Cytochrome P450 3A Enzymes Research Articles

Effect of itraconazole on the safety and pharmacokinetics of antitumor SHR6390

The experimental drug SHR6390 has anti-tumor activity as a cyclin dependent kinase 4/6 inhibitor and is metabolized primarily by the cytochrome P450 3A4 enzyme. Therefore, The purpose of this trial was to evaluate the safety and pharmacokinetics of SHR6390, a potent cytochrome P450 3A4 inhibitor, in healthy Chinese subjects. In this trial study, 18 subjects received a single oral dose of SHR6390 50 mg on day 1, multiple doses of 200 mg itraconazole on days 12–24 for 13 days, and a single oral dose of SHR6390 50 mg on day 15. After coadministration with itraconazole, the maximum plasma concentration (Cmax) of SHR6390 increased by 70.7% (from 14.3 ng/ml to 24.5 ng/ml), and the area under the time curve from 0 to T (AUC0-T) increased by 110.8% from 468 h∙ng/mL to 988 h∙ng/mL. The area under the concentration-time curve extrapolated to ∞(AUC0-∞) increases from 509 H∙ng/mL to 1,040 h∙ng/mL, an increase of 105.1%. Oral gap (CL/F) decreased (47.9 L/h and 98.3 L/h) and apparent volume of distribution (Vz/F) decreased (4190 L and 5890 L). According to common terminology criteria, 15 32 adverse events were reported in 18 subjects (AEs) (27 SHR6390-related AEs and 15 Itraconazole-related AEs), AEs were all Class 1 adverse events. Overall, co-administration of Itraconazole increased the plasma exposure of SHR6390 in healthy subjects. Both SHR6390 alone and co-administration of Itraconazole showed acceptable safety profiles, which warrants further investigation. The experimental drug SHR-6390 of this clinical trial has been applied for registration, which is classified as Chemical drugs Class 1. The study drug SHR6390 registration number:ClinicalTrials.gov Identifier: NCT04423601 (https://clinicaltrials.gov/)

Atorvastatin induced liver injury: A Case Series

Atorvastatin is the most widely used statin for the prevention and treatment of cardiovascular disease. It belongs to the class of drugs called HMG-CoA reductase inhibitors. One of the most significant side effects of statins is liver injury. Liver injury as evidenced by elevation in liver enzymes occurs in some patients treated with atorvastatin 10mg to 80mg. Therefore, Liver function tests (LFTs) need to be assessed before initiating atorvastatin therapy and to be repeated thereafter. Here we discuss three cases of liver enzyme elevations within 24hrs of atorvastatin treatment. Liver enzymes were completely returned to baseline after discontinuing the therapy. The risk factors of atorvastatin induced liver injury are increased age, chronic diseases, and coadministration of drugs metabolised by Cytochrome P450 3A (CYP3A) enzyme.

Predicting drug-drug interactions with physiologically based pharmacokinetic/pharmacodynamic modelling and optimal dosing of apixaban and rivaroxaban with dronedarone co-administration

BackgroundThe concurrent administration of dronedarone and oral anti-coagulants is common because both are used in managing atrial fibrillation (AF). Dronedarone is a moderate inhibitor of the cytochrome P450 3A4 (CYP3A4) enzyme and P-glycoprotein (P-gp). Apixaban and rivaroxaban are P-gp and CYP3A4 substrates. This study aims to investigate the impact of exposure and bleeding risk of apixaban or rivaroxaban when co-administered with dronedarone using physiologically based pharmacokinetic/pharmacodynamic analysis. MethodsModeling and simulation were conducted using Simcyp® Simulator. The parameters required for dronedarone modeling were collected from the literature. The developed dronedarone physiologically based pharmacokinetic (PBPK) model was verified using reported drug-drug interactions (DDIs) between dronedarone and CYP3A4 and P-gp substrates. The model was applied to evaluate the DDI potential of dronedarone on the exposure of apixaban 5 mg every 12 h or rivaroxaban 20 mg every 24 h in geriatric and renally impaired populations. DDIs precipitating major bleeding risks were assessed using exposure-response analyses derived from literature. ResultsThe model accurately described the pharmacokinetics of orally administered dronedarone in healthy subjects and accurately predicted DDIs between dronedarone and four CYP3A4 and P-gp substrates with fold errors <1.5. Dronedarone co-administration led to a 1.29 (90 % confidence interval (CI): 1.14–1.50) to 1.31 (90 % CI: 1.12–1.46)-fold increase in the area under concentration-time curve for rivaroxaban and 1.33 (90 % CI: 1.15–1.68) to 1.46 (90 % CI: 1.24–1.92)-fold increase for apixaban. The PD model indicated that dronedarone co-administration might potentiate the mean major bleeding risk of apixaban with a 1.45 to 1.95-fold increase. However, the mean major bleeding risk of rivaroxaban was increased by <1.5-fold in patients with normal or impaired renal function. ConclusionsDronedarone co-administration increased the exposure of rivaroxaban and apixaban and might potentiate major bleeding risks. Reduced apixaban and rivaroxaban dosing regimens are recommended when dronedarone is co-administered to patients with AF.

