High-resolution AP-SMALDI MSI as a tool for drug imaging in Schistosoma mansoni.

Schistosoma mansoni is a parasitic flatworm causing schistosomiasis, an infectious disease affecting several hundred million people worldwide. Schistosomes live dioeciously, and upon pairing with the male, the female starts massive egg production, which causes pathology. Praziquantel (PZQ) is the only drug used, but it has an inherent risk of resistance development. Therefore, alternatives are needed. In the context of drug repurposing, the cancer drug imatinib was tested, showing high efficacy against S. mansoni in vitro. Besides the gonads, imatinib mainly affected the integrity of the intestine in males and females. In this study, we investigated the potential uptake and distribution of imatinib in adult schistosomes including its distribution kinetics. To this end, we applied for the first time atmospheric-pressure scanning microprobe matrix-assisted laser desorption/ionization mass spectrometry imaging (AP-SMALDI MSI) for drug imaging in paired S. mansoni. Our results indicate that imatinib was present in the esophagus and intestine of the male as early as 20 min after in vitro exposure, suggesting an oral uptake route. After one hour, the drug was also found inside the paired female. The detection of the main metabolite, N-desmethyl imatinib, indicated metabolization of the drug. Additionally, a marker signal for the female ovary was successfully applied to facilitate further conclusions regarding organ tropism of imatinib. Our results demonstrate that AP-SMALDI MSI is a useful method to study the uptake, tissue distribution, and metabolization of imatinib in S. mansoni. The results suggest using AP-SMALDI MSI also for investigating other antiparasitic compounds and their metabolites in schistosomes and other parasites.

Method development for determination of imatinib and its major metabolite, N-desmethyl imatinib, in biological and environmental samples by SA-SHS-LPME and HPLC.

A salting-out-assisted switchable hydrophilicity solvent-based liquid phase microextraction (SA-SHS-LPME) was developed for the separation and determination of trace amounts of imatinib and N-desmethyl imatinib in biological and environmental samples by HPLC-UV. Triethylamine as a hydrophobic compound and protonated triethylamine carbonate as a hydrophilic one were switched by the addition or elimination of CO2 . The use of NaOH resulted in the elimination of CO2 from the sample solution, which led to the conversion of P-TEA-C into triethylamine (TEA) and as a result, the analytes was extracted and entered the TEA phase. The salting out was performed to speed up the formation of the TEA in the shape of fine droplets in the specimen solution. Furthermore, the impact of several momentous factors that influence the recovery of the extraction was investigated. Under the optimum conditions, the limit of detection and limit of quantification were obtained in ranges of 0.03-0.05 and 0.1-0.15 µg L-1 for imatinib and 0.04-0.06 and 0.13-0.20 µg L-1 for N-desmethyl imatinib, respectively. The preconcentration factor was 250. Inter- and intraday precision (RSD, n = 5) was <5%. In the case of imatinib and N-desmethyl imatinib in biological and environmental specimens, a range of 97.0-102% was obtained as the recovery.

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.

Characterization of imatinib mesylate formulations distributed in South American countries: Determination of genotoxic impurities by UHPLC-MS/MS and dissolution profile.

Imatinib mesylate (IM) is an anti-neoplasic drug used for the treatment of cancer. Recent new guidelines specify daily doses and concentration limits for genotoxic impurities (GTIs) in pharmaceutical final products. Therefore, in this work an analytical method using UHPLC-MS/MS was developed, validated and applied to characterize IM tablets for two GTIs: N-(2-methyl-5-aminophenyl)-4-(3-pyridyl)-2-pyrimidine amine (Imp. 1), and N-[4-methyl-3-(4-methyl-3-yl-pyrimidin-2-ylamino)-phenyl]-4- chloromethyl benzamide (Imp. 2), simultaneously. Additionally, dissolution data of IM tablets were compared using a methodology recommended by the US Food and Drug Administration. The UHPLC method utilized an Acquity BEH C18 (150 × 2.1 mm, 1.7 µm) maintained at 40°C. The mobile phase consisted of ammonium formate 0.063% (phase A) and acetonitrile plus 0.05% formic acid (phase B) in gradient elution. A sensitive method for determination of previously mentioned GTIs in IM tablets was successfully developed and applied. Overall, the formulations analyzed in this work showed low levels of Imp. 1 and Imp. 2. However, the sample named D1 showed very high levels of Imp. 1 and failed to meet the requirements established by the US Food and Drug Administration for dissolution data. Periodic verification of GTIs in pharmaceutical formulations is important to minimize safety risks, so analytical methods to determine it need be available and implemented in routine analysis.

