Effect of recombinant CYP3A4 variants and interaction on imatinib metabolism in vitro.

The aim of this study was to investigate the catalytic activity of 26 Cytochrome P450 3A4 (CYP3A4) variants and drug interactions on imatinib metabolism in recombinant insect microsomes. This study was designed with an appropriate incubation system and carried out in the constant temperature water. By using ultra-performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) to measure the quantities of its metabolite N-desmethyl imatinib, to elucidate the impacts of the CYP3A4 genetic polymorphism and drug interactions on the metabolism of imatinib. Consequently, as compared to CYP3A4.1, the intrinsic clearance (CLint) values of the variations were dramatically changed, rising from 2.34 % to 120.57 %. CYP3A4.14 showed an increase in CLint in comparison to CYP3A4.1, and the remaining 24 variants demonstrated decreases in catalytic activity for the metabolism of imatinib. In addition, the metabolism of imatinib was decreased to varied degrees by ketoconazole, itraconazole, and fluconazole in CYP3A4.1 and CYP3A4.18. Moreover, most of CYP3A4 variants showed similar trend of enzyme activity under different substrates of imatinib and cabozantinib, except 6 variants (CYP3A4.3,.4,.10,.15,.29 and.31). The first study of the effects of 26 CYP3A4 variants on imatinib metabolism will contribute to the clinical evaluation of imatinib and help personalize therapy in clinical settings.

Guiding the starting dose of the once-daily formulation of tacrolimus in "de novo" adult renal transplant patients: a population approach.

Aims: The once-daily extended-release tacrolimus formulation (ER-Tac) has demonstrated similar efficacy and safety to the twice-daily immediate-release formulation (IR-Tac), but few population-based pharmacokinetic models have been developed in de novo kidney transplant patients to optimize doses. Therefore, this study aimed i) at developing a population pharmacokinetic model for ER-Tac in de novo adult kidney transplant patients ii) and identifying genetic factors and time-varying covariates predictive of pharmacokinetic variability to guide tacrolimus dosage during the early post-transplant period. Methods: A total of 1,067 blood tacrolimus concentrations from 138 kidney transplant patients were analyzed. A total of 29 out of 138 patients were intensively sampled for 24 h on the day 5 post-transplantation; meanwhile, for the remaining patients, concentrations were collected on days 5, 10, and 15 after transplantation. Tacrolimus daily doses and genetic and demographic characteristics were retrieved from the medical files. Biochemistry time-varying covariates were obtained on different days over the pharmacokinetic (PK) study. A simultaneous PK analysis of all concentrations was carried out using the non-linear mixed-effects approach with NONMEM 7.5. Results: A two-compartment model with linear elimination and delayed absorption best described the tacrolimus pharmacokinetics. Between-patient variability was associated with oral blood clearance (CL/F) and the central compartment distribution volume (Vc/F). Tacrolimus concentrations standardized to a hematocrit value of 45% significantly improved the model (p < 0.001). This method outperformed the standard covariate modeling of the hematocrit-blood clearance relationship. The effect of the CYP3A5 genotype was statistically (p < 0.001) and clinically significant on CL/F. The CL/F of patients who were CYP3A5*1 carriers was 51% higher than that of CYP3A5*1 non-carriers. Age also influenced CL/F variability (p < 0.001). Specifically, CL/F declined by 0.0562 units per each increased year from the value estimated in patients who were 60 years and younger. Conclusion: The 36% between-patient variability in CL/F was explained by CYP3A5 genotype, age, and hematocrit. Hematocrit standardization to 45% explained the variability of tacrolimus whole-blood concentrations, and this was of utmost importance in order to better interpret whole-blood tacrolimus concentrations during therapeutic drug monitoring. The dose requirements of CYP3A5*/1 carriers in patients aged 60 years or younger would be highest, while CYP3A5*/1 non-carriers older than 60 years would require the lowest doses.

Tug of war between clozapine and CYP450 inducers: A case report.

