Cytochrome P450 3A4 Substrate Research Articles

Value of Assessing 1-Hydroxymidazolam in Drug-Drug Interaction Studies with Midazolam as a Substrate of Cytochrome P450 3A.

The purpose of this overview was to perform an exploratory analysis of in-house drug-drug interaction (DDI) studies conducted with investigational drugs and oral midazolam to assess the value of measuring 1-OH-midazolam (1-OHM) in such studies. The perpetrator effect of the investigational drugs on cytochrome P450 3A (CYP3A) was assessed by analyzing both midazolam and 1-OHM in plasma and evaluating their pharmacokinetic parameters. Given the almost exclusive metabolism of the parent drug by CYP3A to the main metabolite 1-OHM, an increase in midazolam and a decrease in 1-OHM exposure in the case of CYP3A inhibition caused by a perpetrator drug would be expected. The opposite would be anticipated in the case of CYP3A induction. For this analysis, the perpetrator potential of eight different investigational drugs was incorporated. Among the 10 studies included, the identified CYP3A inhibitors (n = 4) and inducers (n = 1) were classified based on the data generated with midazolam per se, with 1-OHM levels not contributing to the interpretation of the data as they did not corroborate the findings of the parent compound. Therefore, it was concluded that continued analysis of 1-OHM in plasma may be questionable as it does not add value to the interpretation of the results when performing CYP3A DDI studies with an investigational drug as a perpetrator.

A physiologically-based pharmacokinetic precision dosing approach to manage dasatinib drug-drug interactions.

Dasatinib, a second-generation tyrosine kinase inhibitor, is approved for treating chronic myeloid and acute lymphoblastic leukemia. As a sensitive cytochrome P450 (CYP) 3A4 substrate and weak base with strong pH-sensitive solubility, dasatinib is susceptible to enzyme-mediated drug-drug interactions (DDIs) with CYP3A4 perpetrators and pH-dependent DDIs with acid-reducing agents. This work aimed to develop a whole-body physiologically-based pharmacokinetic (PBPK) model of dasatinib to describe and predict enzyme-mediated and pH-dependent DDIs, to evaluate the impact of strong and moderate CYP3A4 inhibitors and inducers on dasatinib exposure and to support optimized dasatinib dosing. Overall, 63 plasma profiles from perorally administered dasatinib in healthy volunteers and cancer patients were used for model development. The model accurately described and predicted plasma profiles with geometric mean fold errors (GMFEs) for area under the concentration-time curve from the first to the last timepoint of measurement (AUClast) and maximum plasma concentration (Cmax) of 1.27 and 1.29, respectively. Regarding the DDI studies used for model development, all (8/8) predicted AUClast and Cmax ratios were within twofold of observed ratios. Application of the PBPK model for dose adaptations within various DDIs revealed dasatinib dose reductions of 50%-80% for strong and 0%-70% for moderate CYP3A4 inhibitors and a 2.3-3.1-fold increase of the daily dasatinib dose for CYP3A4 inducers to match the exposure of dasatinib administered alone. The developed model can be further employed to personalize dasatinib therapy, thereby help coping with clinical challenges resulting from DDIs and patient-related factors, such as elevated gastric pH.

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

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

Pharmacokinetic study of capivasertib and the CYP3A4 substrate midazolam in patients with advanced solid tumors.

Capivasertib, a potent, selective inhibitor of all three AKT serine/threonine kinase (AKT) isoforms, is being evaluated in phase 3 trials in advanced breast and prostate cancer. This study evaluated the drug-drug interaction risk of capivasertib with the cytochrome P450 3A substrate midazolam in previously treated adults with advanced solid tumors. Patients received oral capivasertib 400mg twice daily (BID) on an intermittent schedule (4days on/3days off) starting on day 2 of cycle 1 (29days) and on day 1 of each 28-day cycle thereafter. In cycle 1 only, patients received oral midazolam (1mg) on day 1 (alone), and days 8 and 12 (3rd day off and 4th day on capivasertib, respectively). Midazolam pharmacokinetics on days 8 and 12 were analyzed versus day 1. Capivasertib, with or without standard-of-care treatment, was continued in patients deemed likely to benefit. Safety and exploratory efficacy analyses were conducted. Capivasertib-midazolam coadministration increased midazolam exposure (n = 21): geometric mean ratio (90% confidence interval) AUCinf and Cmax was 1.13 (0.97-1.32) and 1.15 (0.99-1.33) for day 8 versus day 1, and 1.75 (1.50-2.05) and 1.25 (1.08-1.46) for day 12 versus day 1. The capivasertib safety profile was manageable when administered with or without midazolam. Two patients had partial responses to treatment. The up to 1.75-fold increase in midazolam exposure indicates capivasertib is a weak CYP3A inhibitor at 400mg BID on an intermittent schedule. Capivasertib was well tolerated; exploratory efficacy analysis demonstrated evidence of clinical activity in this heavily pre-treated population. gov: NCT04958226.

