug interactions (DDIs) when co-administered with corresponding perpetrator drugs. Additionally, imatinib and its main metabolite N-desmethyl imatinib (NDMI) act as inhibitors of CYP2C8, CYP2D6, and CYP3A4 affecting their own metabolism as well as the exposure of co-medications. This work presents the development of a parent-metabolite whole-body physiologically based pharmacokinetic (PBPK) model for imatinib and NDMI used for the investigation and prediction of different DDI scenarios centered around imatinib as both a victim and perpetrator drug. Model development was performed in PK-Sim® using a total of 60 plasma concentration-time profiles of imatinib and NDMI in healthy subjects and cancer patients. Metabolism of both compounds was integrated via CYP2C8 and CYP3A4, with imatinib additionally transported via P-glycoprotein. The subsequently developed DDI network demonstrated good predictive performance. DDIs involving imatinib and NDMI were simulated with perpetrator drugs rifampicin, ketoconazole, and gemfibrozil as well as victim drugs simvastatin and metoprolol. Overall, 12/12 predicted DDI area under the curve determined between first and last plasma concentration measurements (AUClast) ratios and 12/12 predicted DDI maximum plasma concentration (Cmax) ratios were within twofold of the respective observed ratios. Potential applications of the final model include model-informed drug development or the support of model-informed precision dosing.

Sensitivity enhancement of a Cu (II) metal organic framework-acetylene black-based electrochemical sensor for ultrasensitive detection of imatinib in clinical samples

Imatinib (IMB), an anticancer drug, is extensively used for chemotherapy to improve the quality of life of cancer patients. The aim of therapeutic drug monitoring (TDM) is to guide and evaluate the medicinal therapy, and then optimize the clinical effect of individual dosing regimens. In this work, a highly sensitive and selective electrochemical sensor based on glassy carbon electrode (GCE) modified with acetylene black (AB) and a Cu (II) metal organic framework (CuMOF) was developed to measure the concentration of IMB. CuMOF with preferable adsorbability and AB with excellent electrical conductivity functioned cooperatively to enhance the analytical determination of IMB. The modified electrodes were characterized using X-rays diffraction (XRD), X-ray photoelectron spectroscopy (XPS), fourier transform infrared (FT-IR), ultraviolet and visible spectrophotometry (UV-vis), electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), brunauer‒emmett‒teller (BET) and barrett‒joyner‒halenda (BJH) techniques. Analytical parameters such as the ratio of CuMOF to AB, dropping volumes, pH, scanning rate and accumulation time were investigated through cyclic voltammetry (CV). Under optimal conditions, the sensor exhibited an excellent electrocatalytic response for IMB detection, and two linear detection ranges were obatined of 2.5 nM-1.0 μM and 1.0-6.0 μM with a detection limit (DL) of 1.7 nM (S/N = 3). Finally, the good electroanalytical ability of CuMOF-AB/GCE sensor facilitated the successful determination of IMB in human serum samples. Due to its acceptable selectivity, repeatability and long-term stability, this sensor shows promising application prospects in the detection of IMB in clinical samples.

Turn-off fluorescence of nitrogen and sulfur carbon quantum dots as effective fluorescent probes for determination of imatinib. Application to biological fluids

Nitrogen and sulfur carbon quantum dots(N,S-CQDs) as effective fluorescent nanoprobes were synthesized through one-step-hydrothermal method using thiosemicarbazide (as nitrogen and sulfur source) and citric acid (as carbon source). The highly fluorescent N,S-CQDs were subjected to various characterization techniques. The fluorescence of the synthesized N,S-CQDs is characterized by maximum fluorescence emission at 415 nm after excitation at 345 nm and a high quantum yield of 0.58. The native N,S-CQDs fluorescence is quantitatively quenched upon addition of imatinib (IMA), so they are used for its spectrofluorimetric determination in its pharmaceutical formulations and biological fluids. Under optimal conditions, N,S-CQDs exhibited a "turn-off" fluorescence response to IMA over the range of 1.0 to 15.0 µg/mL with a limit of quantification of 0.42 µg/mL and a lower detection limit of 0.14 µg/mL. Stern-Volmer equation was used to study the mechanism of quenching and it was found to occur through static quenching mechanism. The method was extended to the in-vitro determination of the drug in spiked human urine and plasma samples and the percent recoveries were satisfactory.