Down-regulation of hepatic cytochromes P450 1A1 and 1A2 by arsenic trioxide (ATO) in vivo and in vitro: A role of heme oxygenase 1

Arsenic trioxide (ATO) has evolved from an environmental threat to a successful therapy for acute promyelocytic leukemia (APL) and probably for solid tumors in the future. However, its efficacy comes at a cost of multi-organ toxicity whose mechanism remains unresolved. Arsenicals have been reported to modulate cytochrome P450 1A (CYP1A) enzymes, thus modifying activation/detoxification of drugs/procarcinogens. Therefore, this study aimed to investigate the possible effects of ATO on CYP1A1 and CYP1A2, in absence and presence of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) using in vivo and in vitro models. For this purpose, C57BL/6 mice were intraperitoneally injected with 8 mg/kg ATO with or without 15 μg/kg TCDD for 6 and 24 h. Furthermore, HepG2 cells were treated with ATO (1, 5, and 10 μM) with or without 1 nM TCDD for 6 and 24 h. ATO significantly inhibited TCDD-mediated induction of CYP1A1/1A2 mRNA, protein, and activity in both models. ATO differentially modulated CYP1A1/1A2 basal levels in vivo. We also demonstrated that ATO downregulates CYP1A through inhibiting the transcriptional activation of its regulatory element at both basal and inducible levels. Additionally, ATO significantly induced mRNA and protein of heme oxygenase 1 (HMOX1) in vivo and in vitro. In HepG2 cells, inhibition of HMOX1 by tin (IV) mesoporphyrin (IX) (SnMP) resulted in a partial restoration of the TCDD-mediated induction of CYP1A1 activity that was inhibited by ATO co-exposure. Our findings show that ATO alters both constitutive and inducible CYP1A1/1A2 expressions through transcriptional and HMOX1-mediated post-translational mechanisms. This implies the possible involvement of ATO in clearance-related consequences for the substrates of these enzymes such as drug-drug interactions or suboptimal toxicant elimination.

In Silico Prediction of the Metabolic Resistance of Vitamin D Analogs against CYP3A4 Metabolizing Enzyme.

The microsomal cytochrome P450 3A4 (CYP3A4) and mitochondrial cytochrome P450 24A1 (CYP24A1) hydroxylating enzymes both metabolize vitamin D and its analogs. The three-dimensional (3D) structure of the full-length native human CYP3A4 has been solved, but the respective structure of the main vitamin D hydroxylating CYP24A1 enzyme is unknown. The structures of recombinant CYP24A1 enzymes have been solved; however, from studies of the vitamin D receptor, the use of a truncated protein for docking studies of ligands led to incorrect results. As the structure of the native CYP3A4 protein is known, we performed rigid docking supported by molecular dynamic simulation using CYP3A4 to predict the metabolic conversion of analogs of 1,25-dihydroxyvitamin D2 (1,25D2). This is highly important to the design of novel vitamin D-based drug candidates of reasonable metabolic stability as CYP3A4 metabolizes ca. 50% of the drug substances. The use of the 3D structure data of human CYP3A4 has allowed us to explain the substantial differences in the metabolic conversion of the side-chain geometric analogs of 1,25D2. The calculated free enthalpy of the binding of an analog of 1,25D2 to CYP3A4 agreed with the experimentally observed conversion of the analog by CYP24A1. The metabolic conversion of an analog of 1,25D2 to the main vitamin D hydroxylating enzyme CYP24A1, of unknown 3D structure, can be explained by the binding strength of the analog to the known 3D structure of the CYP3A4 enzyme.