Physiologically based pharmacokinetic modeling to predict the clinical effect of azole antifungal agents as CYP3A inhibitors on azelnidipine pharmacokinetics

In this study, a physiologically based pharmacokinetic (PBPK) model of the cytochrome P450 3A (CYP3A) substrate azelnidipine was developed using in vitro and clinical data to predict the effects of azole antifungals on azelnidipine pharmacokinetics. Modeling and simulations were conducted using the Simcyp™ PBPK simulator. The azelnidipine model consisted of a full PBPK model and a first-order absorption model. CYP3A was assumed as the only azelnidipine elimination route, and CYP3A clearance was optimized using the pharmacokinetic profile of single-dose 5-mg azelnidipine in healthy participants. The model reproduced the results of a clinical drug–drug interaction study and met validation criteria. PBPK model simulations using azole antifungals (itraconazole, voriconazole, posaconazole, fluconazole, fosfluconazole) and azelnidipine or midazolam (CYP3A index substrate) were performed. Increases in the simulated area under the plasma concentration–time curve from time zero extrapolated to infinity with inhibitors were comparable between azelnidipine (range, 2.11–6.47) and midazolam (range, 2.26–9.22), demonstrating that azelnidipine is a sensitive CYP3A substrate. Increased azelnidipine plasma concentrations are expected when co-administered with azole antifungals, potentially affecting azelnidipine safety. These findings support the avoidance of azole antifungals in patients taking azelnidipine and demonstrate the utility of PBPK modeling to inform appropriate drug use.

Quantitative analysis of the impact of membrane permeability on intestinal first-pass metabolism of CYP3A substrates.

The aim of this study was firstly to investigate the effect of membrane permeability on the intestinal availability (Fg ) of 10 cytochrome P450 3A4 substrates with differing permeability (Papp ) and metabolic activity (CLint ) using Madin-Darby canine kidney II (MDCKII) cells expressing human CYP3A4 (MDCKII/CYP3A4 cells), and secondly to confirm the essential factors by simulations. A membrane permeation assay using MDCKII/CYP3A4 cells showed a significant correlation between human intestinal extraction ratio (ER) (Eg (=1-Fg )) and in vitro cellular ER (r=0.834). This relationship afforded better predictability of Eg values than the relationship between Eg and CLint,HIM values obtained from human intestinal microsomes (r=0.598). An even stronger correlation was observed between 1-Fa ·Fg and ER (r=0.874). Simulation with a cellular kinetic model indicated that ER is sensitive to changes of PSpassive and CLint values, but not to the intracellular unbound fraction (fu,cell ) or P-gp-mediated efflux (PSP-gp ). It may be concluded that, based on the concentration-time profile of drugs in epithelial cells, transmembrane permeability influences Fg (or ER) and drug exposure time to metabolizing enzymes for P450 substrate.

Assessment of CYP3A-mediated drug interaction via cytokine (IL-6) elevation for mosunetuzumab using physiologically-based pharmacokinetic modeling.

