Comparison of electrospray ionisation, atmospheric pressure chemical ionisation and atmospheric pressure photoionisation for the identification of metabolites from labile artemisinin-based anti-malarial drugs using a QTRAP® mass spectrometer

What is the role of current mass spectrometry in pharmaceutical analysis?

The role of mass spectrometry (MS) has become more important in most application domains in recent years. Pharmaceutical analysis is specific due to its stringent regulation procedures, the need for good laboratory/manufacturing practices, and a large number of routine quality control analyses to be carried out. The role of MS is, therefore, very different throughout the whole drug development cycle. While it dominates within the drug discovery and development phase, in routine quality control, the role of MS is minor and indispensable only for selected applications. Moreover, its role is very different in the case of analysis of small molecule pharmaceuticals and biopharmaceuticals. Our review explains the role of current MS in the analysis of both small-molecule chemical drugs and biopharmaceuticals. Important features of MS-based technologies being implemented, method requirements, and related challenges are discussed. The differences in analytical procedures for small molecule pharmaceuticals and biopharmaceuticals are pointed out. While a single method or a small set of methods is usually sufficient for quality control in the case of small molecule pharmaceuticals and MS is often not indispensable, a large panel of methods including extensive use of MS must be used for quality control of biopharmaceuticals. Finally, expected development and future trends are outlined.

A Microbial Transformation Model for Simulating Mammal Metabolism of Artemisinin

Artemisinin (ART) is a highly effective antimalarial agent isolated from the traditional Chinese herb Qinghao. Metabolism of ART and its derivatives in the body is one of the most pressing issues for pharmaceutical scientists. Herein, an efficient in vitro microorganism model for simulation of metabolism of ART in vivo was developed employing Cunninghamella elegans. Metabolites in the microbial transformation system and plasma of mice pre-administrated ART orally were analyzed by ultra-performance liquid chromatography (UPLC)-electrospray ionization (ESI)-quadrupole time-of-flight (Q-TOF)-mass spectrometry (MS^E) combined with UNIFI software. Thirty-two metabolites were identified in vitro and 23 were identified in vivo. After comparison, 16 products were found to be common to both models including monohydroxylated ART, dihydroxylated ART, deoxyartemisinin, hydroxylated deoxyartemisinin, hydroxylated dihydroartemisinin (DHA), and hydroxylated deoxy-DHA. These results revealed that C. elegans CICC 40250 functioned as an appropriate model to mimic ART metabolism in vivo. Moreover, an overall description of metabolites of ART from C. elegans CICC 40250 has been provided. Notably, DHA was detected and identified as a metabolite of ART in mouse plasma for the first time.

Determination of artemisitene in rat plasma by ultra-performance liquid chromatography/tandem mass spectrometry and its application in pharmacokinetics

RATIONALE

Artemisitene shows a wide variety of pharmacological activities, such as antioxidant protection in vitro and in vivo. It has been identified as a novel Nrf2 inducer. However, there is no report on an ultra-performance liquid chromatography/tandem mass spectrometry (UPLC/MS/MS) method to quantitate artemisitene in rat plasma and its application to a pharmacokinetic profile study.

METHODS

An ACQUITY UPLC™ BEH Symmetry Shield RP18 column (1.7 μm, 2.1 mm × 100 mm) was used at a flow rate of 0.3 mL·min^-1 . Mass detection was performed by electrospray ionization tandem mass spectrometry via multiple reaction monitoring (MRM) in positive mode. Plasma samples were pre-treated by a single-step extraction with 0.1% formic acid aqueous solutions-acetonitrile, and tolbutamide was used as internal standard.

RESULTS

The calibration curve was from 0.98 to 1000 ng∙mL^-1 (r²  = 0.995). The extraction recoveries were 61.5-79.4% and 81.7-94.6% for artemisitene and tolbutamide, respectively. The lower limit of quantification (LLOQ) was 0.98 ng∙mL^-1 . The absolute bioavailability of artemisitene was 3.7% after intravenous and oral administration in rats.

CONCLUSIONS

The UPLC/MS/MS assay was validated for linearity, accuracy, stability, extraction recovery, matrix effects, and intra-day and inter-day precision. The method, for the first time, achieved some pharmacokinetic parameters and was successfully applied to a pharmacokinetic study Copyright © 2017 John Wiley & Sons, Ltd.