Homeostatic regulation of the aryl hydrocarbon receptor-cytochrome P450 1a axis by Scutellaria baicalensis-Coptis chinensis herb pair and its main constituents

Ethnopharmacological relevanceScutellaria baicalensis (SB) and Coptis chinensis (CC) are widely used traditional Chinese medicine (TCM) for “heat-clearing and damp-drying” and “purging fire and detoxifying”. SB-CC are commonly used as a herbal pair for synergistic treatment of various diseases such as bacteria-related infections, metabolic syndromes, and some inflammatory disorders. This herbal pair is commonly used in many famous TCM formula, like Huang-Lian-Jie-Du, Gegen-Qinlian, Banxia Xiexin decoction. Aryl hydrocarbon receptor (AHR) plays an essential role in the disposition of both xenobiotics and endogenous substances through the induction of cytochrome P450 1A (CYP1A) enzymes. Regulation of the AHR-CYP1A axis is increasingly implicated in drug-drug and drug-herb interactions. Research on SB-CC for regulatory effect on the AHR-CYP1A axis is only limited to few compounds. Aim of the studyThis study aimed to systematically investigate the regulatory effect of SB-CC and its main constitutes on the AHR-CYP1A axis in vitro and in vivo. Materials and methodsThe livers of mice treated with SB-CC extract were subjected to RNA-sequencing (RNA-seq). The key target genes related to drug metabolism were screened, and the differential expression genes (DEGs) were validated by qRT-PCR, Western blot, and enzyme activity assay. Luciferase reporter gene, qRT-PCR, and Western blot assays were used to determine whether SB-CC and their main constituents could activate AHR and regulate CYP1A expression in HepG2 cells. The effect of SB-CC on the pharmacokinetics of phenacetin, a CYP1A substrate, were further observed in mice to test the net effect of SB-CC on CYP1A functions. The potential CYP1A inhibitors in SB-CC were screened and their inhibitory mechanisms were also studied using human liver microsomes. ResultsAHR and drug metabolism system, especially CYP1A1 and CYP1A2, were strongly affected in the liver of SB-CC-treated mice. These results were further validated by the findings that SB-CC increased CYP1A's mRNA, protein expression and activity in mouse liver. In HepG2 cells, SB, CC, baicalin, baicalein, chrysin, oroxylin A, berberine, coptisine and epiberberine increased CYP1A1 mRNA expression in an AHR-dependent way. Interestingly, SB-CC treatment for 14 days only slightly increased the systemic exposure of paracetamol in mice. In the CYP1A inhibition assay, SB, CC, baicalin, baicalein, wogonoside, wogonin, chrysin, oroxylin A, scutellarein, columbamine, coptisine, palmatine, epiberberine, and berberrubine inhibited CYP1A activity in different degree. ConclusionsThese results suggested that SB-CC exerted dual regulatory effect on the AHR-CYP1A axis by increasing CYP1A expression but simultaneously inhibiting CYP1A activity, which may contribute to a tight modulation of AHR signaling for homeostatic control.

A novel approach to predict the comprehensive EROD potency: Mechanism-based curve fitting of CYP1A1 activity by PAHs

