CYP-associated drug–drug interactions: A mission accomplished?

Prescription Patterns of Inducers and Inhibitors of Cytochrome P450 and Their Potential Drug Interactions in the Real World: A Cross-Sectional Study

INTRODUCTION

Both the induction and inhibition of cytochrome P450 are associated with multiple pharmacological interactions, which can lead to loss of efficacy or increase the risk of adverse drug reactions.

OBJECTIVE

The aim was to determine the prescription patterns of cytochrome P450-inducing and -inhibiting drugs and their contraindicated and major pharmacological interactions in a group of patients from Colombia.

METHODS

This cross-sectional observational study included patients who received drugs that induce or inhibit metabolism and examined their contraindicated and major pharmacological interactions. The patients were identified from a population-based database of drug dispensing. Patients were included between December 1 and December 31, 2021. Inhibitors and inducers of cytochrome P450 were classified based on FDA (Food and Drug Administration) guidelines. Drug interactions were identified using the Micromedex® database. Descriptive, bivariate and multivariable analysis was performed.

RESULTS

A total of 63,433 patients were analyzed. Antiseizure medications (35.9%) and antifungals (27.6%) were the most used inducers and inhibitors. A total of 30.1% of patients had potential contraindicated or greater interactions. The following factors were associated with a higher probability of presenting a potential pharmacological interaction: being male (OR 1.14; 95% CI 1.10-1.19), aged 18-39 years (OR 1.77; 95% CI 1.67-1.89) or 40-64 years (OR 1.64; 95% CI 1.56-1.72), having neurological diseases (OR 1.28; 95% CI 1.21-1.35), having psychiatric diseases (OR 3.84; 95% CI 3.58-4.13), having rheumatologic diseases (OR 1.32; 95% CI 1.23-1.41), receiving comedications with statins (OR 1.14; 95% CI 1.08-1.19), receiving comedications with analgesics (OR 1.33; 95% CI 1.27-1.38), receiving comedications with antiparasitics (OR 2.88; 95% CI 2.66-3.11) and an increase in the number of medications (OR 1.24; 95% CI 1.23-1.25).

CONCLUSION

Among the users of cytochrome P450 inhibitors and inducers, potential contraindications and greater interactions are very common, especially in men under 65 years of age with comorbidities and polypharmacy.

Induction of hepatic CYP3A4 expression by cholesterol and cholic acid: Alterations of gene expression, microsomal activity, and pharmacokinetics

Human cytochrome P450 3A4 (CYP3A4) is a drug-metabolizing enzyme that is abundantly expressed in the liver and intestine. It is an important issue whether compounds of interest affect the expression of CYP3A4 because more than 30% of commercially available drugs are metabolized by CYP3A4. In this study, we examined the effects of cholesterol and cholic acid on the expression level and activity of CYP3A4 in hCYP3A mice that have a human CYP3A gene cluster and show human-like regulation of the coding genes. A normal diet (ND, CE-2), CE-2 with 1% cholesterol and 0.5% cholic acid (HCD) or CE-2 with 0.5% cholic acid was given to the mice. The plasma concentrations of cholesterol, cholic acid and its metabolites in HCD mice were higher than those in ND mice. In this condition, the expression levels of hepatic CYP3A4 and the hydroxylation activities of triazolam, a typical CYP3A4 substrate, in liver microsomes of HCD mice were higher than those in liver microsomes of ND mice. Furthermore, plasma concentrations of triazolam in HCD mice were lower than those in ND mice. In conclusion, our study suggested that hepatic CYP3A4 expression and activity are influenced by the combination of cholesterol and cholic acid in vivo.

Development of novel HEPT analogs featuring significantly improved anti-resistance potency against HIV-1 through chemical space exploration of the tolerant region I

Our recent great interest in developing 1-[(2-hydroxyethoxy)methyl]-6-(phenylthio)thymine (HEPT) analogs for HIV therapy identified a potent non-nucleoside reverse transcriptase inhibitor (NNRTI) 3 (EC50 = 0.01681 μM), but its therapeutic efficacy was limited by its poor anti-resistance potency. This prompted us to search for potential HEPT analogs with broad-spectrum activities, leading to the generation of a series of novel HEPT analogs through exploring the chemical space of the solvent - protein interface. Encouraging improvements in anti-resistance efficacy were observed in some of these analogs, with the most promising compound 7 g being 3 to 26 - fold more potent than 3 against five mutant strains (E138K, Y181C, L100I, K103N, and Y188L). This analog surpassed the activity and selectivity of compound 3 by approximately 2-fold (EC50 = 0.007468 μM, SI = 4260). Furthermore, it was found to demonstrate feeble inhibition of CYP and hERG in vitro, and no in vivo acute toxicity. This study will further enrich the structure-activity relationships (SARs) of the HEPT scaffold, providing new guidance for the development of NNRTIs.

