New Perspectives on Acyl Glucuronide Risk Assessment in Drug Discovery: Investigation of In vitro Stability, In situ Reactivity, and Bioactivation

Gunduz, Mithat; Argikar, Upendra A.; Cirello, Amanda; Dumouchel, Jennifer L.

doi:10.2174/1872312812666180611113656

Cited by 13 publications

(16 citation statements)

References 49 publications

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“…Hence, there is no isomerization into Δ-8 isomer during in vitro metabolism. This interpretation is in line with Hanisch et al [28] who concluded that this peaks does not represent Δ-8-THC-COOH but an artifact, which may arise from acyl migration of the corresponding phase II metabolite THC-COOH glucuronide [29].…”

Section: Investigation Of Inseparable (−)-11-oh-δ-9-thc-glc and G3supporting

confidence: 88%

Investigation of phase II metabolism of 11-hydroxy-Δ-9-tetrahydrocannabinol and metabolite verification by chemical synthesis of 11-hydroxy-Δ-9-tetrahydrocannabinol-glucuronide

et al. 2020

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(−)-Δ-9-tetrahydrocannabinol ((−)-Δ-9-THC) is the main psychoactive constituent in cannabis. During phase I metabolism, it is metabolized to (−)-11-hydroxy-Δ-9-tetrahydrocannabinol ((−)-11-OH-Δ-9-THC), which is psychoactive, and to (−)-11-nor-9-carboxy-Δ-9-tetrahydrocannabinol ((−)-Δ-9-THC-COOH), which is psychoinactive. It is glucuronidated during phase II metabolism. The biotransformation of (−)-Δ-9-tetrahydrocannabinol-glucuronide ((−)-Δ-9-THC-Glc) and (−)-11-nor-9-carboxy-Δ-9-tetrahydrocannabinol-glucuronide ((−)-Δ-9-THC-COOH-Glc) is well understood, which is mainly due to the availability of commercial reference standards. Since such a standardized reference is not yet available for (−)-11-hydroxy-Δ-9-tetrahydrocannabinol-glucuronide ((−)-11-OH-Δ-9-THC-Glc), its biotransformation is harder to study and the nature of the glucuronide bonding—alcoholic and/or phenolic—remains unclear. Consequently, the aim of this study was to investigate the biotransformation of (−)-11-OH-Δ-9-THC-Glc in vitro as well as in vivo and to identify the glucuronide by chemically synthesis of a reference standard. For in vitro analysis, pooled human S9 liver fraction was incubated with (−)-Δ-9-THC. Resulting metabolites were detected by high-performance liquid chromatography system coupled to a high-resolution mass spectrometer (HPLC-HRMS) with heated electrospray ionization (HESI) in positive and negative full scan mode. Five different chromatographic peaks of OH-Δ-9-THC-Glc have been detected in HESI positive and negative mode, respectively. The experiment set up according to Wen et al. indicates the two main metabolites being an alcoholic and a phenolic glucuronide metabolite. In vivo analysis of urine (n = 10) and serum (n = 10) samples from cannabis users confirmed these two main metabolites. Thus, OH-Δ-9-THC is glucuronidated at either the phenolic or the alcoholic hydroxy group. A double glucuronidation was not observed. The alcoholic (−)-11-OH-Δ-9-THC-Glc was successfully chemically synthesized and identified the main alcoholic glucuronide in vitro and in vivo. (−)-11-OH-Δ-9-THC-Glc is the first reference standard for direct identification and quantification. This enables future research to answer the question whether phenolic or alcoholic glucuronidation forms the predominant way of metabolism.

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Section: Investigation Of Inseparable (−)-11-oh-δ-9-thc-glc and G3supporting

confidence: 88%

Investigation of phase II metabolism of 11-hydroxy-Δ-9-tetrahydrocannabinol and metabolite verification by chemical synthesis of 11-hydroxy-Δ-9-tetrahydrocannabinol-glucuronide

et al. 2020

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“…An example of the stability of a typical N-carbamoyl glucuronide can be seen in a study by Gunduz et al (2010) where b-glucuronidase efficiently cleaved the conjugate to yield the parent; however, the conjugate was completely stable in the control incubation (buffer at 37 C for 4 h). Problematic acyl glucuronides typically have buffer half-lives of <2 h (Gunduz et al, 2018).…”

Section: Discussionmentioning

confidence: 99%

“…From a toxicity standpoint, the two most important reactions for acyl glucuronides are: 1) transacylation reactions with various endogenous nucleophiles to yield drug-labelled compounds/macromolecules, and 2) acyl migration that allows opening of the hexose ring and glycation and glycosylation of proteins by the resulting aldehyde (Gunduz et al, 2018). Both of these reactions lead to covalent binding with intracellular proteins that is thought to mediate the toxicity of the conjugates.…”