Cytochrome P450 1A1 (CYP1A1) plays critical roles in polycyclic aromatic hydrocarbon (PAH) toxicity, including DNA adduction and ROS generation. Therefore, CYP1A1 activity quantified by the 7-ethoxyresorufin-O-deethylase (EROD) assay (named EROD potency) has been considered a typical biomarker of PAH exposure and toxicity. The EROD dose–response curve always presents a biphasic style, increasing at low concentrations and decreasing at high concentrations of PAHs, but relative effect potency (REP) commonly used in PAH risk assessment is only involved in the increasing phase. In this study, a full bell-shaped EROD curve fitting formula Eq. (1) was obtained by considering both CYP1A1 mRNA induction and enzyme inhibition to completely assess the EROD potency of PAHs. Correspondingly, in silico models of QSAR and docking methods successfully predicted the full EROD curves of PAHs, and the structure-activity relationship indicated that PAHs with heavy molecular weight and large diameter showed stronger EROD potency. Further EROD potency with predicted curve parameters (EC50,ind and area index) was confirmed by the reported REP (R2 = 0.697–0.977) and experimental data from human and mouse cells (R2 = 0.700–0.804). This study provides a novel curve fitting for the EROD dose–response relationship and a prediction model for PAH EROD potency.

Development of Physiology Based Pharmacokinetic Model to Predict the Drug Interactions of Voriconazole and Venetoclax.

Venetoclax (VEN), an anti-tumor drug that is a substrate of cytochrome P450 3A enzyme (CYP3A4), is used to treat leukemia. Voriconazole (VCZ) is an antifungal medication that inhibits CYP3A4. The goal of this study is to predict the effect of VCZ on VEN exposure. Two physiological based pharmacokinetics (PBPK) models were developed for VCZ and VEN using the bottom-up and top-down method. VCZ model was also developed to describe the effect of CYP2C19 polymorphism on its pharmacokinetics (PK). The reversible inhibition constant (Ki) of VCZ for CYP3A4 was calibrated using drug-drug interaction (DDI) data of midazolam and VCZ. The clinical verified VCZ and VEN model were used to predict the DDI of VCZ and VEN at clinical dosing scenario. VCZ model predicted VCZ exposure in the subjects of different CYP2C19 genotype and DDI related fold changes of sensitive CYP3A substrate with acceptable prediction error. VEN model can capture PK of VEN with acceptable prediction error. The DDI PBPK model predicted that VCZ increased the exposure of VEN by 4.5-9.6 fold. The increase in VEN exposure by VCZ was influenced by subject's CYP2C19 genotype. According to the therapeutic window, VEN dose should be reduced to 100mg when co-administered with VCZ. The PBPK model developed here could support individual dose adjustment of VEN and DDI risk assessment. Predictions using the robust PBPK model confirmed that the 100mg dose adjustment is still applicable in the presence of VCZ with high inter-individual viability.

Recommendations for the Management of Drug-Drug Interactions Between the COVID-19 Antiviral Nirmatrelvir/Ritonavir (Paxlovid) and Comedications.

The coronavirus disease 2019 (COVID‐19) antiviral nirmatrelvir/ritonavir (Paxlovid) has been granted authorization or approval in several countries for the treatment of patients with mild to moderate COVID‐19 at high risk of progression to severe disease and with no requirement for supplemental oxygen. Nirmatrelvir/ritonavir will be primarily administered outside the hospital setting as a 5‐day course oral treatment. The ritonavir component boosts plasma concentrations of nirmatrelvir through the potent and rapid inhibition of the key drug‐metabolizing enzyme cytochrome P450 (CYP) 3A4. Thus nirmatrelvir/ritonavir, even given as a short treatment course, has a high potential to cause harm from drug–drug interactions (DDIs) with other drugs metabolized through this pathway. Options for mitigating risk from DDIs with nirmatrelvir/ritonavir are limited due to the clinical illness, the short window for intervention, and the related difficulty of implementing clinical monitoring or dosage adjustment of the comedication. Pragmatic options are largely confined to preemptive or symptom‐driven pausing of the comedication or managing any additional risk through counseling. This review summarizes the effects of ritonavir on drug disposition (i.e., metabolizing enzymes and transporters) and discusses factors determining the likelihood of having a clinically significant DDI. Furthermore, it provides a comprehensive list of comedications likely to be used in COVID‐19 patients which are categorized according to their potential DDI risk with nirmatrelvir/ritonavir. It also discusses recommendations for the management of DDIs which balance the risk of harm from DDIs with a short course of ritonavir, against unnecessary denial of nirmatrelvir/ritonavir treatment.