A novel spectrofluorimetric method for determination of imatinib in pure, pharmaceutical preparation, human plasma, and human urine.

The following paper represents a simple, highly sensitive, responsive validated and developed spectrofluorimetric method for estimation of imatinib (IMB) in its pure, commercial preparation, human urine and human blood plasma. The calibration curve was in the range 4-900 ng ml-1 for pure form and urine and 8-900 ng ml-1 for plasma in a medium contains carboxymethyl cellulose (CMC) and acetate buffer (pH 5) with excitation wavelength (λex ) 230 nm and emission wavelength (λem ) 307 nm. The limit of detection (LOD) was 0.37 ng ml-1 for the pure form, 0.64 ng ml-1 for human urine, and 0.70 ng ml-1 for human plasma, while the limit of quantitation (LOQ) was 1.2 for pure form, 1.91 for urine and 2.1 for plasma. The suggested method was successfully applied for evaluation of IMB in tablets within 99% mean percentage recovery. The excipients that are usually used as additives in pharmaceutical dosage form did not interfere with the suggested method. The method was efficiently used for estimation of IMB in human urine and human plasma. The effect of some cations that might be present in urine and plasma was also studied. The method was also focused on human volunteers and in vitro drug release.

Detecting Low-Abundance Molecules at Single-Cell Level by Repeated Ion Accumulation in Ion Trap Mass Spectrometer.

Low-abundance metabolites or proteins in single-cell samples are usually undetectable by mass spectrometry (MS) due to the limited amount of substances in single cells. This limitation inspired us to further enhance the sensitivity of commercial mass spectrometers. Herein, we developed a technique named repeated ion accumulation by ion trap MS, which is capable of enhancing the sensitivity by selectively and repeatedly accumulating ions in a linear ion trap for up to 25 cycles. The increase in MS sensitivity was positively correlated with the number of repeated cycles. When ions were repeatedly accumulated for 25 cycles, the sensitivity of adenosine triphosphate detection was increased by 22-fold within 1.8 s. Our technique could stably detect low-abundance ions, especially MSn ions, at the single-cell level, such as 5-methylcytosine hydrolyzed from sample equivalent to ∼0.2 MCF7 cell. The strategy presented in this study offers the possibility to aid single-cell analysis by enhancing MS detection sensitivity.

Determination of sulfonate ester genotoxic impurities in imatinib mesylate by gas chromatography with mass spectrometry.

Methyl methanesulfonate and ethyl methanesulfonate are potential genotoxic impurities in imatinib mesylate. In this work, a simple, sensitive, reliable, and fast gas chromatography with mass spectrometry method for the simultaneous determination of methyl methanesulfonate and ethyl methanesulfonate was developed and validated. Total analysis time was only 7 min. An n-hexane/water solution was used to dissolve samples, and then extracted-ion-chromatogram mode was used to quantify methyl methanesulfonate and ethyl methanesulfonate. Calibration curves showed good linearity over the studied range for methyl methanesulfonate and ethyl methanesulfonate. The correlation coefficient of fit exceeded 0.999 for each impurity. The LOD and LOQ of methyl methanesulfonate and ethyl methanesulfonate were as low as 0.001 and 0.005 µg/mL, respectively, with RSDs of the peak area within 1.06-1.96%. Method accuracy was within 97.2-99.8% for methyl methanesulfonate and ethyl methanesulfonate. Therefore, this method can be used to quantify methyl methanesulfonate and ethyl methanesulfonate impurities at extremely low levels in imatinib mesylate.

