Identification and characterization of GSK-9089 metabolites through high resolution-mass spectrometry based in vitro and in vivo rat biological sample analysis

Estrogen related receptors (ERRs) agonist GSK-9089 (DY-131) reported to pose a potential in increasing exercise endurance. High resolution mass spectrometry (HRMS) based analysis has utmost importance in the detection, identification, or characterization of a molecule including its metabolites in human body. In this study, in vitro metabolism profile of GSK-9089 was investigated after incubation with liver microsomes and S9 fractions. Additionally, in vivo metabolites of the molecule were identified in plasma, urine, and faeces samples of rats. Structures of all the potential metabolites were revealed by employing an in silico tool and HRMS based analysis through data-dependent and data-independent mining strategies. Nine unknown metabolites of GSK-9089 have been identified which were found to be present in a trace amount in in vivo matrices. Most of the in vitro and in vivo phase I metabolites of the molecule were formed after imine bond hydrolysis followed by deamidation, oxidation, and N-oxidation. The molecule underwent phase II metabolism to generate more polar metabolites mainly through glucuronide, sulfate conjugation biotransformation reactions. The in vitro and in vivo metabolites of GSK-9089 could be useful to identify the abuse of this ERRs agonist in the future.

A Different Perspective on the Characterization of a New Degradation Product of Flibanserin With HPLC-DAD-ESI-IT-TOF-MSn and Its Pharmaceutical Formulation Analysis With Inter-Laboratory Comparison

BACKGROUND

Flibanserin (FLB) was first synthesized as an antidepressant drug; however, due to its enhancing effects on sexual activity, it was approved for treatment of hypoactive sexual desire disorder in women in 2015.

OBJECTIVE

The aim of this study was to develop a new and fully validated HPLC method for analysis of FLB in pharmaceutical formulations besides its degradation products, and identification of possible formation mechanisms by using HPLC-DAD-ESI-IT-TOF-MSn.

METHOD

The HPLC separation was achieved in a Supelco Ascentis® Express series phenyl hexyl column (100 × 4.6 mm, ID 2.7 µm). The mobile phase was acetonitrile-ammonium acetate solution (50:50, v/v, 10 mM, pH 5.4) mixture, which was pumped at the rate of 0.5 mL/min. Chromatography, detection, and structural identification was performed by using a LCMS-IT-TOF instrument (Shimadzu, Japan).

RESULTS

1-(2-(4-(3-hydroxy-5-(trifluoromethyl)phenyl)piperazine-1-yl)ethyl)-1,3-dihydro-2H-benzo[d]imidazol-2-one is proposed as a novel degradation product, with a mass of 407.1695 and a formula of C20H21F3N4O2 with a margin of error about 0.001 ppm. The developed method is applicable with 98% accuracy within the 2.5-50.0 µg/mL range. The LOD and LOQ were about 500 ng/mL and 1.50 µg/mL, respectively. The transferability and variation between laboratories were tested by inter-laboratory comparison and evaluated with one-way analysis of variance.

CONCLUSIONS

A novel FLB degradation product, which was produced under oxidative forced degradation conditions was observed and identified for the first time; in addition, the formation kinetics of the degradation product besides decomposition of FLB was studied. Furthermore, an inter-laboratory comparison was carried out, and application of the proposed method on a pseudo Addyi® (Sprout Pharmaceuticals, Inc.) sample was tested using both instrument configurations.

HIGHLIGHTS

A novel stability-indicating assay method was developed and fully validated according to the International Council on Harmonization (Q2) R1 for the analysis of FLB in the pharmaceutical preparations. A new degradation product was identified in the oxidative forced degradation condition and characterized using HPLC-DAD-ESI-IT-TOF-MS3. Moreover, the possible mechanism and the formation kinetic of the degradation product were revealed. In addition, the developed method was transferred to another LC-PDA instrument for inter-laboratory comparison. Finally, the current method was applied to a pseudo formulation of Addy in both instruments, and ANOVA was applied for evaluation.

