Use of in vitro and in vivo data to estimate the likelihood of metabolic pharmacokinetic interactions

Metabolism of m-CPP, trazodone, nefazodone, and etoperidone: clinical and forensic aspects

Trazodone, nefazodone, and etoperidone are classified as atypical antidepressants belonging to the phenylpiperazine class. These antidepressants are primarily metabolized by CYP3A4 into m-chlorophenylpiperazine (mCPP), which was initially employed in veterinary medicine but has gained widespread use as a recreational drug globally despite legal restrictions in numerous countries. The active metabolite, mCPP, exerts various neuropsychiatric effects by interacting with serotonin receptors. It primarily exhibits nonselective agonistic properties with some antagonistic effects and influences temperature, behavior, and hormone release via central 5-HT receptors. The surge in mCPP popularity can be attributed to its MDMA-like effects, and its initial misidentification as an MDMA substitute facilitated its unregulated distribution worldwide. This review aims to comprehensively explore the pharmacokinetics and pharmacodynamics of these compounds, with a specific focus on the forensic challenges posed by mCPP as a metabolite of antidepressants. The primary objective is to delineate the consumption patterns of these compounds in laboratory settings, making this review crucial for understanding the intricate nuances of these drugs in forensic contexts.

Enzalutamide: Understanding and Managing Drug Interactions to Improve Patient Safety and Drug Efficacy

Enzalutamide is an oral androgen receptor signaling inhibitor utilized in the treatment of men with prostate cancer. It is a moderate inducer of the cytochrome P450 (CYP) enzymes CYP2C9 and CYP2C19, and a strong inducer of CYP3A4. It was also shown to be a mild inhibitor of the efflux transporter P-glycoprotein in patients with prostate cancer. Enzalutamide is primarily metabolized by CYP3A4 and CYP2C8. The risk of enzalutamide drug interactions arises primarily when it is coadministered with other drugs that interact with these CYPs, including CYP3A4. In this review, we begin by providing an overview of enzalutamide including its dosing, use in special populations, pharmacokinetics, changes to its prescribing information, and potential for interaction with coadministered drugs. Enzalutamide interactions with drugs from a wide range of medication classes commonly prescribed to patients with prostate cancer are described, including oral androgen deprivation therapy, agents used to treat a range of cardiovascular diseases, antidiabetic drugs, antidepressants, anti-seizure medications, common urology medications, analgesics, proton pump inhibitors, immunosuppressants, and antigout drugs. Enzalutamide interactions with common vitamins and supplements are also briefly discussed. This review provides a resource for healthcare practitioners and patients that will help provide a basis for the understanding and management of enzalutamide drug-drug interactions to inform decision making, improve patient safety, and optimize drug efficacy.

Risk factors for irritable bowel syndrome: A review

Irritable bowel syndrome (IBS) is one of the most common diseases of the digestive tract from the group of disorders of interaction in the gut-brain axis. IBS has a negative impact of on patients' quality of life and the significant social and economic burden of the disease due to the low effectiveness of available treatment strategies, which are only symptomatic, without impacting factors and mechanisms of intestinal dysfunction. From this perspective, it is critical to study the factors contributing to the onset and persistence of IBS symptoms to improve the early diagnosis of the disease and implement targeted prevention technology in at-risk groups. The objective of this paper is to systematize data on the main risk factors for IBS, including hereditary predisposition, stress and psycho-emotional state, diet and eating habits, and acute intestinal infections.

Hydrocodone, Oxycodone, and Morphine Metabolism and Drug-Drug Interactions

Awareness of drug interactions involving opioids is critical for patient treatment as they are common therapeutics used in numerous care settings, including both chronic and disease-related pain. Not only do opioids have narrow therapeutic indexes and are extensively used, but they have the potential to cause severe toxicity. Opioids are the classical pain treatment for patients who suffer from moderate to severe pain. More importantly, opioids are often prescribed in combination with multiple other drugs, especially in patient populations who typically are prescribed a large drug regimen. This review focuses on the current knowledge of common opioid drug-drug interactions (DDIs), focusing specifically on hydrocodone, oxycodone, and morphine DDIs. The DDIs covered in this review include pharmacokinetic DDI arising from enzyme inhibition or induction, primarily due to inhibition of cytochrome p450 enzymes (CYPs). However, opioids such as morphine are metabolized by uridine-5'-diphosphoglucuronosyltransferases (UGTs), principally UGT2B7, and glucuronidation is another important pathway for opioid-drug interactions. This review also covers several pharmacodynamic DDI studies as well as the basics of CYP and UGT metabolism, including detailed opioid metabolism and the potential involvement of metabolizing enzyme gene variation in DDI. Based upon the current literature, further studies are needed to fully investigate and describe the DDI potential with opioids in pain and related disease settings to improve clinical outcomes for patients. SIGNIFICANCE STATEMENT: A review of the literature focusing on drug-drug interactions involving opioids is important because they can be toxic and potentially lethal, occurring through pharmacodynamic interactions as well as pharmacokinetic interactions occurring through inhibition or induction of drug metabolism.

Molecular Idiosyncratic Toxicology of Drugs in the Human Liver Compared with Animals: Basic Considerations

Drug induced liver injury (DILI) occurs in patients exposed to drugs at recommended doses that leads to idiosyncratic DILI and provides an excellent human model with well described clinical features, liver injury pattern, and diagnostic criteria, based on patients assessed for causality using RUCAM (Roussel Uclaf Causality Assessment Method) as original method of 1993 or its update of 2016. Overall, 81,856 RUCAM based DILI cases have been published until mid of 2020, allowing now for an analysis of mechanistic issues of the disease. From selected DILI cases with verified diagnosis by using RUCAM, direct evidence was provided for the involvement of the innate and adapted immune system as well as genetic HLA (Human Leucocyte Antigen) genotypes. Direct evidence for a role of hepatic immune systems was substantiated by (1) the detection of anti-CYP (Cytochrome P450) isoforms in the plasma of affected patients, in line with the observation that 65% of the drugs most implicated in DILI are metabolized by a range of CYP isoforms, (2) the DIAIH (drug induced autoimmune hepatitis), a subgroup of idiosyncratic DILI, which is characterized by high RUCAM causality gradings and the detection of plasma antibodies such as positive serum anti-nuclear antibodies (ANA) and anti-smooth muscle antibodies (ASMA), rarely also anti-mitochondrial antibodies (AMA), (3) the effective treatment with glucocorticoids in part of an unselected RUCAM based DILI group, and (4) its rare association with the immune-triggered Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN) caused by a small group of drugs. Direct evidence of a genetic basis of idiosyncratic DILI was shown by the association of several HLA genotypes for DILI caused by selected drugs. Finally, animal models of idiosyncratic DILI mimicking human immune and genetic features are not available and further search likely will be unsuccessful. In essence and based on cases of DILI with verified diagnosis using RUCAM for causality evaluation, there is now substantial direct evidence that immune mechanisms and genetics can account for idiosyncratic DILI by many but not all implicated drugs, which may help understand the mechanistic background of the disease and contribute to new approaches of therapy and prevention.

