Insight into in silico prediction and chemical degradation study of osimertinib mesylate by LC-HRMS and NMR: Investigation of a typical case of alkaline pH-mediated oxidative degradation product

Osimertinib mesylate is a third-generation epidermal growth factor receptor tyrosine kinase inhibitor used to treat nonsmall-cell lung cancer. The objective was to understand in silico prediction and chemical-based stress testing of the osimertinib mesylate. A total of eight degradation products (DPs) were formed under chemical stress testing. An in silico tool viz., Zeneth predicted a higher percentage of DPs. The separation of all the DPs was achieved using reversed phase high-performance liquid chromatography, employing X-Bridge C18 column with ammonium acetate (pH adjusted to 7.50 with ammonia) and acetonitrile as mobile phase. The overall results showed it underwent significant degradation in acidic, alkaline, and oxidative conditions. In rest of the conditions, osimertinib mesylate was found to be stable or slight degradation was observed in photolytic condition. The structure of DPs was elucidated with a comparison of data generated from high-resolution mass spectrometry (HRMS) of osimertinib mesylate and its degradation products. To confirm the unambiguous regioisomers, one-dimensional (1D) and two-dimentional (2D) nuclear magnetic resonance studies were performed. Furthermore, the N-oxide position was assigned for the first time using the Meisenheimer rearrangement reaction in atmospheric pressure chemical ionization mode. Interestingly, an unusual reaction of DP2 formation was observed at alkaline conditions. In silico tools such as DEREK and Sarah predicted osimertinib mesylate and most of the DPs found to be structural alert for mutagenicity.

In vitroand in vivo investigation of metabolic fate of riociguat by HPLC-Q-TOF/MS/MS and in silico evaluation of the metabolites by ADMET predictor™

Riociguat, a guanyl cyclase inhibitor, is one of its kind drug regimen approved for management of pulmonary arterial hypertension and chronic thromboembolism pulmonary hypertension. Extensive literature review indicates lack of comprehensive reports on its metabolic fate. The present study reports the in vivo and in vitro identification and characterization of metabolites of riociguat, using high-performance liquid chromatography-quadruple time-of-flight tandem mass spectrometry. In vitro studies were conducted by incubating the drug in human and rat liver microsomes in presence of respective cofactors. In vivo studies were undertaken by oral administration of suspension of drug to male Sprague-Dawley rats followed by collection of urine, feces and blood at specific intervals. A total of 18 metabolites were observed in in vivo and in vitro matrices which includes hydroxyl, N-oxide, desmethyl, defluorinated hydroxyl, glucuronides and N-acetyl cysteine conjugates. Presence of N-acetyl cysteine conjugates strongly points towards the formation of a reactive metabolite intermediate trapped through N-acetyl cysteine and can be considered a matter of concern as the reactive metabolites have been known to manifest toxicities. Their presence was mimicked in in vitro samples as well. The toxicological properties of drug and metabolites were evaluated by using ADMET Predictor ^™ software.

In vitro and in vivo metabolic investigation of the Palbociclib by UHPLC-Q-TOF/MS/MS and in silico toxicity studies of its metabolites

Palbociclib (PAB) is a CDK4/6 inhibitor and U. S Food and Drug Administration (FDA) granted regular approval for the treatment of hormone receptor (HR) positive, metastatic breast cancer in combination with an aromatase inhibitor in postmenopausal women. Metabolite identification is a crucial aspect during drug discovery and development as the drug metabolites may be pharmacologically active or possess toxicological activity. As there are no reports on the metabolism studies of the PAB, the present study focused on investigation of the in vitro and in vivo metabolic fate of the drug. The in vitro metabolism studies were carried out by using microsomes (HLM and RLM) and S9 fractions (Human and rat). The in vivo metabolism of the drug was studied by administration of the PAB orally to the Sprague-Dawley rats followed by analysis of urine, faeces and plasma samples. The sample preparation includes simple protein precipitation (PP) followed by solid phase extraction (SPE). The extracted samples were analyzed by ultrahigh-performance liquid chromatography-quadruple time-of-flight tandem mass spectrometry (UHPLC/Q-TOF/MS/MS). A total of 14 metabolites were detected in in vivo matrices. The PAB was metabolized via hydroxylation, oxidation, sulphation, N-dealkylation, acetylation and carbonylation pathways. A few of the metabolites were also detected in in vitro samples. Metabolite identification and characterization were performed by using UHPLC/Q-TOF/MS/MS in combination with HRMS data. To identify the toxicity potential of these metabolites, in silico toxicity assessment was carried out using TOPKAT and DEREK softwares.