The management of schizoaffective disorder bipolar type often involves a combination of pharmacotherapy and psychotherapy. Clozapine, an effective antipsychotic for treatment-resistant schizophrenia, and oxcarbazepine, a mood stabilizer, is a commonly prescribed medication. We present a case report of a 56-year-old male with schizoaffective disorder bipolar type who experienced subtherapeutic clozapine levels despite dose adjustments, leading to deteriorating symptoms. Oxcarbazepine, a weak CYP450 inducer, likely contributed to the subtherapeutic levels. Additionally, the pharmacogenetic analysis revealed a CYP1A2 *1F/*1F genotype, indicating normal activity with a potential for decreased serum levels and adverse events in the presence of inducers. The patient was eventually stabilized on a regimen of lithium, paliperidone, and quetiapine, avoiding oxcarbazepine. This case highlights the importance of considering individual patient factors, including pharmacogenetics when managing treatment-resistant patients. Monitoring serum clozapine levels and assessing enzyme activity before initiating therapy may help optimize treatment outcomes and minimize adverse events.

Early prediction and impact assessment of CYP3A4-related drug-drug interactions for small molecule anti-cancer drugs using human-CYP3A4-transgenic mouse models.

Early detection of drug-drug interactions (DDIs) can facilitate timely drug development decisions, prevent unnecessary restrictions on patient enrollment, resulting in clinical study populations that are not representative of the indicated study population, and allow for appropriate dose adjustments to ensure safety in clinical trials. All of these factors contribute to a streamlined drug approval process and enhanced patient safety. Here, we describe a new approach for early prediction of the magnitude of change in exposure for cytochrome P450 (CYP)3A4 related DDIs of small molecule anti-cancer drugs based on the model-based extrapolation of human-CYP3A4-transgenic mice pharmacokinetics to humans. Victim drugs brigatinib and lorlatinib were evaluated with the new approach in combination with the perpetrator drugs itraconazole and rifampicin. Predictions of the magnitude of change in exposure deviated at most 0.99 to 1.31 fold from clinical trial results for inhibition with itraconazole, while exposure predictions for the induction with rifampicin were less accurate with deviations of 0.22 to 0.48 fold. Results for the early prediction of DDIs and their clinical impact appear promising for CYP3A4 inhibition, but validation with more victim and perpetrator drugs is essential to evaluate the performance of the new method. Significance Statement The described method offers an alternative for the early detection and assessment of potential clinical impact of CYP3A4-related DDIs. The model was able to adequately describe the inhibition of CYP3A4 metabolism and the subsequent magnitude of change in exposure. However, it was unable to accurately predict the magnitude of change in exposure of victim drugs in combination with an inducer.

Effect of isavuconazole on the pharmacokinetics of sunitinib and its mechanism.

BACKGROUND: Sunitinib, a newly developed multi-targeted tyrosine kinase inhibitor (TKI), has become a common therapeutic option for managing advanced renal cell carcinoma (RCC). Examining the mechanism underlying the interaction between sunitinib and isavuconazole was the aim of this effort. METHODS: The concentrations of sunitinib and its primary metabolite, N-desethyl sunitinib, were analyzed and quantified using ultra performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS). Our study evaluated the potential interaction between isavuconazole and sunitinib using rat liver microsomes (RLM), human liver microsomes (HLM), and in vivo rat models. For the in vivo study, two groups (n = 5) of Sprague-Dawley (SD) rats were randomly allocated to receive sunitinib either with or without co-administration of isavuconazole. Additionally, the effects of isavuconazole on the metabolic stability of sunitinib and N-desethyl sunitinib were studied in RLM in vitro. RESULTS: Our findings demonstrated that in RLM, isavuconazole exhibited a mixed non-competitive and competitive inhibition mechanism, with an IC50 (half maximal inhibitory concentration) value of 1.33 µM. Meanwhile, in HLM, isavuconazole demonstrated a competitive inhibition mechanism, with an IC50 of 5.30 µM. In vivo studies showed that the presence of isavuconazole significantly increased the pharmacokinetic characteristics of sunitinib, with the AUC(0→t), AUC(0→∞), and Tmax rising to approximately 211.38%, 203.92%, and 288.89%, respectively, in contrast to the control group (5 mg/kg sunitinib alone). The pharmacokinetic characteristics of the metabolite N-desethyl sunitinib in the presence of isavuconazole remained largely unchanged compared to the control group. Furthermore, in vitro metabolic stability experiments revealed that isavuconazole inhibited the metabolic processing of both sunitinib and N-desethyl sunitinib. CONCLUSIONS: Isavuconazole had a major impact on sunitinib metabolism, providing fundamental information for the precise therapeutic administration of sunitinib.