Mosunetuzumab is a CD3/CD20 bispecific antibody. As an on-target effect, transient elevation of interleukin-6 (IL-6) occurs in early treatment cycles. A physiologically-based pharmacokinetic (PBPK) model was developed to assess potential drug interaction caused by IL-6 enzyme suppression on cytochrome P450 3A (CYP3A) during mosunetuzumab treatment. The model's performance in predicting IL-6 CYP3A suppression and subsequent drug-drug interactions (DDIs) was verified using existing clinical data of DDIs caused by chronic and transient IL-6 elevation. Sensitivity analyses were performed for a complete DDI risk assessment. The IL-6 concentration- and time-dependent CYP3A suppression during mosunetuzumab treatment was simulated using PBPK model with incorporation of invitro IL-6 inhibition data. At clinically approved doses/regimens, the DDI at maximum CYP3A suppression was predicted to be a midazolam maximum drug concentration in plasma (Cmax ) and area under the plasma drug concentration-time curve (AUC) ratio of 1.17 and 1.37, respectively. At the 95th percentile of IL-6 concentration level or when gut CYP3A suppression was considered, the predicted DDI risk for mosunetuzumab remained low (<2-fold). The PBPK-based DDI predictions informed the mosunetuzumab product label to monitor, in early cycles, the concentrations and toxicities for sensitive CYP3A substrates with narrow therapeutic windows.

Physiologically Based Pharmacokinetic Modeling of the Drug-Drug Interaction Between CYP3A4 Substrate Glasdegib and Moderate CYP3A4 Inducers in Lieu of a Clinical Study.

Glasdegib (DAURISMO) is a hedgehog pathway inhibitor approved for the treatment of acute myeloid leukemia (AML). Cytochrome P450 3A4 (CYP3A4) has been identified as a major metabolism and clearance pathway for glasdegib. The role of CYP3A4 in the clearance of glasdegib has been confirmed with clinical drug-drug interaction (DDI) studies following the coadministration of glasdegib with the strong CYP3A4 inhibitor ketoconazole and the strong inducer rifampin. To evaluate potential drug interactions with CYP3A4 modulators, the coadministration of glasdegib with a moderate CYP3A4 inducer, efavirenz, was evaluated using physiologically based pharmacokinetic (PBPK) modeling using the Simcyp simulator. The glasdegib compound file was developed using measured physicochemical properties, data from human intravenous and oral pharmacokinetics, absorption, distribution, metabolism, and excretion studies, and invitro reaction phenotyping results. The modeling assumptions, model parameters, and assignments of fractional CYP3A4 metabolism were verified using results from clinical pharmacokinetics (PK) and DDI studies with ketoconazole and rifampin. The verified glasdegib and efavirenz compound files, the latter of which was available in the Simcyp simulator, were used to estimate the potential impact of efavirenz on the PK of glasdegib. PBPK modeling predicted a glasdegib area under the concentration-time curve ratio of 0.45 and maximum plasma concentration ratio of 0.75 following coadministration with efavirenz. The PBPK results, in lieu of a formal clinical study, informed the drug label, with the recommendation to double the clinical dose of glasdegib when administered in conjunction with a moderate CYP3A4 inducer, followed by a resumption of the original dose 7days post-discontinuation.

Development and Verification of a Japanese Pediatric Physiologically Based Pharmacokinetic Model with Emphasis on Drugs Eliminated by Cytochrome P450 or Renal Excretion.

Physiologically based pharmacokinetic (PBPK) models are useful in bridging drug exposure in different ethnic groups, and there is increasing regulatory application of this approach in adults. Reported pediatric PBPK models tend to focus on the North European population, with few examples in other ethnic groups. This study describes the development and verification of a Japanese pediatric PBPK population. The development of the model was based on the existing North European pediatric population. Japanese systems and clinical data were collated from public databases and the literature, and the underlying demographics and equations were optimized so that physiological outputs represented the Japanese pediatric population. The model was tested using 14 different small molecule drugs, eliminated by a variety of pathways, including cytochrome P450 3A4 (CYP3A4) metabolism and renal excretion. Given the limitations of the clinical data, the overall performance of the model was good, with 44/62 predictions for PK parameters (area under the plasma drug concentration-time curve, AUC; maximum serum concentration, Cmax ; clearance, CL) being within 0.8- to 1.25-fold, 56/62 within 0.67- to 1.5-fold, and 61/62 within 0.5- to 2.0-fold of the observed values. Specific results for the 5 CYP3A4 substrates showed 20/31 cases were predicted within 0.8- to 1.25-fold, 27/31 within 0.67- to 1.5-fold, and all were within 0.5- to 2.0-fold of the observed values. Given the increased regulatory use of pediatric PBPK in drug development, expanding these models to other ethnic groups are important. Considering qualifying these models based on the context of use, there is a need to expand on the current research to include a larger range of drugs with different elimination pathways. Collaboration among academic, industry, model providers, and regulators will facilitate further development.