Paxlovid (Nirmatelvir/Ritonavir) and Tacrolimus Drug-Drug Interaction in a Kidney Transplant Patient with SARS-2-CoV infection: A Case Report

The novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic has had a significant impact on communities and health systems. New antiviral medications against this disease have not been properly tested yet, and their efficiency, side effects, and drug–drug interactions are not entirely known. Organ transplant recipients receive immunosuppressive medications such as tacrolimus to prevent graft rejection. Tacrolimus is metabolized by the cytochrome P450 3A4 enzyme system. Many medications can either induce or inhibit this enzyme and affect the level. Awareness of possible drug–drug interactions is vital because tacrolimus levels should be kept within a specific narrow range determined by the recipient's immunologic risk. Underexposure increases the risk of graft rejection, whereas overexposure may lead to adverse effects. Paxlovid, a novel antiviral medication approved for emergency use to treat SARS-CoV-2, is a combination of nirmatrelvir and ritonavir, a cytochrome P450 34A inhibitor. In this case report, we present a case of a kidney transplant patient receiving tacrolimus treated with Paxlovid, leading to an abruptly high tacrolimus level, significant symptoms, treatment interruption, and acute kidney injury. We conclude that the drug–drug interaction between Paxlovid and tacrolimus is indeed robust and noteworthy and leads to high tacrolimus levels and its metabolites, adverse effects, and acute kidney injury. Physicians managing immunocompromised patients receiving tacrolimus should be aware of this significant drug–drug interaction and consider other options or reduction of daily tacrolimus dose during treatment in addition to timely monitoring of both tacrolimus levels and serum creatinine. Consulting with the transplant pharmacist is foremost in alerting for these interactions.

Utilization of CYP3A‐Specific Inhibitors to Study Cytochrome P450 CYP3A7 Activity in Neonatal Human Liver Microsomes

CYP3A7 is a member of the cytochrome P450 (CYP) 3A enzyme sub‐family that accounts for ~50% of the total CYP content in neonate and fetal livers. The amount of other CYP3A enzymes, CYP3A4 and CYP3A5, expressed in neonates is low but highly variable, and therefore, the activity of individual enzyme isoforms is difficult to differentiate. Recent studies report that CYP3cide, clobetasol propionate, and azamulin are specific inhibitors for CYP3A4, CYP3A5, and CYP3A4/5, respectively. However, the inhibitory effects towards CYP3A7 were not investigated for the latter two compounds, and the use of these compounds to study CYP3A7 activity has not been reported/investigated. Thus, we sought to characterize these compounds further and utilize them to isolate and study the activity of CYP3A7 in neonatal human liver microsomes. We have examined three substrate probes—dibenzylfluorescein, luciferin‐PPXE, and midazolam—to determine the IC50 values and mechanism‐based inactivation parameters (Ki, Kinact) of the purported isoform specific inhibitors. We discovered that azamulin was unable to selectively inhibit any of the CYP3As, but CYP3cide and clobetasol propionate exhibited IC50values for CYP3A4 and CYP3A5 two to three orders of magnitude lower than CYP3A7. CYP3cide and clobetasol propionate were further tested in mixtures of CYP3A4, CYP3A5, and CYP3A7 to mimic the neonatal human liver microsome environment and ascertain their effectiveness in isolating CYP3A7 activity. We were able to inhibit CYP3A4 without disturbing CYP3A7 activity using CYP3cide at concentrations below 5 μM. The majority of CYP3A5 activity was inhibited using low clobetasol propionate concentrations, but using higher concentrations also inhibited CYP3A7 activity due to its lower selectivity. These findings provide valuable insight regarding testing conditions to investigate the metabolism of new drug candidates and help determine drug safety in neonates.