Pharmacokinetic interaction study of combining imatinib with dasatinib in rats by UPLC-MS/MS.

This study examined whether oral administration of dasatinib to the rats with imatinib led to any pharmacokinetic interactions. Twenty-four rats were divided randomly into three groups, imatinib group (imatinib 25 mg/kg, n = 8), dasatinib group (dasatinib 15 mg/kg, n = 8) and co-administration group (dasatinib 15 mg/kg and imatinib 25 mg/kg, n = 8). The concentration of imatinib and dasatinib in rat plasma was determined by a sensitive and simple UPLC-MS/MS method. There was statistical pharmacokinetics difference for imatinib in the imatinib group and co-administration group, when co-oral administration imatinib with dasatinib, MRT(0-t) increased (p < 0.01). There was statistical pharmacokinetics difference for dasatinib in the dasatinib group and co-administration group, when co-oral administration dasatinib with imatinib, Cmax and AUC increased (p < 0.01), CL and V decreased (p < 0.01). These data indicate dasatinib could slightly influence the pharmacokinetic profile of imatinib in rats, and imatinib could influence the pharmacokinetic profile of dasatinib in rats, which might cause drug-drug interactions when using imatinib with dasatinib.

In Situ Growth of Metal-Organic Framework HKUST-1 on Graphene Oxide Nanoribbons with High Electrochemical Sensing Performance in Imatinib Determination.

Metal-organic frameworks (MOFs) have been previously investigated as electrode materials for developing electrochemical sensors. They have usually been reported to suffer from poor conductivity and improvement in the conductivity of MOFs is still a great challenge. Here, we reported the fabrication of an electrochemical sensor based on the in situ growth of framework HKUST-1 on conductive graphene oxide nanoribbons (GONRs)-modified glassy carbon electrode (GCE) (HKUST-1/GONRs/GCE). The as-fabricated modified electrode was characterized using field emission scanning electron microscopy, transmission electron microscopy (TEM), high-resolution TEM, Fourier transform infrared, X-ray diffraction, electrochemical impedance spectroscopy, cyclic voltammetry, and Raman spectroscopy. The voltammetric response of HKUST-1/GONRs/GCE toward Imatinib (IMA), as an anticancer drug, is dramatically higher than HKUST-1/GCE because of the synergic effect of the GONRs and HKUST-1 framework. The calibration curve at the HKUST-1/GONRs/GCE for IMA covered two linear dynamic ranges, 0.04-1.0 and 1.0-80 µmol L-1, with a detection limit of 0.006 µmol L-1 (6 nmol L-1). Taking advantage of the conductivity of GONRs and large surface area of HKUST-1, a sensitive modified electrode was developed for the electrochemical determination of IMA. The present method provides an effective strategy to solve the poor conductivity of the MOFs. Finally, the obtained electrochemical performance made this modified electrode promising in the determination of IMA in urine and serum samples.

Development and validation of a sensitive method for alkyl sulfonate genotoxic impurities determination in drug substances using gas chromatography coupled to triple quadrupole mass spectrometry.