Impact of Heterotropic Allosteric Modulation on the Time-Dependent Inhibition of Cytochrome P450 3A4.

The current study was designed to investigate the influence of allosteric effectors on the metabolism of the prototypical cytochrome P450 (CYP) 3A4 substrate midazolam (MDZ), and on the determination in vitro time-dependent inhibition (TDI) of CYP3A4 using human liver microsomes (HLM). As the concentration of midazolam increased to 250 µM in HLMs, homotropic cooperativity resulted in a decrease in the 1'-hydroxymidazolam to 4-hydroxymidazolam ratio to a maximum of 1.1. The presence of varying concentrations of testosterone, progesterone (PGS), or carbamazepine (CBZ) in HLMs with MDZ could recapitulate the effect of homotropic cooperativity such that the formation rates of the 1'hydroxymidazolam and 4-hydroxymidazolam were equal even at low concentrations of MDZ. The presence of PGS (10 or 100 µM) and CBZ (100 or 1000 µM) in in vitro TDI determination of four known CYP3A4 time-dependent inactivators (clarithromycin, troleandomycin, mibefradil, raloxifene) simultaneously decreased potency and inactivation rate constant, resulting in fold changes in inactivation efficiency on average of 1.6-fold and 13-fold for the low and high concentrations of allosteric modulator tested, respectively. The formation of a metabolic-intermediate complex (MIC) for clarithromycin and troleandomycin decreased in the presence of the allosteric modulators in a concentration-dependent manner, reaching a new steady state formation that could not be overcome with increased incubation time. Maximum reduction of the MIC formed by clarithromycin was up to ∼91%, while troleandomycin MIC decreased up to ∼31%. These findings suggest that the absence of endogenous allosteric modulators may contribute to the poor translation of HLM-based drug-drug interaction predictions. SIGNIFICANCE STATEMENT: The reported overprediction of in vitro human liver microsome time-dependent inhibition of CYP3A4 and observed drug interactions in vivo remains an issue in drug development. We provide characterization of allosteric modulators on the CYP3A4 metabolism of the prototypical substrate midazolam, demonstrating the ability of the modulators to recapitulate the homotropic cooperativity of midazolam. Furthermore, we demonstrate that allosteric heterotropic cooperativity of CYP3A4 can impact the time-dependent inhibition kinetics of known mechanisms-based inhibitors, providing a potential mechanism to explain the overprediction.

Interaction of CYP3A4 with caffeine: First insights into multiple substrate binding

Human cytochrome P450 3A4 (CYP3A4) is a major drug-metabolizing enzyme that shows extreme substrate promiscuity. Moreover, its large and malleable active site can simultaneously accommodate several substrate molecules of the same or different nature, which may lead to cooperative binding and allosteric behavior. Due to difficulty of crystallization of CYP3A4-substrate complexes, it remains unknown how multiple substrates can arrange in the active site. We determined crystal structures of CYP3A4 bound to three and six molecules of caffeine, a psychoactive alkaloid serving as a substrate and modulator of CYP3A4. In the ternary complex, one caffeine binds to the active site suitably for C8-hydroxylation, most preferable for CYP3A4. In the senary complex, three caffeine molecules stack parallel to the heme with the proximal ligand poised for 3-N-demethylation. However, the caffeine stack forms extensive hydrophobic interactions that could preclude product dissociation and multiple turnovers. In both complexes, caffeine is also bound in the substrate channel and on the outer surface known as a peripheral site. At all sites, aromatic stacking with the caffeine ring(s) is likely a dominant interaction, while direct and water-mediated polar contacts provide additional stabilization for the substrate-bound complexes. Protein-ligand interactions via the active site R212, intrachannel T224, and peripheral F219 were experimentally confirmed, and the latter two residues were identified as important for caffeine association. Collectively, the structural, spectral, and mutagenesis data provide valuable insights on the ligand binding mechanism and help better understand how purine-based pharmaceuticals and other aromatic compounds could interact with CYP3A4 and mediate drug-drug interactions.