Quantification of imatinib and related compounds using capillary electrophoresis-tandem mass spectrometry with field-amplified sample stacking

A quantification method for imatinib (IM), its major metabolite N-desmethyl imatinib (NDI), and a degradation by-product was developed using CE-MS combined with an online concentration technique. The use of multiple reaction monitoring (MRM)-MS/MS further improved the sensitivity of this technology. Liquid-liquid extraction (LLE) using tertiary butyl methyl ether yielded high recovery and reproducibility for the pretreatment of serum samples. The recovery rate exceeded 83% for all three analytes, and was 90% for IM. To improve quantification results, a conductivity-induced online analyte concentration technique, field-amplified sample stacking (FASS), was used. The S/N ratios were improved at least 10-fold when compared with conventional capillary zone electrophoresis. The detection limits were 0.2 ng/mL for IM, 0.4 ng/mL for NDI, and 4 ng/mL for the degradation by-product. These results are superior to those previously obtained by other reported methods. The new method was validated in terms of its selectivity, intra- and interday repeatability and accuracy, and sample storage stability, following the guidelines issued by the European Medicines Agency. Considering the convenient pretreatment procedure (LLE), superior sensitivity, and fast analysis speed (<15 min), this method can be useful in the determination of imatinib levels in blood.

Imatinib mesylate

Imatinib (INN), marketed by Novartis as Gleevec (United States) or Glivec (Europe/Australia/Latin America), received Food & Drug Administration (FDA) approval in May 2001 and is a tyrosine kinase inhibitor used in the treatment of multiple cancers, most notably Philadelphia chromosome-positive (Ph+) chronic myelogenous leukemia. Like all tyrosine kinase inhibitors, imatinib works by preventing a tyrosine kinase enzyme. Because the BCR-Abl tyrosine kinase enzyme exists only in cancer cells and not in healthy cells, imatinib works as a form of targeted therapy-only cancer cells are killed through the drug's action. In this regard, imatinib was one of the first cancer therapies to show the potential for such targeted action and is often cited as a paradigm for research in cancer therapeutics. This study presents a comprehensive profile of imatinib, including detailed nomenclature, formulae, physico-chemical properties, methods of preparation, and methods of analysis (including compendial, electrochemical, spectroscopic, and chromatographic methods of analysis). Spectroscopic and spectrometric analyses include UV/vis spectroscopy, vibrational spectroscopy, nuclear magnetic resonance spectrometry ((1)H and (13)C NMR), and mass spectrometry. Chromatographic methods of analyses include electrophoresis, thin layer chromatography, and high-performance liquid chromatography. Preliminary stability investigations for imatinib have established the main degradation pathways, for example, oxidation to N-oxide under oxidative stress conditions. Stability was also carried out for the formulation by exposing to different temperatures 0°C, ambient temperature, and 40°C. No remarkable change was found in the drug content of formulation. This indicates that the drug was stable at the above optimized formulation. Stability studies under acidic and alkaline conditions have established the following main degradation products: α-(4-Methyl-1-piperazinyl)-3'-{[4-(3-pyridyl)-2-pyrimidinyl] amino}-p-tolu-p-toluid-ide methanesulfonate and 4-(4-methylpiperazin-1-ylmethyl)-benzoic acid. The main degradation products under oxidation conditions, that is, 4-[(4-methyl-4-oxido-piperazin-1-yl)-methyl]-N-[4-methyl-3-(4-pyridin-3-yl-pyrimidin-2-ylamino)-phenyl]-enzamide, 4-[(4-methyl-1-oxido-piperazin-1-yl)-methyl]-N-[4-methyl-3-(4-pyridin-3-yl-pyrimidin-2-ylamino)-phenyl]-benzamide, and 4-[(4-methyl-1,4-dioxido-piperazin-1-yl)-methyl]-N-[4-methyl-3-(4-pyridin-3-yl-pyrimidin-2-ylamino)-phenyl]-enzamide. Clinical application studies for pharmacodynamics, pharmacokinetics, mechanism of action, and clinical uses of the drug were also presented. Each of the above stages includes appropriate figures and tables. More than 50 references were given as proof of the above-mentioned studies.