Section: Discussionmentioning

confidence: 99%

Metabolism and in vitro drug–drug interaction assessment of viloxazine

2020

Xenobiotica

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1. Viloxazine is currently being developed as a treatment for attention deficit/hyperactivity disorder (ADHD). The aim of these studies is to update the understanding of the rat and human metabolism and the in vitro drug-drug interaction profile of viloxazine to a degree where it meets current regulatory standards for such investigations. 2. In vivo absorption-distribution-metabolism-excretion (ADME) studies demonstrated that in humans 5-hydroxylation followed by glucuronidation is the major metabolic route. This route was also seen as a minor route in rats where the major route is O-deethylation with subsequent sulfation. 3. In humans, the 5-hydoxylation pathway is mediated by CYP2D6. An estimate for the fraction of the metabolism via this pathway suggests a PM/EM difference of <2-fold, making it highly unlikely that this will be an issue of clinical significance. 4. Viloxazine forms a unique N-carbamoyl glucuronide in humans. The chemical reactivity characteristics of this metabolite are similar to stable glucuronide conjugates and dissimilar from acyl glucuronides; therefore, it is regarded as a stable Phase II conjugate. 5. In vitro drug-drug interaction (DDI) testing indicates that viloxazine is not a significant inhibitor or inducer of CYPs and transporters with the exception of CYP1A2.

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“…UGT inhibition mechanisms have not been fully unraveled and RM involvement has never been suggested as a causative factor of TKI UGT1A1 inhibition. However, acyl glucuronides, through transacylation and glycation mechanisms, could potentially lead to TDI and toxicity as reported for several drugs bearing a carboxylic acid moiety . Thus, it is not unlikely that TKI metabolized to carboxylic acid derivatives could generate acyl glucuronides involved in their hepatotoxicity, but to the best of our knowledge, it has not been reported yet.…”

Section: Inhibition Of Udp‐glucuronosyltransferases By Tkimentioning

confidence: 83%

“…However, acyl glucuronides, through transacylation and glycation mechanisms, could potentially lead to TDI and toxicity as reported for several drugs bearing a carboxylic acid moiety. [150][151][152] Even though their underlying mechanisms are not fully elucidated, the involvement of RM resulting from the metabolic activation of structural alerts has been suspected. A chemical approach to preventing toxicities/DDI might be to avoid structural alerts to reduce RM formation but this strategy may also induce drug attrition in the early stage of drug development.…”

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confidence: 99%

Identifying the reactive metabolites of tyrosine kinase inhibitors in a comprehensive approach: Implications for drug‐drug interactions and hepatotoxicity

Paludetto

Puisset

Chatelut

et al. 2019

Medicinal Research Reviews

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Tyrosine kinase inhibitors (TKI) are small heterocyclic molecules targeting transmembrane and cytoplasmic tyrosine kinases that have met with considerable success in clinical oncology. TKI are associated with toxicities including liver injury that may be serious and even life‐threatening. Many of them require warnings in drug labeling against liver injury, and five of them have Black Box Warning (BBW) labels. Although drug‐induced liver injury is a matter of clinical and industrial concern, little is known about the underlying mechanisms that likely involve reactive metabolites (RM). RM are electrophiles or radicals originating from the metabolic activation of particular functional groups, known as structural alerts or toxicophores. RM are able to covalently bind to proteins and macromolecules, causing cellular damage and even cell death. If the adducted protein is the enzyme involved in RM formation, time‐dependent inhibition of the enzyme—also called mechanism‐based inhibition (MBI) or inactivation—can occur and lead to pharmacokinetic drug‐drug interactions. To mitigate RM liabilities, common practice in drug development includes avoiding structural alerts and assessing RM formation via RM trapping screens with soft and hard nucleophiles (glutathione, potassium cyanide, and methoxylamine) in liver microsomes. RM‐positive derivatives are further optimized to afford drug candidates with blocked or minimized bioactivation potential. However, different structural alerts are still commonly used scaffolds in drug design, including in TKI structures. This review focuses on the current state of knowledge of the relations among TKI structures, bioactivation pathways, RM characterization, and hepatotoxicity and cytochrome P450 MBI in vitro.

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New Perspectives on Acyl Glucuronide Risk Assessment in Drug Discovery: Investigation of In vitro Stability, In situ Reactivity, and Bioactivation

Cited by 13 publications

References 49 publications

Investigation of phase II metabolism of 11-hydroxy-Δ-9-tetrahydrocannabinol and metabolite verification by chemical synthesis of 11-hydroxy-Δ-9-tetrahydrocannabinol-glucuronide

Investigation of phase II metabolism of 11-hydroxy-Δ-9-tetrahydrocannabinol and metabolite verification by chemical synthesis of 11-hydroxy-Δ-9-tetrahydrocannabinol-glucuronide

Metabolism and in vitro drug–drug interaction assessment of viloxazine

Identifying the reactive metabolites of tyrosine kinase inhibitors in a comprehensive approach: Implications for drug‐drug interactions and hepatotoxicity

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