A Promising Approach to Treat Psoriasis: Inhibiting Cytochrome P450 3A4 Metabolism to Enhance Desoximetasone Therapy.

(1) Background: Human keratinocytes and murine skin express various cytochrome P450 enzymes. These include cytochrome P450 3A4, which may participate in the metabolism of cytochrome P450 3A4 substrate drugs. Desoximetasone, a topical corticosteroid and cytochrome P450 3A4 substrate, is used to treat skin conditions such as skin allergies, atopic dermatitis, and psoriasis. In this study, we aimed to investigate the anti-psoriatic effect of a low dose of desoximetasone by inhibiting cytochrome P450 3A4 metabolism in the epidermis. (2) Methods: Psoriasis-like skin was induced in BALB/c mice via the topical administration of imiquimod. The mice were then topically treated with 0.01-0.05% desoximetasone loaded into a cytochrome P450 3A4 enzyme inhibitor excipient base emollient microemulsion, 0.25% commercial desoximetasone ointment, or 0.5 mg/gm clobetasol ointment. (3) Results: The topical application of 0.05% desoximetasone loaded into a cytochrome P450 3A4 enzyme inhibitor excipient base emollient formulation restored the imiquimod-induced skin barrier disruption and resulted in fewer severe clinical and pathological features compared with the treatments with 0.25% commercial desoximetasone ointment and 0.5 mg/gm clobetasol ointment. (4) Conclusions: The cytochrome P450 3A4 enzyme inhibitor excipient base emollient formulation improved and prolonged the therapeutic effect of cytochrome P450 3A4 substrate drugs and may be a promising approach for psoriasis treatment.

Effects of nirmatrelvir/ritonavir on midazolam and dabigatran pharmacokinetics in healthy participants.

To evaluate pharmacokinetics (PK) and safety after coadministration of nirmatrelvir/ritonavir or ritonavir alone with midazolam (a cytochrome P450 3A4 substrate) and dabigatran (a P-glycoprotein substrate). PK was studied in 2 phase 1, open-label, fixed-sequence studies in healthy adults. Single oral doses of midazolam 2 mg (n= 12) or dabigatran 75 mg (n= 24) were administered alone and after steady state (i.e. ≥2 days) of nirmatrelvir/ritonavir 300 mg/100 mg and ritonavir 100 mg. Midazolam and dabigatran plasma concentrations and adverse events were analysed for each treatment. After administration of midazolam with nirmatrelvir/ritonavir (test) or alone (reference), midazolam geometric mean area under the concentration-time curve extrapolated to infinity (AUCinf ) and maximum plasma concentration (Cmax ) increased 14.3-fold and 3.7-fold, respectively. Midazolam coadministered with ritonavir (test) or alone (reference) resulted in 16.5-fold and 3.9-fold increases in midazolam geometric mean AUCinf and Cmax , respectively. After administration of dabigatran with nirmatrelvir/ritonavir (test) or alone (reference), dabigatran geometric mean AUCinf and Cmax increased 1.9-fold and 2.3-fold, respectively. Dabigatran coadministered with ritonavir (test) or alone (reference) resulted in a 1.7-fold increase in dabigatran geometric mean AUCinf and Cmax . Midazolam or dabigatran exposures were generally comparable when coadministered with nirmatrelvir/ritonavir or ritonavir alone, with a slightly higher dabigatran Cmax with nirmatrelvir/ritonavir vs. ritonavir alone. Nirmatrelvir/ritonavir was generally safe when administered with or without midazolam or dabigatran. No serious or severe adverse events were reported. Coadministration of midazolam or dabigatran with nirmatrelvir/ritonavir increased systemic exposure of midazolam or dabigatran. Midazolam exposures were comparable when coadministered with nirmatrelvir/ritonavir or ritonavir alone, suggesting no incremental effect of nirmatrelvir. Dabigatran Cmax was slightly higher when coadministered with nirmatrelvir/ritonavir compared with of ritonavir alone, suggesting a minor incremental effect of nirmatrelvir.