Alkyl sulfonate esters have been widely concerned as genotoxic impurities (GTIs). A gas chromatography triple-quadrupole mass spectrometry (GC-MS/MS) method has been developed for trace determination of 9 commonly encountered sulfonate esters in drug substances. Three different solvents of acetonitrile (ACN), dichloromethane (DCM) and ethyl acetate (EtOAc) were evaluated as diluents to accommodate different solubilities of test articles and multiple reactions monitoring (MRM) mode was applied for quantitation of these 9 GTIs. The method was validated in terms of linearity, sensitivity, injection precision, accuracy and solution stability. The limit of quantitation (LOQ) for the 9 commonly encountered sulfonate esters in drug substances was within 0.10-1.05 ng mL-1, which was much lower than the reported LOQs in other methods (2.5-1500 ng mL-1). It is indicated that the method gave extremely high sensitivity for all the target analytes. The correlation coefficient (r) values of 9 GTIs were no less than 0.9993 in the range of 2.0-100 ng mL-1. Recoveries of all the target analytes at 10, 20, 50 ng mL-1 (equivalent to 2, 4, 10 ppm relative to 5 mg mL-1 API samples) in two different drug substance (capecitabine and imatinib methanesulfonate) were within 75%˜120%. All alkyl sulfonates were stable in these three solvents up to 36 h. This method has been successfully used for determination of these alkyl sulfonates in capecitabine and imatinib methanesulfonate and can be further applied to other drug substances.

Evaluation of a liquid electron ionization liquid chromatography-mass spectrometry interface.

Liquid Electron Ionization (LEI), is an innovative liquid chromatography-mass spectrometry (LC-MS) interface that converts liquid HPLC eluent to the gas-phase in a mass spectrometer equipped with an electron ionization (EI) source. LEI extends the electronic spectra libraries access to liquid chromatography, providing a powerful tool in the untargeted approacssh. Negligible matrix effects allow accurate quantitative information. The purpose of this research was to evaluate the main aspects concerning the interfacing process. These fundamental studies were necessary to understand the mechanism of LEI in details, and improve the interfacing process, especially regarding robustness and sensitivity. Hardware components were installed to prevent analytes precipitation, reduce thermal decomposition of sensitive compounds, and to stabilize the nano-flow delivery with different mobile-phase compositions. Particular attention was devoted to insulating the heated vaporization area from the LC part of the system. Experiments were performed to optimize the interface inner capillary dimensions, and other operative parameters, including temperature, gas and liquid flow rates. Test compounds of environmental interest were selected based on molecular weight, thermal stability, volatility, and polarity. Robustness was evaluated with a set of replicated injections and calibration experiments using a soil matrix as a test sample. MRM detection limits in the low-picogram range were obtained for five pesticides belonging to different classes in a soil sample. High-quality electron ionization mass spectra of a mixture of pesticides were also obtained.

New spectrophotometric/chemometric assisted methods for the simultaneous determination of imatinib, gemifloxacin, nalbuphine and naproxen in pharmaceutical formulations and human urine.

In this paper, novel univariate and multivariate regression methods along with model-updating technique were developed and validated for the simultaneous determination of quaternary mixture of imatinib (IMB), gemifloxacin (GMI), nalbuphine (NLP) and naproxen (NAP). The univariate method is extended derivative ratio (EDR) which depends on measuring every drug in the quaternary mixture by using a ternary mixture of the other three drugs as divisor. Peak amplitudes were measured at 294nm, 250nm, 283nm and 239nm within linear concentration ranges of 4.0-17.0, 3.0-15.0, 4.0-80.0 and 1.0-6.0µgmL-1 for IMB, GMI, NLP and NAB, respectively. Multivariate methods adopted are partial least squares (PLS) in original and derivative mode. These models were constructed for simultaneous determination of the studied drugs in the ranges of 4.0-8.0, 3.0-11.0, 10.0-18.0 and 1.0-3.0µgmL-1 for IMB, GMI, NLP and NAB, respectively, by using eighteen mixtures as a calibration set and seven mixtures as a validation set. The root mean square error of predication (RMSEP) were 0.09 and 0.06 for IMB, 0.14 and 0.13 for GMI, 0.07 and 0.02 for NLP and 0.64 and 0.27 for NAP by PLS in original and derivative mode, respectively. Both models were successfully applied for analysis of IMB, GMI, NLP and NAP in their dosage forms. Updated PLS in derivative mode and EDR were applied for determination of the studied drugs in spiked human urine. The obtained results were statistically compared with those obtained by the reported methods giving a conclusion that there is no significant difference regarding accuracy and precision.