Simplifying the Extended Clearance Concept Classification System (EC3S) to Guide Clearance Prediction in Drug Discovery

PURPOSE

The Extended Clearance Concept Classification System was established as a development-stage tool to provide a framework for identifying fundamental mechanism(s) governing drug disposition in humans. In the present study, the applicability of the EC3S in drug discovery has been investigated. In its current format, the EC3S relies on low-throughput hepatocyte uptake data, which are not frequently generated in a discovery setting.

METHODS

A relationship between hepatocyte uptake clearance and MDCK permeability was first established along with intrinsic clearance from human liver microsomes. The performance of this approach was examined by categorizing 64 drugs into EC3S classes and comparing the predicted major elimination pathway(s) to that observed in humans. As an extension of the work, the ability of the simplified EC3S to predict human systemic clearance based on intrinsic clearance generated using in-vitro metabolic systems was evaluated.

RESULTS

The assessment enabled the use of MDCK permeability and unscaled unbound intrinsic clearance to generate cut-off criteria to categorize compounds into four EC3S classes: Class 12ab, 2cd, 34ab, and 34cd, with major elimination mechanism(s) assigned to each class. The predictivity analysis suggested that systemic clearance could generally be predicted within threefold for EC3S class 12ab and 34ab compounds. For classes 2cd and 34cd, systemic clearance was poorly predicted using in-vitro systems explored in this study.

CONCLUSION

Collectively, our simplified classification approach is expected to facilitate the identification of mechanism(s) involved in drug elimination, faster resolution of in-vitro to in-vivo disconnects, and better design of mechanistic pharmacokinetic studies in drug discovery.

Pharmacogenomics in Asians: Differences and similarities with other human populations

INTRODUCTION

Various pharmacogenomic (PGx) variants differ widely in different ethnicities. and clinical outcomes associated with these variants may also be substantially varied. Literature was searched in different databases, i.e. PubMed, ScienceDirect, Web of Science, and PharmGKB, from inception to 30 June 2022 for this review.

AREAS COVERED

Certain PGx variants were distinctly varied in Asian populations compared to the other human populations, e.g. CYP2C19*2,*3,*17; CYP2C9*2,*3; CYP2D6*4,*5,*10,*41; UGT1A1*6,*28; HLA-B*15:02, HLA-B*15:21, HLA-B*58:01, and HLA-A*31:01. However, certain other variants do not vary greatly between Asian and other ethnicities, e.g. CYP3A5*3; ABCB1, and SLCO1B1*5. As evident in this review, the risk of major adverse cardiovascular events (MACE) was much stronger in Asian patients taking clopidogrel and who inherited the CYP2C19 loss-of-function alleles, e.g. CYP2C19*2 and*3, when compared to the western/Caucasian patients. Additionally, the risk of carbamazepine-induced severe cutaneous adverse drug reactions (SCARs) for the patients inheriting HLA-B*15:02 and HLA-B*15:21 alleles varied significantly between Asian and other ethnicities. In contrast, both Caucasian and Asian patients inheriting the SLCO1B1*5 variant possessed a similar magnitude of muscle toxicity, i.e. myopathy.

EXPERT OPINION

Asian countries should take measures toward expanding PGx research, as well as initiatives for the purposes of obtaining clinical benefits from this newly evolving and economically viable treatment model.

The Role of CYP3A in Health and Disease

CYP3A is an enzyme subfamily in the cytochrome P450 (CYP) superfamily and includes isoforms CYP3A4, CYP3A5, CYP3A7, and CYP3A43. CYP3A enzymes are indiscriminate toward substrates and are unique in that these enzymes metabolize both endogenous compounds and diverse xenobiotics (including drugs); almost the only common characteristic of these compounds is lipophilicity and a relatively large molecular weight. CYP3A enzymes are widely expressed in human organs and tissues, and consequences of these enzymes' activities play a major role both in normal regulation of physiological levels of endogenous compounds and in various pathological conditions. This review addresses these aspects of regulation of CYP3A enzymes under physiological conditions and their involvement in the initiation and progression of diseases.

Cytochrome P450 enzymes and metabolism of drugs and neurotoxins within the mammalian brain

Cytochrome P450 enzymes (CYPs) that metabolize xenobiotics are expressed and active in the brain. These CYPs contribute to the metabolism of many centrally acting compounds, including clinically used drugs, drugs of abuse, and neurotoxins. Although CYP levels are lower in the brain than in the liver, they may influence central substrate and metabolite concentrations, which could alter resulting centrally-mediated responses to these compounds. Additionally, xenobiotic metabolizing CYPs are highly variable due to genetic polymorphisms and regulation by endogenous and xenobiotic molecules. In the brain, these CYPs are sensitive to xenobiotic induction. As a result, CYPs in the brain vary widely, including among humans, and this CYP variation may influence central metabolism and resulting response to centrally acting compounds. It has been demonstrated, using experimental manipulation of CYP activity in vivo selectively within the brain, that CYP metabolism in the brain alters central substrate and metabolite concentrations, as well as drug response and neurotoxic effects. This suggests that variability in xenobiotic metabolizing CYPs in the human brain may meaningfully contribute to individual differences in response to, and effects of, centrally acting drugs and neurotoxins. This chapter will provide an overview of CYP expression in the brain, endogenous- and xenobiotic-mediated CYP regulation, and the functional impact of CYP-mediated metabolism of drugs and neurotoxins in the brain, with a focus on experimental approaches in mice, rats, and non-human primates, and a discussion regarding the potential role of xenobiotic metabolizing CYPs in the human brain.

Oxazepam Detected in Urine 79 Days After Withdrawal of Diazepam: A Case Report

Patients suffering from substance use disorder, including for instance benzodiazepines, may have comorbidity with attention deficit hyperactivity disorder (ADHD). Centrally acting stimulants play an important role in the treatment of ADHD. Before such treatment can be initiated, withdrawal of benzodiazepines may be necessary. Urine testing is the preferred method for monitoring adherence in benzodiazepine withdrawal, but there is a lack of studies reporting detection time. Here, we report a case of a 30-year-old woman with substance use disorder and ADHD who had detectable metabolites of diazepam 79 days after withdrawal. To our knowledge, no cases with detection time equivalent to this have previously been published. This case report serves as an example that clinicians may need to consider interindividual pharmacokinetic characteristics when interpreting the results of urine drug tests, and that a positive urine test may still be consistent with abstinence from a certain drug. In the current case, a high body mass index and a genetic polymorphism gave a reasonable explanation for the prolonged detection of diazepam metabolites.