Role of CYP2D6 and CYP3A4 polymorphisms on aripiprazole and dehydroaripiprazole concentrations in patients undergoing long-acting treatment.

Aripiprazole once-monthly (AOM) exhibits an important interindividual pharmacokinetic variability with significant implications for its clinical use. CYP2D6 and CYP3A4 highly contributes to this variability, as they metabolize aripiprazole (ARI) into its active metabolite, dehydroaripiprazole (DHA) and the latter into inactive metabolites. This study aims to evaluate the effect of CYP2D6 and CYP3A4 polymorphisms in combination and the presence of concomitant inducers and inhibitors of this cytochromes on ARI and DHA plasma concentrations in a real clinical setting. An observational study of a cohort of 74 Caucasian patients under AOM treatment was conducted. Regarding CYP2D6, higher concentrations were found for active moiety (ARI plus DHA) (AM) (67 %), ARI (67 %) and ARI/DHA ratio (77 %) for poor metabolizers (PMs) compared to normal metabolizers (NMs). No differences were found for DHA. PMs for both CYP2D6 and CYP3A4 showed a 58 % higher AM and 66 % higher plasma concentration for ARI compared with PMs for CYP2D6 and NMs for CYP3A4. In addition, PMs for both CYP2D6 and CYP3A4 have 45 % higher DHA concentrations than NMs for both cytochromes and 41 % more DHA than PMs for CYP2D6 and NMs for CYP3A4, suggesting a significant role of CYP3A4 in the elimination of DHA. Evaluating the effect of CYPD26 and CYP3A4 metabolizing state in combination on plasma concentrations of ARI, DHA and parent-to-metabolite ratio, considering concomitant treatments with inducers and inhibitor, could optimize therapy for patients under AOM treatment.

An in vitro evaluation on metabolism of mitragynine to 9-O-demethylmitragynine.

Kratom (Mitragyna Speciosa Korth.) is an indigenous tree native to Southeast Asia whose leaves have been traditionally ingested as a tea and has seen its popularity increase in the United States. Although kratom and its constituents presently have no approved uses by the Food and Drug Administration, its major alkaloids (e.g., mitragynine) have psychoactive properties that may hold promise for the treatment of opioid cessation, pain management, and other indications. 9-O-demethylmitragynine is a major metabolite formed from mitragynine metabolism (36 % total metabolism) and displays similar pharmacologic activity. Cytochrome P450 (CYP) 3A4 has been identified as a major enzyme involved in mitragynine metabolism; however, the in vitro metabolism parameters of 9-O-demethylmitragynine formation are not well defined and a risk of potential drug interactions exists. Using human liver S9 fractions, 9-O-demethylmitragynine formation was generally linear for enzyme concentrations of 0-0.25 mg/mL and incubation times of 5-20 min. 9-O-demethylmitragynine displayed a Km 1.37 µM and Vmax of 0.0931 nmol/min/mg protein. Known CYP inhibitors and compounds that might be concomitantly used with kratom were assessed for inhibition of 9-O-demethylmitragynine formation. Ketoconazole, a CYP3A index inhibitor, demonstrated a significant effect on 9-O-demethylmitragynine formation, further implicating CYP3A4 as a major metabolic pathway. Major cannabinoids (10 µg/mL) displayed minor inhibition of 9-O-demethylmitragynine formation, while all other compounds had minimal effects. Mixtures of physiological achievable cannabinoid concentrations also displayed minor effects on 9-O-demethylmitragynine formation, making a metabolic drug interaction unlikely; however, further in vitro, in vivo, and clinical studies are necessary to fully exclude any risk.

Concentration-dependent effects of the nerve agents cyclosarin and VX on cytochrome P450 in a HepaRG cell-based liver model.