First report of imatinib measurement in hair: Method development and preliminary evaluation of the relation between hair and plasma concentrations with therapeutic response in chronic myeloid leukemia.

BACKGROUND: Imatinib (IM) is a first choice drug for treatment of chronic myeloid leukemia (CML), with a widely accepted concentration threshold of 1000ng/ml being used as a target for therapeutic drug monitoring. Once adherence to the pharmacotherapeutic regimen is of paramount importance during the long treatment course of CML, the measurement of hair IM concentrations could be a surrogate of the patient's exposure to the drug. METHODS: IM was extracted from a 5mg hair sample by a liquid-liquid extraction with ethyl acetate, and IM-d8 was used as internal standard (IS). After evaporation, and reconstitution in acetonitrile, the extract was injected into a LC-MS/MS system. Compounds were eluted on a C8 column in isocratic mode. IM and IS were identified in positive electrospray ionization mode using ion transitions of m/z 494.5>394.5 and 503.0>394.3 respectively. The method was applied to 102 paired hair and samples obtained from CML patients. Treatment response was evaluated according to the European LeukemiaNet recommendations. RESULTS: The assay was validated in the concentration range of 0.5-25ng/mg, with intra- and inter-assay imprecisions of <13.1% and <9.3%, respectively. The limits of quantification and detection were 0.5 and 0.15ng/mg, respectively. Median hair IM concentrations are significantly smaller in patients with therapeutic failure when compared with patients with partial or optimal response (4.63 vs. 7.93, p=0.040), the same trend presented by median plasma IM concentrations (629.5 vs. 1084.8, p=0.009). An IM hair concentration below 5.8ng/mg has 83% sensibility and 70% specificity to identify patients with therapeutic failure. CONCLUSIONS: A fast, sensitive, and selective LC-MS/MS method allowing quantification of IM in hair samples was developed and validated. CML patients with therapeutic failure had significantly lower hair IM concentrations when compared with patients with optimal response. These preliminary findings may support the use of hair as a matrix for IM monitoring in clinical settings, with significant logistic advantages over the collection of venous blood, particularly in developing countries.

Quantitative determination of two polymorphic forms of imatinib mesylate in a drug substance and tablet formulation by X-ray powder diffraction, differential scanning calorimetry and attenuated total reflectance Fourier transform infrared spectroscopy.

Imatinib has been identified as a tyrosine kinase inhibitor that selectively inhibits the Abl tyrosine kinases, including Bcr-Abl. The active substance used in drug product is the mesylate salt form of imatinib, a phenylaminopyrimidine derivative and chemically named as N-(3-(4-(pyridin-3-yl) pyrimidin-2-ylamino)-4-methylphenyl)-4-((4-methylpiperazin-1-yl) methyl)-benzamide methanesulfonic acid salt. It exhibits many polymorphic forms and most stable and commercialized polymorphs are known as α and ß forms. Molecules in α and ß polymorphic forms exhibit significant conformational differences due to their different intra- and intermolecular interactions, which stabilize their molecular conformations and affect their physicochemical properties such as bulk density, melting point, solubility, stability, and processability. The manufacturing process of a drug tablet included granulation, compression, coating, and drying may cause polymorphic conversions. Therefore, polymorphic content of the drug substance should be controlled during quality control and stability testing. Attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy, differential scanning calorimetry (DSC), and powder X-ray diffraction (PXRD) methods were evaluated for determination of the polymorphic content of the drug substance and drug product; and PXRD was the most accurate technique and selected as preferred method and validated. Prior to development of a quantification method, pure α and ß polymorphs were characterized and used throughout the method development and validation studies. Mixtures with different ratios of α and ß forms were scanned using X-ray diffractometer with a scan rate of 0.250°/min over an angular range of 19.5-21.0° 2θ and the peak heights for characteristic peak of ß form at 20.5 ± 0.2° 2θ diffraction angle were used to generate a calibration curve. The detection limit of ß polymorph in α form imatinib mesylate tablets was found as 4% and the linear regression analysis data for the calibration plots showed good linear relationship with correlation coefficient of 0.992 with respect to relative peak height in the concentration range of 12-75 wt% ß form containing tablet mixtures. The obtained results at each stage of the validation study proved that the method is specific, repeatable, precise and accurate, and could be used for determination of ß polymorph content in tablets produced by using α polymorph of imatinib mesylate. The developed PXRD quantification method was used to monitor the polymorphic purity of α form drug substance and corresponding drug products during the quality control analyses and stability studies, and the results indicated that α form was stable and not converted to ß form during the manufacturing process and stability period.