Identification of C5-NH2 Modified Oseltamivir Derivatives as Novel Influenza Neuraminidase Inhibitors with Highly Improved Antiviral Activities and Favorable Druggability

Our previous efforts have proved that modifications targeting the 150-cavity of influenza neuraminidase can achieve more potent and more selective inhibitors. In this work, four subseries of C5-NH₂ modified oseltamivir derivatives were designed and synthesized to explore every region inside the 150-cavity. Among them, compound 23d was exceptionally potent against the whole panel of Group-1 NAs with IC₅₀ values ranging from 0.26 to 0.73 nM, being 15-53 times better than oseltamivir carboxylate (OSC) and 7-11 times better than zanamivir. In cellular assays, 23d showed more potent or equipotent antiviral activities against corresponding virus strains compared to OSC with no cytotoxicity. Furthermore, 23d exhibited high metabolic stability in human liver microsomes (HLM) and low inhibitory effect on main cytochrome P450 enzymes. Notably, 23d displayed favorable druggability in vivo and potent antiviral efficacy in the embryonated egg model and mice model. Overall, 23d appears to be a promising candidate for the treatment of influenza virus infection.

Clinically Relevant Interactions with Anti-Infectives on Intensive Care Units-A Multicenter Delphi Study

Patients in intensive care units (ICUs) are at high risk of drug–drug interactions (DDIs) due to polypharmacy. Little is known about type and frequency of DDIs within German ICUs. Clinical pharmacists’ interventions (PI) recorded in a national database (ADKA-DokuPIK) were filtered for ICU patients. Binary DDIs involving ≥1 anti-infective agent with >1 database entry were selected. A modified two-step Delphi process with a group of senior hospital pharmacists was employed to evaluate selected DDIs for clinical relevance by using a five-point scale and to develop guidance for clinical practice. In total, 16,173 PI were recorded, including 1836 (11%) DDIs in the ICU setting. Of the latter, 41% (756/1836) included ≥1 anti-infective agent, 32% (590/1836) were binary DDIs, and 25% (455/1836) were listed at least twice. This translates into 88 different DDIs, 74% (65/88) of which were rated as being clinically relevant by our expert panel. The majority of DDIs (76% [67/88]) included macrolides, antifungals, or fluoroquinolones. This percentage was even higher in DDIs being rated as clinically relevant by the experts (85% [55/65]). It is noted that an inter-professional discussion and approach is needed in the individual patient management of DDIs. The guidance developed might be a tool for decision support.

A Perspective on Synthetic Biology in Drug Discovery and Development-Current Impact and Future Opportunities

The global impact of synthetic biology has been accelerating, because of the plummeting cost of DNA synthesis, advances in genetic engineering, growing understanding of genome organization, and explosion in data science. However, much of the discipline's application in the pharmaceutical industry remains enigmatic. In this review, we highlight recent examples of the impact of synthetic biology on target validation, assay development, hit finding, lead optimization, and chemical synthesis, through to the development of cellular therapeutics. We also highlight the availability of tools and technologies driving the discipline. Synthetic biology is certainly impacting all stages of drug discovery and development, and the recognition of the discipline's contribution can further enhance the opportunities for the drug discovery and development value chain.

Mechanism of idiosyncratic drug induced liver injury (DILI): unresolved basic issues

Clinical features of idiosyncratic drug induced liver injury (DILI) are well described in cases that have been assessed for causality using the Roussel Uclaf Causality Assessment Method (RUCAM), but our understanding of the mechanistic steps leading to injury is fragmentary. The difficulties describing mechanistic events can be traced back to the lack of an animal model of experimental idiosyncratic DILI that can mimic the genetic requirements of human idiosyncratic DILI. However, immune tolerance plays a dominant role in the immune response of the liver, and impairment of immune tolerance with immune checkpoint inhibitors increases DILI in both humans and animals. This may provide one method to study the individual steps involved. In general. the human DILI liver is a secret keeper providing little insight into what occurs in the diseased organ. Sufficient evidence exists that most idiosyncratic cases are mediated by the adaptive immune system, which depends on stimulation of the innate immune system, but the triggering factors are unknown. It is attractive to hypothesize that the gut microbiome plays a role; however, it is very difficult to study. Similarly, exosomes are likely to play an important role in communication between hepatic cells and the immune system, but there is a lack of data on blood exosomes in affected patients. Reactive metabolites are likely to play an important role. This is supported by the current analysis, which revealed an association between metabolism by cytochrome P450 and drugs most commonly involved in causing idiosyncratic DILI with causality verified by RUCAM. Circumstantial evidence suggests that reactive oxygen species (ROS) generated by cytochrome P450 could be responsible for the initial steps of injury, but details are unknown. In conclusion, most of the mechanistic steps leading to idiosyncratic DILI remain unclear.

Translational control of enzyme scavenger expression with toxin-induced micro RNA switches

Biological computation requires in vivo control of molecular behavior to progress development of autonomous devices. miRNA switches represent excellent, easily engineerable synthetic biology tools to achieve user-defined gene regulation. Here we present the construction of a synthetic network to implement detoxification functionality. We employed a modular design strategy by engineering toxin-induced control of an enzyme scavenger. Our miRNA switch results show moderate synthetic expression control over a biologically active detoxification enzyme molecule, using an established design protocol. However, following a new design approach, we demonstrated an evolutionarily designed miRNA switch to more effectively activate enzyme activity than synthetically designed versions, allowing markedly improved extrinsic user-defined control with a toxin as inducer. Our straightforward new design approach is simple to implement and uses easily accessible web-based databases and prediction tools. The ability to exert control of toxicity demonstrates potential for modular detoxification systems that provide a pathway to new therapeutic and biocomputing applications.

Discovery and development of novel pyrimidine and pyrazolo/thieno-fused pyrimidine derivatives as potent and orally active inducible nitric oxide synthase dimerization inhibitor with efficacy for arthritis

In order to discover and develop drug-like anti-inflammatory agents against arthritis, based on "Hit" we found earlier and to overcome drawbacks of toxicity, twelve series of total 89 novel pyrimidine, pyrazolo[4,3-d]pyrimidine and thieno[3,2-d]pyrimidine derivatives were designed, synthesized and screened for their anti-inflammatory activity against NO and toxicity for normal liver cells (LO2). Relationships of balance toxicity and activity have been summarized through multi-steps, and title compounds 22o, 22l were found to show lower toxicity (against LO2: IC₅₀ = 2934, 2301 μM, respectively) and potent effect against NO release (IR = 98.3, 97.67%, at 10 μM, respectively). Furthermore, compound 22o showed potent iNOS inhibitory activity with value of IC₅₀ is 0.96 μM and could interfere stability and formation of the active dimeric iNOS. It's anti-inflammatory activity in vivo was assessed by AIA rat model. Furthermore, the results of metabolic stability, CYP, PK study in vivo, acute toxicity study and subacute toxicity assessment indicated this compound had good drug-like properties for treatment.