Single-cell metabolic profiling reveals subgroups of primary human hepatocytes with heterogeneous responses to drug challenge

BACKGROUND

Xenobiotics are primarily metabolized by hepatocytes in the liver, and primary human hepatocytes are the gold standard model for the assessment of drug efficacy, safety, and toxicity in the early phases of drug development. Recent advances in single-cell genomics demonstrate liver zonation and ploidy as main drivers of cellular heterogeneity. However, little is known about the impact of hepatocyte specialization on liver function upon metabolic challenge, including hepatic metabolism, detoxification, and protein synthesis.

RESULTS

Here, we investigate the metabolic capacity of individual human hepatocytes in vitro. We assess how chronic accumulation of lipids enhances cellular heterogeneity and impairs the metabolisms of drugs. Using a phenotyping five-probe cocktail, we identify four functional subgroups of hepatocytes responding differently to drug challenge and fatty acid accumulation. These four subgroups display differential gene expression profiles upon cocktail treatment and xenobiotic metabolism-related specialization. Notably, intracellular fat accumulation leads to increased transcriptional variability and diminishes the drug-related metabolic capacity of hepatocytes.

CONCLUSIONS

Our results demonstrate that, upon a metabolic challenge such as exposure to drugs or intracellular fat accumulation, hepatocyte subgroups display different and heterogeneous transcriptional responses.

Inter-species differences between humans and other mammals in the in vitro metabolism of carbofuran and the role of human CYP enzymes

This study investigated the metabolic transformation of carbofuran in seven species of mammals using LC-MS/MS and liver microsomes. The results revealed species-specific differences in metabolite formation, indicating the potential role of metabolic pathways in toxicity and risk assessment. The majority of carbofuran was metabolized through the 3-hydroxycarbofuran pathway, with the highest levels observed in dogLM and the lowest in humanLM. Further analysis was conducted to investigate the human cytochrome P450-mediated metabolism of carbofuran, with CYP3A4 being found to be the most efficient enzyme with the highest contribution to the 3-hydroxycarbofuran pathway. Inhibition of CYP3A4 with ketoconazole resulted in a substantial decrease in carbofuran metabolism. In addition, carbofuran exhibited inhibitory effects on human CYP3A4 and CYP2B6, demonstrating the potential for carbofuran to interact with these enzymes. The findings highlight the importance of in vitro screening for metabolic processes and provide insights into the biotransformation of carbofuran.

Evaluation potential effects of Picroside II on cytochrome P450 enzymes in vitro and in vivo

ETHNOPHARMACOLOGY RELEVANCE

Picrorhiza scrophulariiflora Pennell, a well-known Chinese herb, has been traditionally utilized as an antioxidant and anti-inflammatory agent. One of its main bioactive components is Picroside II, a glycoside derivative. However, there is limited information on the effects of Picroside II on the activity of cytochrome P450 (CYP) enzymes nor on potential herb-drug interactions are rarely studied.

AIM OF THE STUDY

The purpose of the study was to investigate the effects of Picroside II on the activity of cytochrome P450 enzymes in vitro and in vivo and its potential herb-drug interactions.

MATERIALS AND METHODS

Specific probe substrates were employed to assess the effect of Picroside II on the activity of P450 enzymes. The inhibitory effects of Picroside II on CYP enzymes were assayed both in human (i.e., 1A, 2C9, 2C19, 2D6, 2E1, and 3A) and rat (i.e., 1A, 2C6/11, 2D1, 2E1, and 3A) liver microsomes in vitro. The inductive effects were investigated in rats following oral gavage of 2.5 mg/kg and 10 mg/kg Picroside II. A specific Ultra Performance Liquid Chromatography-Tandem Mass Spectrometry (UPLC-MS/MS) method was developed to determine the formation of specific metabolites.

RESULTS

Enzyme inhibition results showed that Picroside II (0.5-200 μM) had no evident inhibitory effects on rat and human liver microsomes in vitro. Interestingly, the administration of multiple doses of 10 mg/kg Picroside II inhibited the activity of CYP2C6/11 by reducing the rate of formation of 4-hydroxydiclofenac and 4-hydroxymephenytoin, while Picroside II at 2.5 mg/kg increased the activity of CYP3A by promoting the formation of 1-hydroxymidazolam and 6-hydroxychlorzoxazone in rats. In addition, there were negligible effects on CYP1A, CYP2D1, and CYP2E1 in rats.