LC-QQQ-MS based intracellular quantification of bictegravir in peripheral blood mononuclear cells and plasma

Most antiretrovirals (ARVs) have intracellular therapeutic target sites and therefore, their plasma concentration may be misleading when relating to their efficacy or toxicity. A bioanalytical method for quantification of the ARV drug bictegravir (BTG) in its target site peripheral blood mononuclear cells (PBMCs) is not available till date. This is the first time to establish a sufficiently sensitive mass spectrometry-based bioanalytical method to quantify BTG in both rat PBMCs and plasma. The developed method was validated over the range of 1 ng/ml to 100 ng/ml and 0.005 ng-10ng/sample for plasma and PBMCs, respectively. For PBMCs, average accuracy and precision at four quality control levels were found to be 93.30%-110.00% and 6.52%-8.25%, respectively. Plasma and intracellular pharmacokinetics of BTG was evaluated by the developed method in rats and a lack of accumulation of BTG in the PBMCs was observed. Pearson correlation coefficient data analysis indicated a moderated correlation between plasma and PBMC concentration of BTG. Therefore, it will be beneficial to include a quantification plan for BTG in its actual therapeutic target site during all its future research and development work. This reported method can be useful for site-specific monitoring of BTG in research laboratories and pharmaceutical industries.

Cutting-edge strategies and critical advancements in characterization and quantification of metabolites concerning translational metabolomics

Despite remarkable progress in drug discovery strategies, significant challenges are still remaining in translating new insights into clinical applications. Scientists are devising creative approaches to bridge the gap between scientific and translational research. Metabolomics is a unique field among other omics techniques for identifying novel metabolites and biomarkers. Fortunately, characterization and quantification of metabolites are becoming faster due to the progress in the field of orthogonal analytical techniques. This review detailed the advancement in the progress of sample preparation, and data processing techniques including data mining tools, database, and their quality control (QC). Advances in data processing tools make it easier to acquire unbiased data that includes a diverse set of metabolites. In addition, novel breakthroughs including, miniaturization as well as their integration with other devices, metabolite array technology, and crystalline sponge-based method have led to faster, more efficient, cost-effective, and holistic metabolomic analysis. The use of cutting-edge techniques to identify the human metabolite, including biomarkers has proven to be advantageous in terms of early disease identification, tracking the progression of illness, and possibility of personalized treatments. This review addressed the constraints of current metabolomics research, which are impeding the facilitation of translation of research from bench to bedside. Nevertheless, the possible way out from such constraints and future direction of translational metabolomics has been conferred.

Bioanalysis by LC-MS/MS and preclinical pharmacokinetic interaction study of ribociclib and oleanolic acid

Background: Ribociclib (RIBO), approved in 2017 for HR-positive and HER-2-negative metastatic breast cancer treatment is reported to have the potential to induce hepatobiliary toxicity in patients. Oleanolic acid (OLA) has hepatoprotective potential that can be beneficial if coadministered with RIBO. Methodology & results: The primary scope of this study was to develop quantitative bioanalytical methods for RIBO and OLA. Two methods (for +ve electrospray ionization [ESI] and -ve ESI) were developed and validated according to USFDA bioanalytical guidelines. Discussion/conclusion: A single and simple sample preparation method was developed with >75% recovery. The accuracy and precision for RIBO and OLA were within acceptable limits over the calibration range of 5-500 ng/ml. This work reports, for the first time, the drug-drug interaction potential between RIBO and OLA.

Emphasis on the incorporation of Tropaeolin OO dye and silver nanoparticles for voltammetric estimation of flibanserin in bulk form, tablets and human plasma

A novel electrochemical sensor based on the electro-deposition of silver nanoparticles (AgNPs) on Tropaeolin OO (poly-TO) layers over pencil graphite electrode (PGE) surface was fabricated for the first time for voltammetric determination of flibanserin (FBS); a drug enhances female sexual performance. Further characterization studies using cyclic voltammetry (CV), square wave voltammetry (SWV), electrochemical impedance spectroscopy (EIS) and scanning electron microscopy (SEM) were conducted. The AgNPs synergistic effect on poly-TO layers facilitates the FBS electro-oxidation in phosphate buffer solution (pH 6.0) and its determination in bulk form, tablets and in human plasma. Following ICH guidelines, validation of the proposed SWV method for FBS analysis was successfully achieved using the fabricated sensor (AgNPs@poly-TO/PGE). Under the optimal instrumental and experimental conditions, the anodic oxidation peak current was directly proportional to FBS concentration in the range from 0.1 to 8.5 μmol L^-1 with low detection and quantitation limits (0.0286 and 0.0867 μmol L^-1, respectively). High sensitivity, selectivity as well as easiness of fabrication are the main advantages of the modified sensor.