Identification of biomarkers to diagnose diseases and find adverse drug reactions by metabolomics

Metabolomics has been widely used for investigating the biological functions of disease expression and has the potential to discover biomarkers in circulating biofluids or tissue extracts that reflect in phenotypic changes. Metabolic profiling has advantages because of the use of unbiased techniques, including multivariate analysis, and has been applied in pharmacological studies to predict therapeutic and adverse reactions of drugs, which is called pharmacometabolomics (PMx). Nuclear magnetic resonance (NMR)- and mass spectrometry (MS)-based metabolomics has contributed to the discovery of recent disease biomarkers; however, the optimal strategy for the study purpose must be selected from many established protocols, methodologies and analytical platforms. Additionally, information on molecular localization in tissue is essential for further functional analyses related to therapeutic and adverse effects of drugs in the process of drug development. MS imaging (MSI) is a promising technology that can visualize molecules on tissue surfaces without labeling and thus provide localized information. This review summarizes recent uses of MS-based global and wide-targeted metabolomics technologies and the advantages of the MSI approach for PMx and highlights the PMx technique for the biomarker discovery of adverse drug effects.

Precision Dosing Management with Intelligent Computing in Digital Health

Pediatric dosing is not only critical for successful pediatric trials in drug development but also paramount to safety and effective treatment at bedside. Due to the complex pharmacokinetic of children compared to adults, several challenges are posed in managing dosing precisely during drug development and after drug approval to clinicians. In particular, given the real-world practice, understanding the impact of development on the dose-exposure-response relationship is essential in optimizing the dosing to children of different ages. In this paper we propose a novel intelligent computing framework to examine how the growth and maturation create size- and age-dependent variability in pharmacokinetics and pharmacodynamics, and summarize the use of modeling-based approaches for dose finding in pediatric drug development, allowing clinicians to anticipate probable treatment effects and to have a higher likelihood of achieving optimal dose regimens early, as well as reducing the drug development cycling time and cost.

Plasma protein binding, metabolism, reaction phenotyping and toxicokinetic studies of fenarimol after oral and intravenous administration in rats

Fenarimol (FNL), an organic chlorinated fungicide, is widely used in agriculture for protection from fungal spores and fungi. Despite being an endocrine disruptor, no toxicokinetic data is reported for this fungicide. In the present work, we determined the plasma protein binding, metabolic pathways and toxicokinetics of FNL in rats. In vitro binding of FNL to rat and human plasma proteins was ∼90%, suggesting that FNL is a highly protein bound fungicide. The predicted in vivo hepatic clearance of FNL in rats and humans was estimated to be 36.71 and 14.39 mL/min/kg, respectively, indicating it to be an intermediate clearance compound. Reaction phenotyping assay showed that CYP3A4 mainly contributed to the overall metabolism of FNL. The oral toxicokinetic study of FNL in rats at no observed adverse effect level dose (1 mg/kg) showed maximum plasma concentration (C _max) of 33.97 ± 4.45 ng/mL at 1 h (T _max). The AUC_0-∞ obtained was 180.18 ± 17.76 h*ng/mL, whereas, the t _1/2 was ∼4.74 h. Following intravenous administration, FNL displayed a clearance of 42.48 mL/min/kg which was close to the predicted in vivo hepatic clearance. The absolute oral bioavailability of FNL at 1 mg/kg dose in rats was 45.25%. FNL at 10 mg/kg oral dose exhibited non-linear toxicokinetics with greater than dose-proportional increase in the systemic exposure (AUC_0-∞ 8270.53 ± 1798.59 h*ng/mL).

In-Silico Modeling in Drug Metabolism and Interaction: Current Strategies of Lead Discovery

BACKGROUND

Drug metabolism is a complex mechanism of human body systems to detoxify foreign particles, chemicals, and drugs through bio alterations. It involves many biochemical reactions carried out by invivo enzyme systems present in the liver, kidney, intestine, lungs, and plasma. After drug administration, it crosses several biological membranes to reach into the target site for binding and produces the therapeutic response. After that, it may undergo detoxification and excretion to get rid of the biological systems. Most of the drugs and its metabolites are excreted through kidney via urination. Some drugs and their metabolites enter into intestinal mucosa and excrete through feces. Few of the drugs enter into hepatic circulation where they go into the intestinal tract. The drug leaves the liver via the bile duct and is excreted through feces. Therefore, the study of total methodology of drug biotransformation and interactions with various targets is costly.

METHODS

To minimize time and cost, in-silico algorithms have been utilized for lead-like drug discovery. Insilico modeling is the process where a computer model with a suitable algorithm is developed to perform a controlled experiment. It involves the combination of both in-vivo and in-vitro experimentation with virtual trials, eliminating the non-significant variables from a large number of variable parameters. Whereas, the major challenge for the experimenter is the selection and validation of the preferred model, as well as precise simulation in real physiological status.

RESULTS

The present review discussed the application of in-silico models to predict absorption, distribution, metabolism, and excretion (ADME) properties of drug molecules and also access the net rate of metabolism of a compound.

CONCLUSION

It helps with the identification of enzyme isoforms; which are likely to metabolize a compound, as well as the concentration dependence of metabolism and the identification of expected metabolites. In terms of drug-drug interactions (DDIs), models have been described for the inhibition of metabolism of one compound by another, and for the compound-dependent induction of drug-metabolizing enzymes.

ADME Prediction with KNIME: Development and Validation of a Publicly Available Workflow for the Prediction of Human Oral Bioavailability

In silico prediction of human oral bioavailability is a relevant tool for the selection of potential drug candidates and for the rejection of those molecules with less probability of success during the early stages of drug discovery and development. However, the high variability and complexity of oral bioavailability and the limited experimental data in the public domain have mainly restricted the development of reliable in silico models to predict this property from the chemical structure. In this study we present a KNIME automated workflow to predict human oral bioavailability of new drug and drug-like molecules based on five machine learning approaches combined into an ensemble model. The workflow is freely accessible and allows the quick and easy prediction of oral bioavailability for new molecules. Users do not require any knowledge or advanced experience in machine learning or statistical modeling to automatically obtain their predictions, increasing the potential use of the present proposal.