The exposure to highly toxic organophosphorus (OP) compounds, including pesticides and nerve agents, is an ongoing medical challenge. OP can induce the uncontrolled overstimulation of the cholinergic system through inhibition of the enzyme acetylcholinesterase (AChE). The cytochrome P450 (CYP) enzymes in the liver play a predominant role in the metabolism of xenobiotics and are involved in the oxidative biotransformation of most clinical drugs. Previous research concerning the interactions between OP and CYP has usually focused on organothiophosphate pesticides that require CYP-mediated bioactivation to their active oxon metabolites to act as inhibitors of AChE. Since there has been little data available concerning the effect of nerve agents on CYP, we performed a study with cyclosarin (GF) and O-ethyl-S-[2-(diisopropylamino)-ethyl]-methylphosphonothioate (VX) by using a well-established, metabolically competent in vitro liver model (HepaRG cells). The inhibitory effect of the nerve agents GF and VX on the CYP3A4 enzyme was investigated showing a low CYP3A4 inhibitory potency. Changes on the transcription level of CYP and associated oxygenases were evaluated by quantitative reverse transcription polymerase chain reaction (qRT-PCR) using the two nerve agent concentrations 250 nM and 250 µM. In conclusion, the results demonstrated various effects on oxygenase-associated genes in dependence of the concentration and the structure of the nerve agent. Such information might be of relevance for potential interactions between nerve agents, antidotes or other clinically administered drugs, which are metabolized by the affected CYP, for example, for the therapy with benzodiazepines, that are used for the symptomatic treatment of OP poisoning and that require CYP-mediated biotransformation.

Concomitant Administration of Psychotropic and Prostate Cancer Drugs: A Pharmacoepidemiologic Study Using Drug-Drug Interaction Databases.

Prostate cancer (PC) represents the second most common diagnosed cancer in men. The burden of diagnosis and long-term treatment may frequently cause psychiatric disorders in patients, particularly depression. The most common PC treatment option is androgen deprivation therapy (ADT), which may be associated with taxane chemotherapy. In patients with both PC and psychiatric disorders, polypharmacy is frequently present, which increases the risk of drug-drug interactions (DDIs) and drug-related adverse effects. Therefore, this study aimed to conduct a pharmacoepidemiologic study of the concomitant administration of PC drugs and psychotropics using three drug interaction databases (Lexicomp®, drugs.com®, and Medscape®). This study assayed 4320 drug-drug combinations (DDCs) and identified 814 DDIs, out of which 405 (49.63%) were pharmacokinetic (PK) interactions and 411 (50.37%) were pharmacodynamic (PD) interactions. The most common PK interactions were based on CYP3A4 induction (n = 275, 67.90%), while the most common PD interactions were based on additive torsadogenicity (n = 391, 95.13%). Proposed measures for managing the identified DDIs included dose adjustments, drug substitutions, supplementary agents, parameters monitoring, or simply the avoidance of a given DDC. A significant heterogenicity was observed between the selected drug interaction databases, which can be mitigated by cross-referencing multiple databases in clinical practice.

Mitigating CYP3A4-mediated aflatoxin toxicity with algal-derived Sodium Copper Chlorophyllin: Production and In-silico insights.

The present research explores the cytotoxic mechanism of protein Cytochrome P450 (CYP3A4) with aflatoxin (AFB1), a potent carcinogen. Cytochrome P450 is an essential enzyme involved in drug metabolism, however epoxide formation due to the binding event of AFB1 leads to cell cytotoxicity. In this direction, our study elucidates the scavenging effect of algal-derived Sodium Copper Chlorophyllin (SCC) over AFB1 cytotoxicity. Cyanobacteria/ microalgae-derived SCC have garnered attention due to its diverse applications in pharmacological and food industries. This work began with the production of SCC from Spirulina and Chlorella sp. over a stipulated period of growth. Subsequently, the study delved into the interplay between SCC and the carcinogenic impact of AFB1 on the CYP3A4 enzyme. Computational studies demonstrated SCC binding and blocking mechanisms against AFB1. Our research intended to determine whether CYP3A4 can bind to SCC that, in turn, act as an interceptor for AFB1 or influence the metabolism of bound AFB1. Current results support that SCC is an effective AFB1 trap as it shows interactions with AFB1. These findings would open up new avenues in clinical biology/pharmacology to further explore the mechanisms of action of CYP3A4 with AFB1 and SCC, offering promising prospects for abating cell cytotoxicity.