Nonaqueous capillary electrophoresis method for the analysis of gleevec and its main metabolite in human urine

The viability of nonaqueous capillary electrophoresis (NACE) was investigated for determination of gleevec and its main metabolite in human urine using a fused-silica capillary. Baseline separation of the studied solutes was obtained using a nonaqueous solution composed of 12 mM ammonium acetate and 87.6 mM acetic acid in methanol-acetonitrile (ACN) (80:20, v:v) providing analysis time shorter than 3 min. Different aspects including stability of the solutions, linearity, accuracy and precision were studied in order to validate the method in the urine matrix. Detection limits of 24 microg L(-1) for gleevec and its metabolite were obtained. A robustness test of the method was carried out using the Plackett-Burman fractional factorial model with a matrix of 15 experiments. The developed method is simple, rapid and sensitive and has been used to determine gleveec and its metabolite at clinically relevant levels in human urine. Before NACE determination, a solid-phase extraction (SPE) procedure with a C18 cartridge was necessary. Real determination of these analytes in two patient urines were done.

Acid−Base Profiling of Imatinib (Gleevec) and Its Fragments

The site-specific basicities of imatinib (Gleevec, a new signal transduction inhibitor drug of chronic myeloid leukemia) and two of its fragment compounds were quantitated in terms of protonation macroconstants, microconstants, and group constants by NMR-pH and pH-potentiometric titrations. Sequential protonation of imatinib follows the N(34), N(11), N(31), N(13) order, in which N(11) and N(31) show commensurable basicity, but negligible intramolecular interaction. Fragment compounds include two "halves" of imatinib, and their moiety-specific basicities confirm the NMR-based protonation sequence of the parent compound. NMR-pH profiles, macro- and/or microscopic protonation schemes, and species-specific distribution diagrams are presented. On the basis of these data, imatinib is shown to be predominantly neutral, monocationic, and tricationic at intestinal, blood, and gastric pH, respectively. The molecular hypotheses on imatinib binding to the Bcr-Abl oncogene fusion protein are interpreted at the site-specific level in view of the moiety basicities of imatinib.

Voltammetric behavior and quantification of the anti-leukemia drug imatinib in bulk form, pharmaceutical formulation, and human serum at a mercury electrode

Imatinib (GleevecTM, ST1571) exemplifies the successful development of a rationally designed molecularly targeted therapy for treatment of a specific cancer. It is a highly promising new drug for the treatment of chronic myelogenous leukemia in blast crisis, in the accelerated or chronic phase after interferon failure or intolerance. The electrochemical behavior of imatinib was studied in Britton–Robinson (B–R) buffers of pH 2 to 11 by means of cyclic voltammetry at a hanging mercury drop electrode. The voltammograms showed a single 2-electron irreversible cathodic peak, which may be attributed to reduction of the C=O double bond of the imatinib molecule. Imatinib exhibited a strong adsorption onto the electrode surface especially in B–R buffers of pH 6 and 7. The adsorptive response of the drug was optimized with respect to the pH of the electrolysis medium, accumulation variables, and instrumental parameters using a square-wave stripping voltammetry technique. A fully validated, simple, sensitive, precise, and selective square-wave adsorptive cathodic stripping voltammetric procedure is described for trace determination of imatinib. The limits of detection (LOD) and quantitation (LOQ) of the bulk imatinib, following preconcentration for 150 s onto the hanging mercury drop electrode, were found to be 2.6 × 10–10 and 8.7 × 10–10 mol/L, respectively. The proposed procedure was successfully applied for quantitation of imatinib in pharmaceutical formulation (Glivec®) and spiked human serum, without the necessity for sample pretreatment or time-consuming extraction or evaporation steps prior to analysis of the drug. LOD and LOQ of 4.6 × 10–10 and 1.5 × 10–9 mol/L, respectively, were achieved after 120 s of preconcentration of the drug spiked in human serum.Key words: imatinib, GleevecTM, Glivec®, ST1571, cyclic voltammetry, square-wave stripping voltammetry, electrochemical behavior, quantification, pharmaceutical formulation, human serum.