Impact of the Selective Orexin-1 Receptor Antagonist ACT-539313 on the Pharmacokinetics of the CYP3A Probe Drug Midazolam in Healthy Male Subjects

ACT-539313 is a potent and selective orexin-1 receptor antagonist. CYP3A is the major cytochrome P450 (CYP) enzyme involved in the metabolism and clearance of ACT-539313 in man. The main objective of this study was to investigate the effect of ACT-539313 on the pharmacokinetics of orally administered midazolam. Thereby, this single-center, open-label, fixed-sequence study investigated the CYP3A interaction potential of ACT-539313 following single- (on day 2) and repeated-dose (on day 11) twice-daily administration of 200 mg ACT-539313. Exposure to midazolam was higher during concomitant administration of single as well as after repeated doses of ACT-539313 over 10 days compared to midazolam alone (day 1). In the presence of ACT-539313, the geometric mean ratio of the maximum plasma concentration and the area under the plasma concentration-time curve from time 0 to 24 hours increased by 1.18- and 1.79-fold on day 2, and by 2.13- and 4.54-fold on day 11, respectively. A similar outcome was also shown in the additionally evaluated urinary 6β-hydroxycortisol/cortisol ratio (6β-CR), as the geometric mean ratio of the 6β-CR showed a decrease to 0.78 on day 2 and to 0.61 on day 11. The most commonly reported adverse events (AEs) included somnolence and headache. All AEs were transient and of mild intensity. No treatment-related effects on vital signs, clinical laboratory, and electrocardiogram were observed. In summary, the observed corresponding decrease of both the validated, exogenous (midazolam/1-hydroxymidazolam ratio) and a frequently used endogenous (6β-CR) marker of CYP3A activity is indicative of CYP3A inhibition occurring after ACT-539313 treatment.

Toward precision medicine in pediatric population using cytochrome P450 phenotyping approaches and physiologically based pharmacokinetic modeling

The activity of drug-metabolizing enzymes (DME) shows high inter- and intra-individual variability. Genetic polymorphisms, exposure to drugs, and environmental toxins are known to significantly alter DME expression. In addition, the activity of these enzymes is highly age-dependent due to maturation processes that occur during development. Currently, there is a vast choice of phenotyping methods in adults using exogenous probes to characterize the activity of these enzymes. However, this can hardly be applied to children since it requires the intake of non-therapeutic xenobiotics. In addition, sampling may be challenging in the pediatric population for a variety of reasons: limited volume (e.g., blood), inappropriate sampling methods for age (e.g., urine), and metric requiring invasive or multiple blood samples. This review covers the main existing methods that can be used in the pediatric population to determine DME activity, with a particular focus on cytochrome P450 enzymes. Less invasive tools are described, including phenotyping using endogenous probes. Finally, the potential of pediatric model-informed precision dosing using physiologically based pharmacokinetic modeling is discussed.

Generation of functional hepatocyte-like cells from human bone marrow mesenchymal stem cells by overexpression of transcription factor HNF4α and FOXA2

BACKGROUND

Our previous study showed that overexpression of hepatocyte nuclear factor 4α (HNF4α) could directly promote mesenchymal stem cells (MSCs) to differentiate into hepatocyte-like cells. However, the efficiency of hepatic differentiation remains low. The purpose of our study was to establish an MSC cell line that overexpressed HNF4α and FOXA2 genes to obtain an increased hepatic differentiation efficiency and hepatocyte-like cells with more mature hepatocyte functions.

METHODS

Successful establishment of high-level HNF4α and FOXA2 co-overexpression in human induced hepatocyte-like cells (hiHep cells) was verified by flow cytometry, immunofluorescence and RT-PCR. Measurements of albumin (ALB), urea, glucose, indocyanine green (ICG) uptake and release, cytochrome P450 (CYP) activity and gene expression were used to analyze mature hepatic functions of hiHep cells.

RESULTS

hiHep cells efficiently express HNF4α and FOXA2 genes and proteins, exhibit typical epithelial morphology and acquire mature hepatocyte-like cell functions, including ALB secretion, urea production, ICG uptake and release, and glycogen storage. hiHep cells can be activated by CYP inducers. The percentage of both ALB and α-1-antitrypsin (AAT)-positive cells was approximately 72.6%. The expression levels of hepatocyte-specific genes (ALB, AAT, and CYP1A1) and liver drug transport-related genes (ABCB1, ABCG2, and SLC22A18) in hiHep cells were significantly higher than those in MSCs-Vector cells. The hiHep cells did not form tumors after subcutaneous xenograft in BALB/c nude mice after 2 months.

CONCLUSION

This study provides an accessible, feasible and efficient strategy to generate hiHep cells from MSCs.

Effect of Drug Combination on Omeprazole Metabolism by Cytochrome P450 2C19 in Helicobacter pylori Eradication Therapy

Helicobacter pylori (H. pylori) infection is common and can result in gastric and duodenal ulcers, and in some cases, gastric lymphoma and cancer. Omeprazole (OMP)-in combination with clarithromycin (CLR), amoxicillin (AMX), tinidazole (TND), or metronidazole (MET)-is used in double or triple combination therapy for eradication of H. pylori. However, the roles of the drugs other than OMP are not clearly understood. Therefore, in the present study, we aimed to investigate any effects of these drugs on OMP metabolism by wild-type CYP2C19 using spectroscopy and enzyme kinetics. The dissociation constants (K_d) for CYP2C19 with OMP, CLR, AMX, TND, and MET were 8.6, 126, 156, 174, and 249 µM, respectively. The intrinsic clearance of OMP was determined to be 355 mL/min/µmol of CYP2C19. Metabolism of OMP was significantly inhibited by 69, 66, 28, and 40% in the presence of CLR, TND, AMX, and MET, respectively. Moreover, the combination of CLR and TND resulted in 76% inhibition of OMP metabolism, while the combination of AMX and MET resulted in 48% inhibition of OMP metabolism. Both combinations of drugs not only have antibacterial effects, but also enhance the effect of OMP by inhibiting its metabolism by CYP2C19. These results indicate that drug-drug interactions of co-administered drugs can cause complex effects, providing a basis for OMP dose adjustment when used in combination therapy for H. pylori eradication.

Benzoyl indoles with metabolic stability as reversal agents for ABCG2-mediated multidrug resistance

Ko143, a potent ABCG2 inhibitor that reverses multidrug resistance in cancer, cannot be used clinically due to its unsuitable metabolic stability. We identified benzoyl indoles as reversal agents that reversed ABCG2-mediated multidrug resistance (MDR), with synthetic tractability and enhanced metabolic stability compared to Ko143. Bisbenzoyl indole 2 and monobenzoyl indole 8 significantly increased the accumulation of mitoxantrone (MX) in ABCG2-overexpressing NCI-H460/MX20 cells, and sensitized NCI-H460/MX20 cells to mitoxantrone. Mechanistic studies were conducted by [³H]-MX accumulation assay, Western blot analysis, immunofluorescence analysis and ABCG2 ATPase assay. The results revealed that the reversal efficacies of compounds 2 and 8 were not due to an alteration in the expression level or localization of ABCG2 in ABCG2-overexpressing cell lines. Instead, compounds 2 and 8 significantly stimulated the ATP hydrolysis of ABCG2 transporter, suggesting that these compounds could be competitive substrates of ABCG2 transporter. Overall, the results of our study indicated that compounds 2 and 8 significantly reversed ABCG2-mediated MDR by blocking the efflux of anticancer drugs.