CONCLUSIONS

The results indicated that Picroside II modulated the activities of CYP enzymes and was involved in CYP2C and CYP3A medicated herb-drug interactions. Therefore, careful monitoring is necessary when Picroside II is used in combination with related conventional drugs.

Physiologically based pharmacokinetic combined JAK2 occupancy modelling to simulate PK and PD of baricitinib with kidney transporter inhibitors and in patients with hepatic/renal impairment

PURPOSE

Our aim is to build a physiologically based pharmacokinetic and JAK2 occupancy model (PBPK-JO) to simultaneously predict pharmacokinetic (PK) and pharmacodynamic (PD) changes of baricitinib (BAR) in healthy humans when co-administrated with kidney transporters OAT3 and MATE2-K inhibitors, and in patients with hepatic and renal impairment.

METHODS

Probenecid and vandetanib were selected as OAT3 and MATE2-K competitive inhibitors, respectively. The PBPK-JO model was built using physicochemical and biochemical properties of BAR, and then verified by observed clinical PK. Finally, the model was applied to determine optimal dosing regimens in various clinical situations.

RESULTS

Here, we have successfully simulated PK and JAK2 occupancy profiles in humans by PBPK-JO model. Moreover, this modelling reproduced every observed PK data, and every mean relative deviation (MRD) was below 2. The simulation suggested that PK of BAR had a significant change (2.22-fold increase), however PD only had a slight increase of 1.14-fold. Additionally, the simulation also suggested that vandetanib was almost unlikely to affect the PK and PD of BAR. In simulations of hepatic and renal impairment patients, the predictions suggested that significant changes in the PK and PD of BAR occurred. However, there was a lower fold increase in JAK2 occupancy than in PK in patients relative to healthy individuals.

CONCLUSION

Administration dose adjustment of BAR when co-administrated with OAT3 inhibitors or in patients with hepatic or renal impairment should combine PK and PD changes of BAR, instead of only considering PK alteration.

An approach for mixture testing and prioritization based on common kinetic groups

In light of an ever-increasing exposure to chemicals, the topic of potential mixture toxicity has gained increased attention, particularly as the toxicological toolbox to address such questions has vastly improved. Routinely toxicological risk assessments will rely on the analysis of individual compounds with mixture effects being considered only in those specific cases where co-exposure is foreseeable, for example for pesticides or food contact materials. In the field of pesticides, active substances are summarized in so-called cumulative assessment groups (CAG) which are primarily based on their toxicodynamic properties, that is, respective target organs and mode of action (MoA). In this context, compounds causing toxicity by a similar MoA are assumed to follow a model of dose/concentration addition (DACA). However, the respective approach inherently falls short of addressing cases where there are dissimilar or independent MoAs resulting in wider toxicokinetic effects. Yet, the latter are often the underlying cause when effects deviate from the DACA model. In the present manuscript, we therefore suggest additionally to consider toxicokinetic effects (especially related to xenobiotic metabolism and transporter interaction) for the grouping of substances to predict mixture toxicity. In line with the concept of MoA-based CAGs, we propose common kinetics groups (CKGs) as an additional tool for grouping of chemicals and mixture prioritization. Fundamentals of the CKG concept are discussed, along with challenges for its implementation, and methodological approaches and examples are explored.

Characterization of furathiocarb metabolism in in vitro human liver microsomes and recombinant cytochrome P450 enzymes

Furathiocarb is a carbamate insecticide detected in ecosystems. Its main metabolite carbofuran has been alluded to affect birth outcomes and disturb hormone levels in humans. The metabolism of furathiocarb in humans has not been characterized. The metabolism studies were performed using hepatic microsomes from ten donors and fifteen human cDNA-expressed CYPs. The initial screening and identification of the metabolites were performed by LC-TOF. Quantifications and fragmentations were performed by LC/MS-MS. Furathiocarb was metabolized to eight phase I metabolites via two general pathways, carbofuran metabolic pathway and furathiocarb oxidation pathway. Six metabolites in the carbofuran metabolic pathway (carbofuran, 3-hydroxycarbofuran, 3-ketocarbofuran, 3-keto-7-phenolcarbofuran, 3-hydroxy-7-phenolcarbofuran, and 7-phenolcarbofuran) were identified with the help of authentic standards. The two unidentified metabolites in the furathiocarb oxidation pathway are probably hydroxylated and sulfoxidated derivatives of furathiocarb. The carbofuran metabolic pathway was more predominant than the furathiocarb oxidation pathway, ratios ranged from 24- to 115-fold in a 10-donor panel of hepatic microsomes. On the basis of recombinant CYP studies, the carbofuran pathway was dominated by CYP3A4 (95.9%); contributions by CYP1A2 (1.3%) and CYP2B6 (2.0%) were minor. The minor furathiocarb oxidation pathway was catalyzed by CYP2C19 and CYP2D6 (hydroxylated/sulfoxidated metabolite A) and by CYP3A5, CYP3A4 and CYP2A6 (metabolite B). High and significant correlation between carbofuran metabolic pathway and CYP3A4 marker activities (midazolam-1'-hydroxylation and omeprazole-sulfoxidation) were observed. Ketoconazole, a CYP3A4-inhibitor, inhibited the carbofuran pathway by 32–86% and hydroxylated/sulfoxidated metabolite-B formations by 41–62%. The data suggest that in humans, the carbofuran metabolic pathway is dominant, and CYP3A4 is the major enzyme involved. These results provide useful scientific information for furathiocarb risk assessment in humans.