Development and validation of a novel evaporation setup-assisted TLC method with fluorescence detection for determination of flibanserin in pharmaceutical and biological samples

A specific and sensitive thin layer chromatographic method coupled with fluorescence detection for determination of flibanserin (FLN) that treats woman hypoactive sexual desire disorder was developed. The proposed method depends on the enhancement of FLN native fluorescence intensity via the exposure of the developed TLC plate to concentrated hydrochloric acid vapors. Herein, an evaporation setup needed for HCl vapors exposure step was designed for the first time to ensure a uniform distribution of the vapors throughout the developed bands on the plate. Chloroform: methanol (9.5: 0.5, v/v) was the optimum mobile phase that gave a compact band (R_f= 0.44 ± 0.02) using TLC aluminium plates precoated with silica gel G 60F₂₅₄ as a stationary phase. After exposure of the developed TLC plate to HCl vapors, the FLN bands emission intensities were measured after excitation at 275 nm. Conferring ICH guidelines, the linearity range was 20.0 - 1500.0 ng/band with a good linear relationship (r= 0.9998). Detection and quantitation limits were 5.12 and 15.50 ng/band, respectively. Also, the method was validated for accuracy, precision, robustness, specificity and selectivity. Statistical analysis verified the suitability of the proposed method for estimation of FLN in tablets and in human plasma with acceptable recoveries (98.07-101.45%).

A systematic UHPLC-Q-TOF-MS/MS based analytical approach for characterization of flibanserin metabolites and establishment of biotransformation pathway

A systematic metabolite profiling approach has paramount importance in detecting, identifying, and characterizing drug metabolites. Till date, there is no report published on the comprehensive metabolic fate of flibanserin (FLB). In this study, the structure of entire potential metabolites of FLB has been elucidated by execution of in silico tool and high resolution mass spectrometry based metabolite profiling strategy employing data-dependent and data-independent approaches. In vitro metabolism profile was investigated after incubating FLB with liver microsomes (rat and human) and S9 fractions in presence of their respective co-factors. In vivo metabolites were identified from rat plasma, urine, feces, and brain tissue samples. An efficient extraction technique was developed that made it possible to identify the metabolites generated even in extremely low concentrations. Extraction was carried out by precipitating protein and thereafter solid-phase extraction to enrich their concentration in the sample before analysis. Fourteen new metabolites have been identified and characterized. Most of the metabolites of FLB were generated due to hydrolysis and oxidation followed by glucuronide, sulfate, and methyl conjugation. Additionally, a spiking study was employed to confirm the presence of N-oxide metabolite in human liver S9 fraction and rat urine samples. Moreover, we have established the probable biotransformation pathway of FLB and successfully analyzed the toxicity potential of the metabolites using Pro Tox-II software.

Metabolite profiling of IMID-2, a novel anticancer molecule of piperazine derivative: In silico prediction, in vitro and in vivo metabolite characterization using UPLC-QTOF-MS/MS

IMID-2, a newly identified piperazine-based anticancer molecule, has been shown to be cytotoxic against various cancer cell lines. The primary aim of this research was to identify and characterize possible metabolites of the molecule formed during biotransformation. A metabolite identification study was first executed using an in silico tool to predict the possible metabolism sites of IMID-2. Thereafter, metabolites generated in vitro (rat liver microsomes, rat S9 fractions and human liver microsomes) and in vivo (rat plasma, urine and feces) were identified and characterized employing UPLC-QTOF-MS/MS. A total of eight metabolites, among which were six in phase I and two in phase II reactions, were recognized. The plausible structure of the metabolites and probable metabolic pathway have been established based on the mass fragmentation pattern, mass ppm error, ring double bond calculation and nitrogen rule. The majority of phase I metabolites were generated by N-oxidation, hydroxylation, oxidative deamination followed by reduction, oxidative dechlorination, N-dearylation, and N-dealkylation. Glucuronidation played a significant role in the formation of phase II metabolites of the molecule.

Target specific intracellular quantification of etoposide by quadrupole-time of flight based mass spectrometric method

Etoposide (ETP), a widely used chemotherapeutic agent has an intracellular target site of action. Unfortunately, the concentration of ETP in plasma does not properly reflect the concentration in its intracellular site of action. As per our knowledge, no reported bioanalytical method is available for intracellular quantification of ETP. In this research, we developed an LC-MS/MS method to quantitate ETP in intracellular compartments of MCF-7 cells. The Abcam nuclear extraction kit was used for extracting the nuclear and cytosolic protein from MCF-7 cells. The method showed excellent linearity in the 20-1000 ng/mL range. The intra and inter-day precision (%CV) including LLOQ were found to be in the range of 2.19-16.96% and 6.71-11.21%, respectively, with an accuracy of 86.87 to 110.37% and 93.03 to 100.50%, respectively. The concentration of ETP in nuclear and cytosolic fraction was successfully quantitated using the developed method. The developed method can be applied to understand the efficacy of different formulations based on the intracellular ETP concentration in vitro. It can be considered as a model method for quantification of other similar categories of drugs in their actual intracellular site of action after required optimization in the methodology.