Exploring the Chemical Space of Cytochrome P450 Inhibitors Using Integrated Physicochemical Parameters, Drug Efficiency Metrics and Decision Tree Models

The cytochrome P450s (CYPs) play a central role in the metabolism of various endogenous and exogenous compounds including drugs. CYPs are vulnerable to inhibition and induction which can lead to adverse drug reactions. Therefore, insights into the underlying mechanism of CYP450 inhibition and the estimation of overall CYP inhibitor properties might serve as valuable tools during the early phases of drug discovery. Herein, we present a large data set of inhibitors against five major metabolic CYPs (CYP1A2, CYP2C9, CYP2C19, CYP2D6 and CYP3A4) for the evaluation of important physicochemical properties and ligand efficiency metrics to define property trends across various activity levels (active, efficient and inactive). Decision tree models for CYP inhibition were developed with an accuracy >90% for both the training set and 10-folds cross validation. Overall, molecular weight (MW), hydrogen bond acceptors/donors (HBA/HBD) and lipophilicity (clogP/logPo/w) represent important physicochemical descriptors for CYP450 inhibitors. However, highly efficient CYP inhibitors show mean MW, HBA, HBD and logP values between 294.18–482.40,5.0–8.2,1–7.29 and 1.68–2.57, respectively. Our results might help in optimization of toxicological profiles associated with new chemical entities (NCEs), through a better understanding of inhibitor properties leading to CYP-mediated interactions.

Getting high with the most high: Entheogens in the Old Testament

This article collects evidence from psychopharmacology, scripture, and archeology to explore several preparations for consumption described in the Old Testament: Manna, Showbread, the Holy Ointment, and the Tabernacle Incense. The Ointment and the Incense are herbal preparations used by the priestly caste to facilitate a direct experience of the Israelite God. A wide variety of psychoactive components are found in these preparations, including GABA-receptor agonists and modulators, opioid receptor agonists, and other agents. They are normally broken down by the body’s enzymes, and therefore orally inactive, but the Holy Ointment also contains inhibitors specific to the enzymes in question. The preparations indicate that the ancient Israelites had a profound understanding of synergism, and the way they are consumed and the taboos around them are highly suggestive of their use as psychoactive agents.

Effect of an anxiolytic botanical containing Souroubea sympetala and Platanus occidentalis on in-vitro diazepam human cytochrome P450-mediated metabolism

OBJECTIVES

A novel anxiolytic natural health product (NHP) containing Souroubea sympetala and Platanus occidentalis is available for the companion animal market and is currently being developed for clinical evaluation. Addressing the risk of potential NHP-drug interactions, this study investigated S. sympetala and P. occidentalis plant extracts, and their identified bioactive compounds, for effects on the activity of cytochrome P450 (CYP) isozymes and the metabolism of the conventional anti-anxiety medication diazepam.

METHODS

Souroubea sympetala and P. occidentalis extracts, a 1 : 1 blend of the two extracts, and five triterpenes were tested for inhibitory effects on human recombinant CYP3A4, CYP2D6, CYP2C9 and CYP2C19 activity using a fluorometric plate assay. Direct effects on the metabolism of diazepam were evaluated using human liver microsomes with drug and metabolite quantification by ultra-high-pressure liquid chromatography and mass spectroscopy.

KEY FINDINGS

The active substances betulinic acid (BA) and ursolic acid (UA) strongly inhibited CYP3A4 activity while UA and lupeol moderately inhibited CYP2C19. All extracts exhibited strong activity against the tested isozymes at 50-100 μg/ml. BA and all plant extracts blocked the formation of major diazepam metabolites.

CONCLUSIONS

Betulinic acid, UA and both the extracts and blended product are expected to affect the metabolism of diazepam when given in high dose.

Understanding the relevance of herb-drug interaction studies with special focus on interplays: a prerequisite for integrative medicine

Integrative medicine refers to the blending of conventional and evidence-based complementary medicines and therapies with the aim of using the most appropriate of either or both modalities for ultimate patient benefits. One of the major hurdles for the same is the chances of potential herb–drug interactions (HDIs). These HDIs could be beneficial or harmful, or even fatal; therefore, a thorough understanding of the eventualities of HDIs is essential so that a successful integration of the modern and complementary alternative systems of medicine could be achieved. Here, we summarize all the important points related to HDIs, including types, tools/methods for study, and prediction of the HDIs, along with a special focus on interplays between drug metabolizing enzymes and transporters. In addition, this article covers future perspective, with a focus on background endogenous players of interplays and approaches to predict the drug–disease–herb interactions so as to fetch the desired effects of these interactions.

Mechanism-based inactivation of cytochrome P450 2D6 by chelidonine

Chelidonine (CHE) is a major bioactive constituent of greater celandine, a plant used in traditional herbal medicines. CHE has widely been used as an analgesic in clinical settings. We evaluated the inhibitory effects of CHE on human cytochrome P450 enzymes. CHE produced time-, concentration-, and NADPH-dependent inhibition of CYP2D6, with K _I and k _inact values of 20.49 μM and 11.05 min ^-1 , respectively. Approximately 76% of CYP2D6 activity was suppressed after 9 minute incubation with CHE (50 μM). The loss of enzyme activity was not restored following dialysis. The estimated partition ratio of the inactivation was about 156. Quinidine, a competitive inhibitor of CYP2D6, attenuated the CHE-mediated enzyme inactivation, while glutathione and catalase/superoxide dismutase did not markedly ameliorate the inhibitory effect. Upon oxidation using potassium ferricyanide, the 15.1% activity of CYP2D6 was restored. These findings indicate that CHE acted as a mechanism-based inactivator of CYP2D6 and the observed effects may induce potential drug-drug interactions.

New insights for risks of chlorophenols (CPs) exposure: Inhibition of UDP-glucuronosyltransferases (UGTs)

Chlorophenols (CPs) are important pollutants extensively utilized in industry, agriculture and forestry. The present study aims to determine the inhibition of CPs on the activity of the important phase II drug-metabolizing enzymes (DMEs) UDP-glucuronosyltransferases (UGTs). 100 μM of fourteen CPs were used for preliminary screening using in vitro incubation. Furthermore, half inhibition concentration (IC₅₀) and inhibition kinetics were determined for CPs with significant inhibition towards UGT isoforms. In silico docking was used to explain the inhibition difference among CPs. Multiple UGT isoforms were inhibited by CPs. In silico docking showed that higher free binding energy due to hydrophobic interactions of 2.4-Dichlorophenol (2.4-DCP) or 4-Chloro-3-methylphenol (4C3MP) with UGT1A9 contributed to stronger inhibition potential of 2.4-Dichlorophenol (2.4-DCP) or 4-Chloro-3-methylphenol (4C3MP) towards UGT1A9 than 4-CP. Pentachlorophenol (PCP) was chosen as the representative CPs to determine the IC₅₀ value towards UGT1A6, UGT1A9 and UGT2B7. IC₅₀ was calculated to be 0.33 μM, 0.24 μM and 31.35 μM for the inhibition of PCP towards UGT1A6, UGT1A9 and UGT2B7. PCP was demonstrated to show competitive inhibition towards UGT1A6, UGT1A9 and UGT2B7, and the inhibition kinetic parameters (Ki) was calculated to be 0.18 μM, 0.01 μM and 5.37 μM for the inhibition of PCP towards UGT1A6, UGT1A9 and UGT2B7. All these information will be beneficial for elucidating the risk of CPs exposure from a new perspective.