Examination of the Impact of CYP3A4/5 on Drug–Drug Interaction between Schizandrol A/Schizandrol B and Tacrolimus (FK-506): A Physiologically Based Pharmacokinetic Modeling Approach

Schizandrol A (SZA) and schizandrol B (SZB) are two active ingredients of Wuzhi capsule (WZC), a Chinese proprietary medicine commonly prescribed to alleviate tacrolimus (FK-506)-induced hepatoxicity in China. Due to their inhibitory effects on cytochrome P450 (CYP) 3A enzymes, SZA/SZB may display drug–drug interaction (DDI) with tacrolimus. To identify the extent of this DDI, the enzymes’ inhibitory profiles, including a 50% inhibitory concentration (IC50) shift, reversible inhibition (RI) and time-dependent inhibition (TDI) were examined with pooled human-liver microsomes (HLMs) and CYP3A5-genotyped HLMs. Subsequently, the acquired parameters were integrated into a physiologically based pharmacokinetic (PBPK) model to quantify the interactions between the SZA/SZB and the tacrolimus. The metabolic studies indicated that the SZB displayed both RI and TDI on CYP3A4 and CYP3A5, while the SZA only exhibited TDI on CYP3A4 to a limited extent. Moreover, our PBPK model predicted that multiple doses of SZB would increase tacrolimus exposure by 26% and 57% in CYP3A5 expressers and non-expressers, respectively. Clearly, PBPK modeling has emerged as a powerful approach to examine herb-involved DDI, and special attention should be paid to the combined use of WZC and tacrolimus in clinical practice.

Preclinical studies of the triazolo[1,5-a]pyrimidine derivative WS-716 as a highly potent, specific and orally active P-glycoprotein (P-gp) inhibitor

Multidrug resistance (MDR) is the main cause of clinical treatment failure and poor prognosis in cancer. Targeting P-glycoprotein (P-gp) has been regarded as an effective strategy to overcome MDR. In this work, we reported our preclinical studies of the triazolo[1,5-a]pyrimidine-based compound WS-716 as a highly potent, specific, and orally active P-gp inhibitor. Through direct binding to P-gp, WS-716 inhibited efflux function of P-gp and specifically reversed P-gp-mediated MDR to paclitaxel (PTX) in multiple resistant cell lines, without changing its expression or subcellular localization. WS-716 and PTX synergistically inhibited formation of colony and 3D spheroid, induced apoptosis and cell cycle arrest at G2/M phase in resistant SW620/Ad300 cells. In addition, WS-716 displayed minimal effect on the drug-metabolizing enzyme cytochrome P4503A4 (CYP3A4). Importantly, WS-716 increased sensitivity of both pre-clinically and clinically derived MDR tumors to PTX in vivo with the T/C value of 29.7% in patient-derived xenograft (PDX) models. Relative to PTX treatment alone, combination of WS-716 and PTX caused no obvious adverse reactions. Taken together, our preclinical studies revealed therapeutic promise of WS-716 against MDR cancer, the promising data warrant its further development for cancer therapy.

Hepatic drug metabolism in older people with body composition changes.

Dosage adjustment is essential in older individuals because they are prone to experience a decline in liver function and changes in body composition. However, quantitative tests or equations for evaluating the activity of hepatic drug metabolism have not yet been clearly established. We examined hepatic drug metabolism activities in older individuals, focusing on changes in body composition parameters. Lansoprazole and nifedipine, substrates of the metabolic enzymes cytochrome P450 (CYP) 2C19 and 3A4, respectively, were selected to study hepatic drug metabolism. Residual samples from blood test for older patients were evaluated to determine drug metabolism. The body composition of relevant patients was determined by analyzing characteristic parameters of skeletal muscle mass index (SMI), handgrip strength (HGS) and hepatic steatosis index (HSI). The differences in hepatic drug metabolism were studied statistically among categories in terms of the cut-off value of these parameters. Older male patients receiving lansoprazole and nifedipine in the low SMI (<7.0 kg/m2 ) category showed an 85-90% reduction in respective CYP2C19 and CYP3A4 metabolic activities compared with the normal SMI category. For the female patients, CYP2C19 and CYP3A4 metabolic activities showed no significant correlation with SMI and HGS. Fatty liver disease (HSI ≥36) was found to reduce CYP2C19 metabolic activity particularly in older female patients. Low CYP2C19 metabolic activity was statistically correlated with low SMI in male patients and high HSI in female patients, whereas low CYP3A4 metabolic activity was statistically correlated with low HGS in male patients. Geriatr Gerontol Int 2022; 22: 449-454.