Development of analytical method for quantification of antineoplastic in drug delivery systems

Nos últimos anos têm crescido cada vez mais o número de pesquisas envolvendo nanotecnologia para obtenção de medicamentos com liberação controlada, pois esses sistemas podem: proteger o fármaco de incompatibilidades tanto biológicas quanto físico-químicas assim como controlar a biodisponibilidade do fármaco. Embora com todas essas vantagens não existem métodos in vitro realmente capazes de prever com precisão a liberação dos fármacos por esses sistemas, por esse motivo, é muito importante o desenvolvimento de métodos de liberação in vitro para determinar a cinética de liberação desses sistemas.O presente trabalho teve como objetivo desenvolver e validar os métodos de eletroforese capilar (CE) e cromatografia líquida de alta eficiência (HPLC) para determinar a eficiência de encapsulação do fármaco imatinibe em nanopartículaspreviamente elaboradas e caracterizadas, assim como estudar sua liberação in vitro por CE. As nanopartículas foramdesenvolvidas pelo método de nanoprecipitaçãoe caracterizadas quanto ao tamanho, potencial zeta, morfologia e eficiência de encapsulação. A eletroforese capilar é uma técnica alternativa muito promissora em relação ao HPLC devido ao seu baixo custo, menor tempo de corrida e menos poluente ao meio ambiente. Os métodos de quantificação por CE e HPLCforam desenvolvidose validadossegundo as diretrizes do ICH, Farmacopeia Americana e ANVISA, permitindo desenvolver um estudo de liberação.As nanoesferas desenvolvidas apresentaram diâmetro médio próximo a 150nm, com índice de polidispersão menor que 0,1 e aproximadamente 90% de eficiência de encapsulação. Ambos métodos se mostraram lineares com coeficientes de determinação superiores a 0,99, os métodos se mostraram precisos (%DPR< 2), exatos(101,0±4,2% e 98,0±2,5% para HPLC e CE, respectivamente)e seletivos.O método de CE permitiu desenvolver um método de estudo de liberação independente das membranas de diálise

In recent years, there has been a growing number of researches involving nanotechnology to obtain controlled release drugs, these systems can: protect the drug against biological and physico-chemical incompatibilities; controlling the bioavailability of the drug. Although with all these advantages there are no in vitro methods really capable of accurately predicting drugs release by such systems, therefore, the development of in vitro release methods to determine the release kinetics of such systems is very important. The objective of the present work was to develop and validate capillary electrophoresis (CE) and HPLC methods to determine the encapsulation efficiency of the imatinib drug in previously elaborated and characterized nanoparticles, as well as to study its release in vitro by CE method. The nanoparticles were synthesized using the nanoprecipitation method and characterized by size, zeta potential, morphology and encapsulation efficiency. Capillary electrophoresis is a very promising alternative to HPLC because of its low cost, less runtime and less polluting environment. The CE and HPLC methodswere developed and validated according ICH, American Pharmacopoeia and ANVISA guidelines.Developed nanospheres had an average diameter close to 150nm, with polydispersity index less than 0.1 and approximately 90% encapsulation efficiency. Both methods were linear with determination coefficients higher than 0.99, the methods were precise (%RSD < 2), accurate (101.0±4,2% and 98.0±2,5% for HPLC and CE, respectively) and selective. Capillary electrophoresis method allowed to develop a drug release study independent of dialysis membranes