Application of Q2MM to predictions in stereoselective synthesis

Quantum-Guided Molecular Mechanics (Q2MM) can be used to derive transition state force fields (TSFFs) that allow the fast and accurate predictions of stereoselectivity for a wide range of catalytic enantioselective reactions. The basic ideas behind the derivation of TSFFs using Q2MM are discussed and the steps involved in obtaining a TSFF using the Q2MM code, publically available at github.com/q2mm, are shown. The applicability for a range of reactions, including several non-standard applications of Q2MM, is demonstrated. Future developments of the method are also discussed.

Current knowledge of microRNA-mediated regulation of drug metabolism in humans

INTRODUCTION

Understanding the factors causing inter- and intra-individual differences in drug metabolism potencies is required for the practice of personalized or precision medicine, as well as for the promotion of efficient drug development. The expression of drug-metabolizing enzymes is controlled by transcriptional regulation by nuclear receptors and transcriptional factors, epigenetic regulation, such as DNA methylation and histone acetylation, and post-translational modification. In addition to such regulation mechanisms, recent studies revealed that microRNAs (miRNAs), endogenous ~22-nucleotide non-coding RNAs that regulate gene expression through the translational repression and degradation of mRNAs, significantly contribute to post-transcriptional regulation of drug-metabolizing enzymes. Areas covered: This review summarizes the current knowledge regarding miRNAs-dependent regulation of drug-metabolizing enzymes and transcriptional factors and its physiological and clinical significance. We also describe recent advances in miRNA-dependent regulation research, showing that the presence of pseudogenes, single-nucleotide polymorphisms, and RNA editing affects miRNA targeting. Expert opinion: It is unwavering fact that miRNAs are critical factors causing inter- and intra-individual differences in the expression of drug-metabolizing enzymes. Consideration of miRNA-dependent regulation would be a helpful tool for optimizing personalized and precision medicine.

Computational modeling of human oral bioavailability: what will be next?

INTRODUCTION

The oral route is the most convenient way of administrating drugs. Therefore, accurate determination of oral bioavailability is paramount during drug discovery and development. Quantitative structure-property relationship (QSPR), rule-of-thumb (RoT) and physiologically based-pharmacokinetic (PBPK) approaches are promising alternatives to the early oral bioavailability prediction. Areas covered: The authors give insight into the factors affecting bioavailability, the fundamental theoretical framework and the practical aspects of computational methods for predicting this property. They also give their perspectives on future computational models for estimating oral bioavailability. Expert opinion: Oral bioavailability is a multi-factorial pharmacokinetic property with its accurate prediction challenging. For RoT and QSPR modeling, the reliability of datasets, the significance of molecular descriptor families and the diversity of chemometric tools used are important factors that define model predictability and interpretability. Likewise, for PBPK modeling the integrity of the pharmacokinetic data, the number of input parameters, the complexity of statistical analysis and the software packages used are relevant factors in bioavailability prediction. Although these approaches have been utilized independently, the tendency to use hybrid QSPR-PBPK approaches together with the exploration of ensemble and deep-learning systems for QSPR modeling of oral bioavailability has opened new avenues for development promising tools for oral bioavailability prediction.

Ancestry-Adjusted Vitamin D Metabolite Concentrations in Association With Cytochrome P450 3A Polymorphisms

We investigated the association between genetic polymorphisms in cytochrome P450 (CYP2R1, CYP24A1, and the CYP3A family) with nonsummer plasma concentrations of vitamin D metabolites (25-hydroxyvitamin D3 (25(OH)D3) and proportion 24,25-dihydroxyvitamin D3 (24,25(OH)2D3)) among healthy individuals of sub-Saharan African and European ancestry, matched on age (within 5 years; n = 188 in each ancestral group), in central suburban Pennsylvania (2006-2009). Vitamin D metabolites were measured using high-performance liquid chromatography with tandem mass spectrometry. Paired multiple regression and adjusted least-squares mean analyses were used to test for associations between genotype and log-transformed metabolite concentrations, adjusted for age, sex, proportion of West-African genetic ancestry, body mass index, oral contraceptive (OC) use, tanning bed use, vitamin D intake, days from summer solstice, time of day of blood draw, and isoforms of the vitamin D receptor (VDR) and vitamin D binding protein. Polymorphisms in CYP2R1, CYP3A43, vitamin D binding protein, and genetic ancestry proportion remained associated with plasma 25(OH)D3 after adjustment. Only CYP3A43 and VDR polymorphisms were associated with proportion 24,25(OH)2D3. Magnitudes of association with 25(OH)D3 were similar for CYP3A43, tanning bed use, and OC use. Significant least-squares mean interactions (CYP2R1/OC use (P = 0.030) and CYP3A43/VDR (P = 0.013)) were identified. A CYP3A43 genotype, previously implicated in cancer, is strongly associated with biomarkers of vitamin D metabolism. Interactive associations should be further investigated.

ROLE OF CYTOCHROME P450S IN THE GENERATION AND METABOLISM OF REACTIVE OXYGEN SPECIES

The cytochrome P450 (CYP) enzymes are a diverse group of heme monooxygenases that, through the course of their reaction cycle, contribute to cellular reactive oxygen species (ROS). CYP enzymes play a crucial role in human physiology and are involved in drug and xenobiotic metabolism as well as biosynthesis of endogenous molecules and are expressed throughout the human body. However, during the course of the CYP catalytic cycle, ROS can be generated through uncoupling of the enzymatic cycle. ROS is known to modify endogenous molecules, included lipids, proteins, and nucleic acids, which can lead to cell damage and death and contribute to disease development. ROS has been implicated in a wide range of diseases and conditions, including cancer and ageing, but ROS also play a role in the normal physiological functions in the cell. Here, we discuss specific examples whereby ROS generated by CYPs contribute to or protect against various phenomena, such as hyperoxic lung injury, oxidative hepatic toxicity, formation of DNA adducts from lipid peroxidation products. We have also discussed the mechanistic roles of CYP enzymes belonging to various families, and their effect on cellular ROS production, in relation to normal cellular function as well as disease pathophysiology.