The effect of gene polymorphism on ticagrelor metabolism: an in vitro study of 22 CYP3A4 variants in Chinese Han population.

Background: Ticagrelor is a novel oral antiplatelet agent which can selectively inhibit P2Y12 receptor. Bleeding and dyspnea are common adverse reactions of ticagrelor in clinic. The side effects of ticagrelor are correlated with the plasma concentration of ticagrelor. Objective: This study aimed to evaluate the catalytic characteristics of 22 CYP3A4 alleles identified in the Chinese Han population on the metabolism of ticagrelor in vitro, focusing on the effect of CYP3A4 polymorphism on ticagrelor metabolism. Methods: In this study, insect cells were used to express 22 CYP3A4 variants, which were then incubated with 1-50 µM ticagrelor at 37 °C for 30 minutes to obtain the metabolite (AR-C124910XX). AR-C124910XX was detected by UHPLC-MS/MS to calculate the kinetic parameters, including Km, Vmax and CLint. Results: Compared to the wild-type, most CYP3A4 alleles exhibited significant differences in intrinsic clearance. The intrinsic clearance of CYP3A4*11, *18 and *33 was much higher than that of wild-type; four variants exhibited similar intrinsic clearance values as the wild-type enzyme; The remaining 14 variants showed significantly reduced intrinsic clearance values, ranging from 1.48% to 75.11% of the wild-type; CYP3A4*30 displayed weak or no activity. Conclusion: This study conducted a comprehensive assessment of the effect of CYP3A4 variants on ticagrelor's metabolism. The results suggested that there is allele-specific activity towards ticagrelor in vitro. These findings can provide some insights and predictions for treatment strategies and risk assessments associated with ticagrelor in clinical practice.

Distribution of CYP3A4 and CYP3A5 Polymorphisms and Genotype Combination Implicated in Tacrolimus Metabolism.

INTRODUCTION: Human cytochrome P450 (CYP), particularly CYP3A4 and CYP3A5 is mainly responsible for the metabolism of several drugs including tacrolimus. Significant interracial/interethnic variation in the expression and function of CYP3A5 and CYP3A4 is caused by Single Nucleotide Polymorphisms (SNPs) of genes encoding these proteins. AIM: The present study investigated the genetic polymorphisms CYP3A4*1B, CYP3A4*22, and CYP3A5*3 in the Tunisian population. METHODS: We included in this study, Tunisian healthy subjects and renal transplant recipients receiving tacrolimus. CYP3A4 and CYP3A5 genotyping were performed using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). According to the genotypic combination of the three CYP polymorphisms, we have identified for the first time four metabolizers statuses: slow metabolizers (SM), intermediate metabolizers (IM), high metabolizers (HM), and extensive metabolizers (EM). RESULTS: A total of 101 renal transplant patients and 102 healthy subjects were included. Our results showed that the predominant alleles in the Tunisian population are a wild type of CYP3A4*1B (0.87), likewise CYP3A4*22 (0.975) and CYP3A5*3 (0.82). The genotype frequencies of CYP3A4*1B, CYP3A4*22, and CYP3A5*3 were found to be 3.9%, 0.0%, and 69.5%, respectively. Also, we found a significant linkage disequilibrium between CYP3A4*1B and CYP3A5*3. We approved that the IM is the predominant phenotype in our population with 124 patients followed by and EM with 41 patients, HM in 29 patients and SM in 9 patients. These results showed that Tunisians are most similar to Caucasians. CONCLUSION: The genetic background of these enzymes CYP3A4*1B, CYP3A4*22, and CYP3A5*3 in this study are important in the prescription of personalized medicine.

Metabolic disrupting chemicals in the intestine: the need for biologically relevant models: Zebrafish: what can we learn from this small environment-sensitive fish?