Effect of Fluconazole on the Pharmacokinetics of Pyrotinib Maleate: A Single-Center, Open, Single-Dose, Self-Controlled Study in Healthy Chinese Participants

What Is Known and Objective. Pyrotinib maleate, also known as pyrotinib, is an irreversible dual receptor tyrosine kinase inhibitor that primarily targets the epidermal growth factor receptor (EGFR) and human epidermal growth factor receptor 2 (HER2). Cytochrome P450 3A4 (CYP3A4) enzyme mainly catalyzes pyrotinib, and its metabolism is influenced apparently by CYP3A4 strong inhibitor, but the effect of CYP3A4 moderate inhibitor is still unclear as a moderate inhibitor of CYP3A4 enzyme. This study evaluated the effect of fluconazole, a widespread antifungal medication, on the pharmacokinetics and safety tolerance of pyrotinib. Methods. This study was an open, single-dose, and self-controlled clinical trial. Eighteen healthy Chinese participants were enrolled in this study. All participants were administered fluconazole on days 6–18 and pyrotinib on days 1 and 9. The maximum plasma concentration (Cmax), time to Cmax (Tmax), area under the concentration–time curve from time 0 to the last measurable concentration (AUC0−t), area under the concentration–time curve from time 0 extrapolated to infinity (AUC0−∞), terminal elimination half-life (t1/2), apparent volume of distribution (Vz/F), and apparent clearance (CL/F) were calculated using WinNonlin software (version 8.1). Safety tolerance was assessed throughout the process. Results and Discussion. Compared with the single administration of pyrotinib, the exposure level was enhanced significantly after the coadministration of pyrotinib and fluconazole. The geometric mean ratios (pyrotinib + fluconazole/pyrotinib alone) of Cmax, AUC0−t, and AUC0−∞ were 2.16, 3.6, and 3.5, respectively. The parameter of t1/2 is 14.16 h and 24.03 h, and CL/F is 275.06 L/h and 78.42 L/h, for pyrotinib alone and with fluconazole. No serious adverse events were reported in this trial, and no participant withdrew from the trial because of adverse events. What Is New and Conclusion. The PK profile of pyrotinib, a CYP3A4 substrate, was significantly influenced by fluconazole, with increased exposure levels and prolonged t1/2. Dosage adjustment is suggested for the clinical application of pyrotinib when coadministered with fluconazole or other CYP3A4 inhibitors/inducers.

Physiologically-based pharmacokinetic modeling to predict drug-drug interaction of enzalutamide with combined P-gp and CYP3A substrates

Enzalutamide is known to strongly induce cytochrome P450 3A4 (CYP3A4). Furthermore, enzalutamide showed induction and inhibition of P-glycoprotein (P-gp) in in vitro studies. A clinical drug-drug interaction (DDI) study between enzalutamide and digoxin, a typical P-gp substrate, suggested enzalutamide has weak inhibitory effect on P-gp substrates. Direct oral anticoagulants (DOACs), such as apixaban and rivaroxaban, are dual substrates of CYP3A4 and P-gp, and hence it is recommended to avoid co-administration of these DOACs with combined P-gp and strong CYP3A inducers. Enzalutamide’s net effect on P-gp and CYP3A for apixaban and rivaroxaban plasma exposures is of interest to physicians who treat patients for venous thromboembolism with prostate cancer. Accordingly, a physiologically-based pharmacokinetic (PBPK) analysis was performed to predict the magnitude of DDI on apixaban and rivaroxaban exposures in the presence of 160 mg once-daily dosing of enzalutamide. The PBPK models of enzalutamide and M2, a major metabolite of enzalutamide which also has potential to induce CYP3A and P-gp and inhibit P-gp, were developed and verified as perpetrators of CYP3A-and P-gp-mediated interaction. Simulation results predicted a 31% decrease in AUC and no change in Cmax for apixaban and a 45% decrease in AUC and a 25% decrease in Cmax for rivaroxaban when 160 mg multiple doses of enzalutamide were co-administered. In summary, enzalutamide is considered to decrease apixaban and rivaroxaban exposure through the combined effects of CYP3A induction and net P-gp inhibition. Concurrent use of these drugs warrants careful monitoring for efficacy and safety.

Prediction of Sites of Metabolism of CYP3A4 Substrates Utilizing Docking-Derived Geometric Features.