Development of a stability-indicating UPLC method for terconazole and characterization of the acidic and oxidative degradation products by UPLC-Q-TOF/MS/MS and NMR

Terconazole, a triazole antifungal drug, is used to treat infections in the form of a cream or suppositories.

Identification and characterization of vilazodone metabolites in rats and microsomes by ultrahigh-performance liquid chromatography/quadrupole time-of-flight tandem mass spectrometry

RATIONALE

Vilazodone is a selective serotonin reuptake inhibitor (SSRI) used for the treatment of major depressive disorder (MDD). An extensive literature search found few reports on the in vivo and in vitro metabolism of vilazodone. Therefore, we report a comprehensive in vivo and in vitro metabolic identification and structural characterization of vilazodone using ultrahigh-performance liquid chromatography/quadrupole time-of-flight tandem mass spectrometry (UPLC/Q-TOF/MS/MS) and in silico toxicity study of the metabolites.

METHODS

To identify in vivo metabolites of vilazodone, blood, urine and faeces samples were collected at different time intervals starting from 0 h to 48 h after oral administration of vilazodone to Sprague-Dawley rats. The in vitro metabolism study was conducted with human liver microsomes (HLM) and rat liver microsomes (RLM). The samples were prepared using an optimized sample preparation approach involving protein precipitation followed by solid-phase extraction. The metabolites have been identified and characterized by using LC/ESI-MS/MS.

RESULTS

A total of 12 metabolites (M1-M12) were identified in in vivo and in vitro matrices and characterized by LC/ESI-MS/MS. The majority of the metabolites were observed in urine, while a few metabolites were present in faeces and plasma. Two metabolites were observed in the in vitro study. A semi-quantitative study based on percentage counts shows that metabolites M11, M6 and M8 were observed in higher amounts in urine, faeces and plasma, respectively.

CONCLUSIONS

The structures of all the 12 metabolites were elucidated by using LC/ESI-MS/MS. The study suggests that vilazodone was metabolized via hydroxylation, dihydroxylation, glucuronidation, oxidative deamination, dealkylation, dehydrogenation and dioxidation. All the metabolites were screened for toxicity using an in silico tool.

Identification and characterization of fluvastatin metabolites in rats by UHPLC/Q-TOF/MS/MS and in silico toxicological screening of the metabolites

The present study reports the in vivo and in vitro identification and characterization of metabolites of fluvastatin, the 3-hydroxy-3-methyl-glutaryl-coenzyme A reductase inhibitor, using liquid chromatography-mass spectrometry (LC-MS). In vitro studies were conducted by incubating the drug with human liver microsomes and rat liver microsomes. In vivo studies were carried out by administration of the drug in the form of suspension to the Sprague-Dawley rats followed by collection of urine, faeces and blood at different time points up to 24 h. Further, samples were prepared by optimized sample preparation method, which includes freeze liquid extraction, protein precipitation and solid phase extraction. The extracted and concentrated samples were analysed using ultrahigh-performance liquid chromatography-quadruple time-of-flight tandem mass spectrometry. A total of 15 metabolites were observed in urine, which includes hydroxyl, sulphated, desisopropyl, dehydrogenated, dehydroxylated and glucuronide metabolites. A few of the metabolites were also present in faeces and plasma samples. In in vitro studies, a few metabolites were observed that were also present in in vivo samples. All the metabolites were characterized using ultrahigh-performance liquid chromatography-quadruple time-of-flight tandem mass spectrometry in combination with accurate mass measurement. Finally, in silico toxicity studies indicated that some of the metabolites show or possess carcinogenicity and skin sensitization. Several metabolites that were identified in rats are proposed to have toxicological significance on the basis of in silico evaluation. However, these metabolites are of no human relevance. Copyright © 2017 John Wiley & Sons, Ltd.