Although the concept of endocrine disruptors first appeared almost 30 years ago, the relatively recent involvement of these substances in the etiology of metabolic pathologies (obesity, diabetes, hepatic steatosis, etc.) has given rise to the concept of Metabolic Disrupting Chemicals (MDCs). Organs such as the liver and adipose tissue have been well studied in the context of metabolic disruption by these substances. The intestine, however, has been relatively unexplored despite its close link with these organs. In vivo models are useful for the study of the effects of MDCs in the intestine and, in addition, allow investigations into interactions with the rest of the organism. In the latter respect, the zebrafish is an animal model which is used increasingly for the characterization of endocrine disruptors and its use as a model for assessing effects on the intestine will, no doubt, expand. This review aims to highlight the importance of the intestine in metabolism and present the zebrafish as a relevant alternative model for investigating the effect of pollutants in the intestine by focusing, in particular, on cytochrome P450 3A (CYP3A), one of the major molecular players in endogenous and MDCs metabolism in the gut.

Effect of protein binding on the pharmacokinetics of the six substrates in the Basel phenotyping cocktail in healthy subjects and patients with liver cirrhosis.

Phenotyping serves to estimate enzyme activities in healthy persons and patients in vivo. Low doses of enzyme-specific substrates are administered, and activities estimated using metabolic ratios (MR, calculated as AUCmetabolite/AUCparent). We administered the Basel phenotyping cocktail containing caffeine (CYP1A2 substrate), efavirenz (CYP2B6), flurbiprofen (CYP2C9), omeprazole (CYP2C19), metoprolol (CYP2D6) and midazolam (CYP3A) to 36 patients with liver cirrhosis and 12 control subjects and determined free and total plasma concentrations over 24 h. Aims were to assess whether MRs reflect CYP activities in patients with liver cirrhosis and whether MRs calculated with free plasma concentrations (MRfree) provide better estimates than with total concentrations (MRtotal). The correlation of MRtotal with MRfree was excellent (R2 >0.910) for substrates with low (<30 %, caffeine and metoprolol) and intermediate protein binding (≥30 and <99 %, midazolam and omeprazole) but weak (R2 <0.30) for substrates with high protein binding (≥99 %, efavirenz and flurbiprofen). The correlations between MRtotal and MRfree with CYP activities were good (R2 >0.820) for CYP1A2, CYP2C19 and CYP2D6. CYP3A4 activity was reflected better by midazolam elimination than by midazolam MRtotal or MRfree. The correlation between MRtotal and MRfree with CYP activity was not significant or weak for CYP2B6 and CYP2C9. In conclusion, MRs of substrates with an extensive protein binding (>99 %) show high inter-patient variabilities and do not accurately reflect CYP activity in patients with liver cirrhosis. Protein binding of the probe drugs has a high impact on the precision of CYP activity estimates and probe drugs with low or intermediate protein binding should be preferred.

Assessing the impact of aprepitant on response to dose-intensive cyclophosphamide, etoposide, and cisplatin (DICEP).

BACKGROUND: Despite evidence demonstrating the effectiveness of aprepitant for chemotherapy-induced nausea and vomiting (CINV), its use in stem cell transplant settings across Canada is not standard. While pharmacokinetic data exists, the clinical significance of cytochrome P450 3A4 (CYP 3A4) inhibition of cyclophosphamide by aprepitant is unclear. Reduced activation of cyclophosphamide may reduce the effectiveness of dose-intensive cyclophosphamide, etoposide, and cisplatin (DICEP). OBJECTIVES: To compare response rates to DICEP in patients with Hodgkin lymphoma (HL) and diffuse large B-cell lymphoma (DLBCL) in the presence and absence of aprepitant. METHODS: A retrospective review of patients who received full-dose DICEP for relapsed/refractory HL or DLBCL between June 1995 and September 2018 at the Foothills Medical Centre (FMC) in Calgary, Alberta, Canada was conducted. Descriptive statistics were used to assess response rate, as defined by the 2007 International Working Group response criteria. RESULTS: Of the 218 patients included in this study, 87.6% of patients in the control group and 88.5% of patients in the aprepitant group responded to DICEP (difference 0.025 [95% CI, -0.066 to 0.114], p = 0.827). Univariate analyses for age, sex, type of cancer, stage of cancer, number of prior relapses, and relapse status were not significant. No significant differences were observed for secondary outcomes. CONCLUSION: Response rates to DICEP in relapsed/refractory HL and DLBCL patients were similar regardless of aprepitant use. Considering these results and the effectiveness of aprepitant in CINV, its addition to standard antiemetic therapy in patients receiving DICEP should be given strong consideration in the transplant setting.