Multiple stage MS in analysis of plasma, serum, urine and in vitro samples relevant to clinical and forensic toxicology

This paper reviews MS approaches applied to metabolism studies, structure elucidation and qualitative or quantitative screening of drugs (of abuse) and/or their metabolites. Applications in clinical and forensic toxicology were included using blood plasma or serum, urine, in vitro samples, liquids, solids or plant material. Techniques covered are liquid chromatography coupled to low-resolution and high-resolution multiple stage mass analyzers. Only PubMed listed studies published in English between January 2008 and January 2015 were considered. Approaches are discussed focusing on sample preparation and mass spectral settings. Comments on advantages and limitations of these techniques complete the review.

A Functional Group Approach for Prediction of APPI Response of Organic Synthetic Targets

Atmospheric pressure photoionization (APPI) is a technique of choice for ionization of non-polar molecules in mass spectrometry (MS). Reported APPI-based studies tend to focus on a selected compound class, which may contain a variety of functional groups. These studies demonstrate that APPI response frequently differs substantially, indicating a certain dependence on the functional group present. Although this dependence could be employed for APPI response prediction, its systematic use is currently absent. Here, we apply APPI MS to a judiciously-compiled set of 63 compounds containing a number of diverse functional groups commonly utilized in synthesis, reactive functional groups, as well as those containing boron and silicon. Based on the outcome of APPI MS of these compounds, we propose and evaluate a simple guideline to estimate the APPI response for a novel compound, the key properties of which have not been characterized in the gas phase. Briefly, we first identify key functional groups in the compound and gather knowledge on the known ionization energies from the smallest analogues containing said functional groups. We then consider local inductive and resonance effects on said ionization energies for the compounds of interest to estimate the APPI response. Finally, application of APPI MS to compounds of interest considered herein demonstrated extended upper mass ionization limit of 3.5 kDa for non-polymeric compounds.

Stepwise optimization approach for improving LC-MS/MS analysis of zwitterionic antiepileptic drugs with implementation of experimental design

In this article, a step-by-step optimization procedure for improving analyte response with implementation of experimental design is described. Zwitterionic antiepileptics, namely vigabatrin, pregabalin and gabapentin, were chosen as model compounds to undergo chloroformate-mediated derivatization followed by liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) analysis. Application of a planned stepwise optimization procedure allowed responses of analytes, expressed as areas and signal-to-noise ratios, to be improved, enabling achievement of lower limit of detection values. Results from the current study demonstrate that optimization of parameters such as scan time, geometry of ion source, sheath and auxiliary gas pressure, capillary temperature, collision pressure and mobile phase composition can have a positive impact on sensitivity of LC-MS/MS methods. Optimization of LC and MS parameters led to a total increment of 53.9%, 83.3% and 95.7% in areas of derivatized vigabatrin, pregabalin and gabapentin, respectively, while for signal-to-noise values, an improvement of 140.0%, 93.6% and 124.0% was achieved, compared to autotune settings. After defining the final optimal conditions, a time-segmented method was validated for the determination of mentioned drugs in plasma. The method proved to be accurate and precise with excellent linearity for the tested concentration range (40.0 ng ml(-1)-10.0 × 10(3)  ng ml(-1)).

Surface-activated chemical ionization-electrospray ionization mass spectrometry combined with two-dimensional serial chromatography is a powerful tool for drug stability studies

RATIONALE

Drug stability is an important quality-control issue for pharmaceutical and clinical practices. Among the analytical techniques that address this issue, liquid chromatography/mass spectrometry (LC/MS) can be very useful, especially when assessing the quality of liquid formulations, because it is intrinsically sensitive, selective, and a rapid analytical technique. However, LC/MS suffers from technical drawbacks, e.g., matrix effects, and the production of in-source degradation products, which can limit its usefulness.

METHODS

To overcome the aforementioned drawbacks associated with LC/MS, we introduce an innovative approach (2D-LC/SACI-ESI-MS/MS) that incorporates two-dimensional liquid chromatography (2D-LC) in conjunction with an MS system consisting of a surface-activated chemical ionization-electrospray ionization chamber (SACI-ESI), an ion trap MS analyzer, and tandem mass spectrometry.

RESULTS

To validate our 2D-LC/SACI-ESI-MS/MS system stability studies were performed on the computerized tomography contrast agents, iohexol, iodixanol, iopamidol, iomeprol, iopromide, and iobitridol, either alone or in binary combination. The matrix effects, in-source analyte degradation, and analytical performance were compared with those obtained using a one-dimensional LC/MS configuration. The accuracy coefficient of variance (CV) = 1-4%, and degradation (loss of water and other chemical moieties) was greatly reduced, attesting to the usefulness of this system for drug stability measurements.

CONCLUSIONS

Our new approach improves the performance (sensitivity, accuracy, and signal stability) of LC/MS instrumentation for drug stability measurements by reducing signal suppression effects and in-source chemical reactions.