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Eight Phase I metabolites were detected by LC-TOF-MS/MS.

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The carbofuran pathway was more rapid than the furathiocarb oxidation pathway

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The carbofuran pathway was dominated by CYP3A4 (96%).

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Ketoconazole inhibited the carbofuran pathway by 32–86%.

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The findings provide useful scientific information for furathiocarb risk assessment in humans.

Aryl hydrocarbon receptor as a DNA methylation reader in the stress response pathway

The aryl hydrocarbon receptor (AhR) mediates various cellular responses upon exposure to exogenous and endogenous stress factors. In these responses, AhR plays a dual role as a stress sensor for detecting various AhR ligands and as a transcription factor that upregulates the expression of downstream effector genes, such as those encoding drug-metabolizing enzymes. As a transcription factor, it selectively binds to the unmethylated form of a specific sequence called the xenobiotic responsive element (XRE). We suggest that AhR is a novel DNA methylation reader, unlike classical methylation readers, such as methyl-CpG-binding protein 2, which binds to methylated sequences. Under physiological conditions of continuous exposure to endogenous AhR ligands, such as kynurenine, methylation states of the individual target XREs must be strictly regulated to select and coordinate the expression of downstream genes responsible for maintaining homeostasis in the body. In contrast, long-term exposure to AhR ligands frequently leads to changes in the methylation patterns around the XRE sequence. These data indicate that AhR may contribute to the adaptive cellular response to various stresses by modulating DNA methylation. Thus, the DNA methylation profile of AhR target genes should be dynamically controlled through a balance between robustness and flexibility under both physiological and stress conditions. AhR is a pivotal player in the regulation of stress response as it shows versatility by functioning as a stress sensor, methylation reader, and putative methylation modulator.

Effect of CYP3A4 Inhibitors and Inducers on Pharmacokinetics and Pharmacodynamics of Saxagliptin and Active Metabolite M2 in Humans Using Physiological-Based Pharmacokinetic Combined DPP-4 Occupancy

We aimed to develop a physiological-based pharmacokinetic and dipepidyl peptidase 4 (DPP-4) occupancy model (PBPK-DO) characterized by two simultaneous simulations to predict pharmacokinetic (PK) and pharmacodynamic changes of saxagliptin and metabolite M2 in humans when coadministered with CYP3A4 inhibitors or inducers. Ketoconazole, delavirdine, and rifampicin were selected as a CYP3A4 competitive inhibitor, a time-dependent inhibitor, and an inducer, respectively. Here, we have successfully simulated PK profiles and DPP-4 occupancy profiles of saxagliptin in humans using the PBPK-DO model. Additionally, under the circumstance of actually measured values, predicted results were good and in line with observations, and all fold errors were below 2. The prediction results demonstrated that the oral dose of saxagliptin should be reduced to 2.5 mg when coadministrated with ketoconazole. The predictions also showed that although PK profiles of saxagliptin showed significant changes with delavirdine (AUC 1.5-fold increase) or rifampicin (AUC: a decrease to 0.19-fold) compared to those without inhibitors or inducers, occupancies of DPP-4 by saxagliptin were nearly unchanged, that is, the administration dose of saxagliptin need not adjust when there is coadministration with delavirdine or rifampicin.

Recent developments in predicting CYP-independent metabolism

As lead optimization efforts have successfully reduced metabolic liabilities due to cytochrome P450 (CYP)-mediated metabolism, there has been an increase in the frequency of involvement of non-CYP enzymes in the metabolism of investigational compounds. Although there have been numerous notable advancements in the characterization of non-CYP enzymes with respect to their localization, reaction mechanisms, species differences and identification of typical substrates, accurate prediction of non-CYP-mediated clearance, with a particular emphasis with the difficulties in accounting for any extrahepatic contributions, remains a challenge. The current manuscript comprehensively summarizes the recent advancements in the prediction of drug metabolism and the in vitro to in vitro extrapolation of clearance for substrates of non-CYP drug metabolizing enzymes.