Drug-induced enzyme activity inhibition and CYP3A4 genetic polymorphism significantly shape the metabolic characteristics of furmonertinib.

This study aimed to elucidate the impact of variations in liver enzyme activity, particularly CYP3A4, on the metabolism of furmonertinib. An in vitro enzyme incubation system was established for furmonertinib using liver microsomes and recombinant CYP3A4 baculosomes, with analytes detected by LC-MS/MS. The pharmacokinetic characteristics of furmonertinib were studied in vivo using Sprague-Dawley rats. It was found that telmisartan significantly inhibited the metabolism of furmonertinib, as demonstrated by a significant increase in the AUC of furmonertinib when co-administered with telmisartan, compared to the furmonertinib-alone group. Mechanistically, it was noncompetitive in rat liver microsomes, while it was mixed competitive and noncompetitive in human liver microsomes and CYP3A4. Considering the genetic polymorphism of CYP3A4, the study further investigated its effect on the kinetics of furmonertinib. The results showed that compared to CYP3A4.1, CYP3A4.29 had significantly increased activity in catalyzing furmonertinib, whereas CYP3A4.7, 9, 10, 12, 13, 14, 18, 23, 33, and 34 showed markedly decreased activity. The inhibitory activity of telmisartan varied in CYP3A4.1 and CYP3A4.18, with IC50 values of 8.56 ± 0.90 µM and 27.48 ± 3.52 µM, respectively. The key loci affecting the inhibitory effect were identified as ARG105, ILE301, ALA370, and LEU373. Collectively, these data would provide a reference for the quantitative application of furmonertinib.

Characteristics of CYP3A4-related potential drug-drug interactions in outpatients receiving prescriptions from multiple clinical departments.

BACKGROUND: Drug-drug interactions (DDIs) increase the incidence of adverse drug reactions (ADRs). In a previous report, we revealed that the incidence of potential DDIs due to the same CYP molecular species in one prescription exceeds 90% among patients taking six or more drugs and that CYP3A4 markedly influences the increase in the number of potential DDIs in clinical practice. However, the factors contributing to an increased number of potential DDIs in prescriptions from multiple clinical departments remain poorly clarified. METHODS: This observational study was performed at five pharmacies in Okayama Prefecture, Japan. Patients who visited these pharmacies from 11 April 2022 to 24 April 2022 were included, except those who had prescriptions only from a single clinical department. A stratified analysis was performed to determine the incidence of CYP3A4-related potential DDIs according to the number of drugs taken. Additionally, factors associated with an increase in the number of drugs involved in CYP3A4-related potential DDIs were identified using multiple linear regression analysis. In this study, potential DDIs for the prescription data subdivided by clinical department, containing two or more drugs, were used as control data. RESULTS: Overall, 372 outpatients who received prescriptions from multiple clinical departments were included in the current study. The number of drugs contributing to CYP3A4-related potential DDIs increased with an increase in the number of clinical departments. Notably, in cases taking fewer than six drugs, prescriptions from multiple clinical departments had a higher frequency of CYP3A4-related potential DDIs than those in prescriptions subdivided by clinical department. Multiple regression analysis identified "Cardiovascular agents", "Agents affecting central nervous system", and "Urogenital and anal organ agents" as the top three drug classes that increase CYP3A4-related potential DDIs. CONCLUSION: Collectively, these results highlight the importance of a unified management strategy for prescribed drugs and continuous monitoring of ADRs in outpatients receiving prescriptions from multiple clinical departments even if the number of drugs taken is less than six.

Identification of reversible OATP1B1 and time-dependent CYP3A4 inhibition as the major risk factors for drug-induced cholestasis (DIC).