Cytochrome P450 3A4 (CYP3A4) is one of the major drug-metabolizing enzymes in the human body and is responsible for the metabolism of ∼50% of clinically used drugs. Therefore, the identification of the compound's sites of metabolism (SOMs) mediated by CYP3A4 is of utmost importance in the early stage of drug discovery and development. Herein, docking-based approaches incorporating geometric features were used for SOMs prediction of CYP3A4 substrates. The cross-docking poses of a relatively large data set containing 474 substrates were analyzed in depth, and a widely observed geometric pattern called the close proximity of SOMs was derived from the poses. On the basis of the close proximity, several structure-based models have been constructed, which demonstrated better performance than those structure-based models using the criterion of Fe-SOM distance. For further improving the prediction performance, the structure-based models were also combined with the well-known ligand-based model SMARTCyp. One combined model exhibited good performance on the SOMs prediction of an external substrate set containing kinase inhibitors, PROTACs, approved drugs, and some lead compounds.

Management of Drug Interactions with Inducers: Onset and Disappearance of Induction on Cytochrome P450 3A4 and Uridine Diphosphate Glucuronosyltransferase 1A1 Substrates.

People living with HIV may present co-morbidities requiring the initiation and subsequently the discontinuation of medications with inducing properties. The time to reach maximal enzyme induction and to return to baseline enzyme levels has not been thoroughly characterized. The aim of this study was to evaluate the onset and disappearance of dolutegravir [uridine diphosphate glucuronosyltransferase (UGT) 1A1 and cytochrome P450 (CYP) 3A4 substrate] and raltegravir (UGT1A1 substrate) induction with strong and moderate inducers using physiologicallybased pharmacokinetic (PBPK) modeling. The predictive performance of the PBPK model to simulate dolutegravir and raltegravir pharmacokinetics and to reproduce the strength of induction was verified using clinical drug-drug interaction studies (steady-state induction) and switch studies (residual induction). The model was considered verified when the predictions were within 2-fold of the observed data. One hundred virtual individuals (50% female) were generated to simulate the unstudied scenarios. The results were used to calculate the fold-change in CYP3A4 and UGT1A1 enzyme levels upon initiation and discontinuation of strong (rifampicin) or moderate (efavirenz or rifabutin) inducers. The time for reaching maximal induction and subsequent disappearance of CYP3A4 induction was 14 days for rifampicin and efavirenz but 7 days for rifabutin. The distinct timelines for the moderate inducers relate to their different half-lives and plasma concentrations. The induction and de-induction processes were more rapid for UGT1A1. Our simulations support the common practice of maintaining the adjusted dosage of a drug for another 2 weeks after stopping an inducer. Furthermore, our simulations suggest that an inducer should be administered for at least 14 days before conducting interaction studies to reach maximal induction.

Evaluation of the Drug-Drug Interaction Potential of Ensitrelvir Fumaric Acid with Cytochrome P450 3A Substrates in Healthy Japanese Adults.

Management of drug-drug interactions (DDIs) for ensitrelvir, a novel 3-chymotrypsin-like protease inhibitor of SARS-CoV-2 infection is crucial. A previous clinical DDI study of ensitrelvir with midazolam, a clinical index cytochrome P450 (CYP) 3A substrate, demonstrated that ensitrelvir given for 5 days orally with a loading/maintenance dose of 750/250 mg acted as a strong CYP3A inhibitor. The objectives of this study were to investigate the effect of ensitrelvir on the pharmacokinetics of CYP3A substrates, dexamethasone, prednisolone and midazolam, and to assess the pharmacokinetics, safety, and tolerability of ensitrelvir following multiple-dose administration of ensitrelvir. This was a Phase 1, multicenter, single-arm, open-label study in healthy Japanese adult participants. The effects of multiple doses of ensitrelvir in the fasted state on the pharmacokinetics of dexamethasone, prednisolone, and midazolam were investigated. Ensitrelvir was administered from Day 1 through Day 5, with a loading/maintenance dose of 750/250 mg for the dexamethasone and prednisolone cohorts whereas 375/125 mg for the midazolam cohort. Either dexamethasone, prednisolone, or midazolam was administered alone (Day -2) or in combination with ensitrelvir (Day 5) in each of the cohorts. Additionally, dexamethasone or prednisolone was administered on Days 9 and 14. The pharmacokinetic parameters of ensitrelvir, dexamethasone, prednisolone, and midazolam were calculated based on their plasma concentration data with non-compartmental analysis. In safety assessments, the nature, frequency, and severity of treatment-emergent adverse events were evaluated and recorded. The area under the concentration-time curve (AUC) ratio of dexamethasone on Day 5 was 3.47-fold compared with the corresponding values for dexamethasone alone on Day -2 and the effect diminished over time after the last dose of ensitrelvir. No clinically meaningful effect was observed for prednisolone. The AUC ratio of midazolam was 6.77-fold with ensitrelvir 375/125 mg suggesting ensitrelvir at 375/125 mg strongly inhibits CYP3A similar to that at 750/250 mg. No new safety signals with ensitrelvir were reported during the study. The inhibitory effect for CYP3A was confirmed after the last dose of ensitrelvir, and the effect diminished over time. In addition, ensitrelvir at 375/125 mg showed CYP3A inhibitory potential similar to that at 750/250 mg. These findings can be used as a clinical recommendation for prescribing ensitrelvir with regard to concomitant medications. Japan Registry of Clinical Trials identifier: jRCT2031210202.