Potential anticancer role of colchicine-based derivatives: an overview

Colchicine, the main alkaloid of the poisonous plant meadow saffron (Colchicum autumnale L.), is a classical drug used for the treatment of gout and familial Mediterranean fever. Although colchicine is not clinically used to treat cancer because of toxicity, it exerts antiproliferative effects through the inhibition of microtubule formation by blocking the cell cycle at the G2/M phase and triggering apoptosis. Colchicine can still be used as a lead compound for the generation of potential anticancer drugs. Thus, numerous analogues of colchicine have been synthesized in the hope of developing novel, useful drugs with more favourable pharmacological profiles. Several colchicine semisynthetics are less toxic than colchicine and research is being carried out on effective, less toxic colchicine semisynthetic formulations with potential drug-delivery strategies directly targeting multiple solid cancers. This review focuses on the anticancer role of some of colchicine-based derivatives and their therapeutic importance.

Effect of Korean Red Ginseng extracts on drug-drug interactions

Background

Ginseng has been the subject of many experimental and clinical studies to uncover the diverse biological activities of its constituent compounds. It is a traditional medicine that has been used for its immunostimulatory, antithrombotic, antioxidative, anti-inflammatory, and anticancer effects. Ginseng may interact with concomitant medications and alter metabolism and/or drug transport, which may alter the known efficacy and safety of a drug; thus, the role of ginseng may be controversial when taken with other medications.

Methods

We extensively assessed the effects of Korean Red Ginseng (KRG) in rats on the expression of enzymes responsible for drug metabolism [cytochrome p450 (CYP)] and transporters [multiple drug resistance (MDR) and organic anion transporter (OAT)] in vitro and on the pharmacokinetics of two probe drugs, midazolam and fexofenadine, after a 2-wk repeated administration of KRG at different doses.

Results

The results showed that 30 mg/kg KRG significantly increased the expression level of CYP3A11 protein in the liver and 100 mg/kg KRG increased both the mRNA and protein expression of OAT1 in the kidney. Additionally, KRG significantly increased the mRNA and protein expression of OAT1, OAT3, and MDR1 in the liver. Although there were no significant changes in the metabolism of midazolam to its major metabolite, 1′-hydroxymidazolam, KRG significantly decreased the systemic exposure of fexofenadine in a dose-dependent manner.

Conclusion

Because KRG is used as a health supplement, there is a risk of KRG overdose; thus, a clinical trial of high doses would be useful. The use of KRG in combination with P-glycoprotein substrate drugs should also be carefully monitored.

Quantitative prediction of the extent of drug-drug interaction using a physiologically based pharmacokinetic model that includes inhibition of drug metabolism determined in cryopreserved hepatocytes

1. A physiologically based pharmacokinetic (PBPK) model that includes inhibition constant evaluated in cryopreserved hepatocytes was used to predict drug-drug interactions (DDIs) between orally administered nifedipine, a CYP substrate, and fluconazole or ketoconazole, CYP inhibitors, in rats. 2. The Kp,uu, ratio of unbound inhibitor concentration in liver ([I]liver,u) to that in plasma ([I]sys,u), of fluconazole and ketoconazole was 1.0 and 13.0, indicating that ketoconazole accumulates in liver. The ratios of inhibition constants in rat liver microsomes (Ki,mic,u) to that in rat cryopreserved hepatocytes (Ki,hep,u) for fluconazole and ketoconazole were 1.5 and 25.5, which were similar to the Kp,uu and suggested that cryopreserved hepatocytes could mimic the hepatic accumulation of inhibitors. 3. The increases in AUC of nifedipine predicted by the minimal PBPK model using [I]liver,u/Ki,mic,u and [I]sys,u/Ki,hep,u were within 1.5-fold of the observed values for both inhibitors, whereas the model using [I]sys,u/Ki,mic,u underestimated the AUC increase caused by ketoconazole 21-fold. 4. These results indicated that hepatic accumulation factor of an inhibitor is required for a precise DDI projection and that cryopreserved hepatocytes would be useful to obtain the Ki including hepatic accumulation factor. It was demonstrated that PBPK model using Ki,hep,u could be a valuable approach for quantitative DDI projection.

A non-destructive BFCOD assay for in vivo measurement of cytochrome P450 3A (CYP3A) enzyme activity in fish embryos and larvae

There is increasing interest in quantifying the exposure and effects of anthropogenic contaminants in fish. Determination of exposures in wild fish is routinely performed, but methods to investigate potential effects are less established. One of the most relevant approaches would be the use of in vivo assays, but existing assays are often limited to in vitro determination of enzyme activity. Many pharmaceuticals and some persistent pollutants activate, and are metabolized by cytochrome P4503A (CYP3A), which make it a relevant and desirable target for biomarker research. We altered the established 7-benzyloxy-4-trifluoromethylcoumarin-O-debenzylation (BFCOD) in vitro protocol for CYP3A activity determination, developing a rapid and inexpensive method to measure in vivo (and in ovo) CYP3A activity in two fish systems: Gulf killifish (Fundulus grandis) and zebrafish (Danio rerio) early life stages. Even with very low concentrations of 7-benzyloxy-4-trifluoromethyl coumarin (BFC, 0.06 µM or 20 µg/L), we were able to detect significant induction in CYP3A activity in embryos of F. grandis, as well as in larvae of D. rerio in response to benzo[a]pyrene (BaP) and fluoranthene (FL) exposures. Because of concerns regarding the possible contribution of CYP1A to BFCOD activity from previous research, we have used a CYP1A post-translational inhibitor (FL) in order to calculate the contribution of CYP1A to the BFCOD assay. We also dosed with benzo[k]fluoranthene (BkF) and showed significant induction of CYP1A activity, with no concurrent increase in CYP3A activity. In this paper, we have taken an established in vitro CYP3A activity assay, and utilized the reaction in a novel way to allow for the non-destructive determination of CYP3A. In summary, we describe a sensitive, cheap, fast and easy modified BFCOD assay for in ovo and in vivo determination of CYP3A activity for use in moderate throughput early-life-stage fish experiments.

Worldwide Distribution of Cytochrome P450 Alleles: A Meta-analysis of Population-scale Sequencing Projects

Genetic polymorphisms in cytochrome P450 (CYP) genes can result in altered metabolic activity toward a plethora of clinically important medications. Thus, single nucleotide variants and copy number variations in CYP genes are major determinants of drug pharmacokinetics and toxicity and constitute pharmacogenetic biomarkers for drug dosing, efficacy, and safety. Strikingly, the distribution of CYP alleles differs considerably between populations with important implications for personalized drug therapy and healthcare programs. To provide a global distribution map of CYP alleles with clinical importance, we integrated whole‐genome and exome sequencing data from 56,945 unrelated individuals of five major human populations. By combining this dataset with population‐specific linkage information, we derive the frequencies of 176 CYP haplotypes, providing an extensive resource for major genetic determinants of drug metabolism. Furthermore, we aggregated this dataset into spectra of predicted functional variability in the respective populations and discuss the implications for population‐adjusted pharmacological treatment strategies.