Hepatic bile acid regulation is a multifaceted process modulated by several hepatic transporters and enzymes. Drug-induced cholestasis (DIC), a main type of drug-induced liver injury (DILI), denotes any drug-mediated condition in which hepatic bile flow is impaired. Our ability in translating preclinical toxicological findings to human DIC risk is currently very limited, mainly due to important interspecies differences. Accordingly, the anticipation of clinical DIC with available in vitro or in silico models is also challenging, due to the complexity of the bile acid homeostasis. Herein, we assessed the in vitro inhibition potential of 47 marketed drugs with various degrees of reported DILI severity towards all metabolic and transport mechanisms currently known to be involved in the hepatic regulation of bile acids. The reported DILI concern and/or cholestatic annotation correlated with the number of investigated processes being inhibited. Furthermore, we employed univariate and multivariate statistical methods to determine the important processes for DILI discrimination. We identified time-dependent inhibition (TDI) of cytochrome P450 (CYP) 3A4 and reversible inhibition of the organic anion transporting polypeptide (OATP) 1B1 as the major risk factors for DIC among the tested mechanisms related to bile acid transport and metabolism. These results were consistent across multiple statistical methods and DILI classification systems applied in our dataset. We anticipate that our assessment of the two most important processes in the development of cholestasis will enable a risk assessment for DIC to be efficiently integrated into the preclinical development process.

Iminium ion metabolites are formed from nintedanib by human CYP3A4.

Nintedanib is used to treat idiopathic pulmonary fibrosis, systemic sclerosis, interstitial lung disease, and progressive fibrotic interstitial lung disease. It is primarily cleared via hepatic metabolism, hydrolysis, and glucuronidation. In addition, formation of the iminium ion, a possible reactive metabolite, was predicted based on the chemical structure of nintedanib. To obtain a hint which may help to clarify the cause of nintedanib-induced liver injury, we investigated whether iminium ions were formed in the human liver. To detect unstable iminium ions using liquid chromatography-tandem mass spectrometry (LC-MS/MS), potassium cyanide was added to the reaction mixture as a trapping agent. Human liver and intestinal microsomes were incubated with nintedanib in the presence of NADPH to form two iminium ion metabolites on the piperazine ring. Their formation is strongly inhibited by ketoconazole, a potent cytochrome P450 (CYP) 3A4 inhibitor. Among the recombinant P450s, only CYP3A4 formed cyanide adducts. The role of CYP3A4 was supported by the positive correlation between CYP3A4 protein abundance, as determined by LC-MS-based proteomics, and the formation of cyanide adducts in 25 individual human liver microsomes. In conclusion, we have demonstrated that iminium ion metabolites are formed from nintedanib by CYP3A4 as potential reactive metabolites.

Genetic variation present in the CYP3A4 gene in Ni-Vanuatu and Kenyan populations in malaria endemicity.

Cytochrome P450 3A4 (CYP3A4) enzyme is involved in the metabolism of about 30 % of clinically used drugs, including the antimalarials artemether and lumefantrine. CYP3A4 polymorphisms yield enzymatic variants that contribute to inter-individual variation in drug metabolism. Here, we examined CYP3A4 polymorphisms in populations from malaria-endemic islands in Lake Victoria, Kenya, and Vanuatu, to expand on the limited data sets. We used archived dried blood spots collected from 142 Kenyan and 263 ni-Vanuatu adults during cross-sectional malaria surveys in 2013 and 2005-13, respectively, to detect CYP3A4 variation by polymerase chain reaction (PCR) and sequencing. In Kenya, we identified 14 CYP3A4 single nucleotide polymorphisms (SNPs), including the 4713G (CYP3A4∗1B; allele frequency 83.9 %) and 19382A (CYP3A4∗15; 0.7 %) variants that were previously linked to altered metabolism of antimalarials. In Vanuatu, we detected 15 SNPs, including the 4713A (CYP3A4∗1A; 88.6 %) and 25183C (CYP3A4∗18; 0.6 %) variants. Additionally, we detected a rare and novel SNP C4614T (0.8 %) in the 5' untranslated region. A higher proportion of CYP3A4 genetic variance was found among ni-Vanuatu populations (16 %) than among Lake Victoria Kenyan populations (8 %). Our work augments the scarce data sets and contributes to improved precision medicine approaches, particularly to anti-malarial chemotherapy, in East African and Pacific Islander populations.