Evaluation of the effect of ritlecitinib on the pharmacokinetics of caffeine in healthy participants.

This clinical study was conducted to evaluate the impact of ritlecitinib on the pharmacokinetics of caffeine, a cytochrome P450 1A2 (CYP1A2) substrate. In this single-centre, single-arm, open-label, fixed-sequence study, healthy participants received a single 100-mg dose of caffeine on 2 separate occasions: on Day 1 of Period 1 as monotherapy and on Day 8 of Period 2 after oral administration of ritlecitinib 200 mg once daily for 8days. Serial blood samples were collected and analysed using a validated liquid chromatography-mass spectrometry assay. Pharmacokinetic parameters were estimated by using a noncompartmental method. Safety was monitored by physical examination, vital signs, electrocardiograms and laboratory assessments. Twelve participants were enrolled and completed the study. Coadministration of caffeine 100 mg in the presence of steady-state levels of ritlecitinib (200 mg once daily) increased caffeine exposure compared with caffeine given alone. Area under the curve to infinity and maximum concentration of caffeine increased by approximately 165 and 10%, respectively, when coadministered with ritlecitinib. The ratios of the adjusted geometric means (90% confidence interval) for caffeine area under the curve to infinity and maximum concentration were 265.14% (234.12-300.26%) and 109.74% (103.90-15.91%), respectively, when caffeine was coadministered with steady-state ritlecitinib (test) compared with its administration alone (reference). Multiple doses of ritlecitinib when coadministered with a single dose of caffeine were generally safe and well tolerated in healthy participants. Ritlecitinib is a moderate inhibitor of CYP1A2 and can increase systemic exposures of CYP1A2 substrates.

Dynamic Ir(III) Photosensors for the Major Human Drug-Metabolizing Enzyme Cytochrome P450 3A4.

Probing the activity of cytochrome P450 3A4 (CYP3A4) is critical for monitoring the metabolism of pharmaceuticals and identifying drug-drug interactions. A library of Ir(III) probes that detect occupancy of the CYP3A4 active site were synthesized and characterized. These probes show selectivity for CYP3A4 inhibition, low cellular toxicity, Kd values as low as 9 nM, and are highly emissive with lifetimes up to 3.8 μs in cell growth media under aerobic conditions. These long emission lifetimes allow for time-resolved gating to distinguish probe from background autofluorescence from growth media and live cells. X-ray crystallographic analysis revealed structure-activity relationships and the preference or indifference of CYP3A4 toward resolved stereoisomers. Ir(III)-based probes show emission quenching upon CYP3A4 binding, then emission increases following displacement with CYP3A4 inhibitors or substrates. Importantly, the lead probes inhibit the activity of CYP3A4 at concentrations as low as 300 nM in CYP3A4-overexpressing HepG2 cells that accurately mimic human hepatic drug metabolism. Thus, the Ir(III)-based agents show promise as novel chemical tools for monitoring CYP3A4 active site occupancy in a high-throughput manner to gain insight into drug metabolism and drug-drug interactions.