In silico discovery of potential azole-containing mPGES-1 inhibitors by virtual screening, pharmacophore modeling and molecular dynamics simulations

Inhibition of microsomal prostaglandin E2 synthase-1 (mPGES-1) is promising for designing novel nonsteroidal anti-inflammatory drugs, as they lack side-effects associated with inhibition of cyclooxygenase enzymes. Azole compounds are nitrogen-containing heterocycles and have a wide use in medicine and are considered as promising compounds in medicinal chemistry. Various computer-aided drug design strategies are incorporated in this study. Structure-based virtual screening was performed employing various docking programs. Receiver operator characteristic (ROC) curves were used to evaluate the selectivity of each program. Furthermore, scoring power of Autodock4 and Autodock Vina was assessed by Pearson’s correlation coefficients. Pharmacophore models were generated and Güner-Henry score of the best model was calculated as 0.89. Binding modes of the final 10 azole compounds were analyzed and further investigation of the best binding (− 8.38 kcal/mol) compound was performed using molecular dynamics simulation, revealing that furazan1224 (ZINC001142847306) occupied the binding site of the substrate, prostaglandin H2 (PGH2) and remained stable for 100 ns. Continuous hydrogen bonds and hydrophobic interactions with amino acids in the active site supported the stability of furazan1224 throughout the trajectory. Pharmacokinetic profile showed that furazan1224 lacks the risks of inhibiting cytochrome P450 3A4 enzyme and central nervous system-related side-effects.

Highly sensitive simultaneous quantification of indoxyl sulfate and 3-carboxy-4-methyl-5-propyl-2-furanpropanoic acid in human plasma using ultra-high-performance liquid chromatography coupled with tandem mass spectrometry.

Indoxyl sulfate and 3-carboxy-4-methyl-5-propyl-2-furanpropanoic acid are uremic toxins that accumulate in renal failure and have been reported to decrease the activities of the drug-metabolizing enzyme cytochrome P450 3A and the drug transporter organic anion transporting polypeptides 1B, respectively. In this study, we established and validated an assay for simultaneous quantification of indoxyl sulfate and 3-carboxy-4-methyl-5-propyl-2-furanpropanoic acid in human plasma. The samples were pretreated by solid-phase extraction, and measured by ultra-high-performance liquid chromatography-tandem mass spectrometry. The validation results for this assay were within the acceptable limits recommended by the US Food and Drug Administration, with a lower limit of quantitation of 0.05μg/mL for both indoxyl sulfate and 3-carboxy-4-methyl-5-propyl-2-furanpropanoic acid. Recovery rates of indoxyl sulfate and 3-carboxy-4-methyl-5-propyl-2-furanpropanoic acid corrected by internal standard were 100.7-101.9 and 100.2-101.3%, respectively. Matrix effects of indoxyl sulfate and 3-carboxy-4-methyl-5-propyl-2-furanpropanoic acid corrected by internal standard were 101.1-105.5 and 97.0-103.8%, respectively. The validated assay was used to analyze indoxyl sulfate and 3-carboxy-4-methyl-5-propyl-2-furanpropanoic acid concentrations in the plasma samples of healthy volunteers and patients with chronic kidney disease. All the measured plasma indoxyl sulfate and 3-carboxy-4-methyl-5-propyl-2-furanpropanoic acid concentrations were within the calibration ranges. This novel method may contribute to predicting the activities of drug-metabolizing enzymes and drug transporters in individual patients.

Phase 2 randomized trial of ModraDoc006/r, oral docetaxel plus ritonavir, versus intravenous docetaxel in metastatic castration resistant prostate cancer (mCRPC).

117 Background: Intravenous (IV) docetaxel and oral prednisone is a standard of care regimen in mCRPC. ModraDoc006 is a novel, oral tablet formulation of docetaxel. To enhance bioavailability, it is co-administered with ritonavir (/r), an inhibitor of cytochrome p450 3A4 and P-glycoprotein metabolic enzymes. The oral combination, denoted as ModraDoc006/r, may be superior to IV docetaxel in terms of safety profile, avoiding infusions, patient quality of life (QoL) and overall resource utilization. Safety of ModraDoc006/r in mCRPC was established in a previous phase Ib trial. Methods: We conducted an open label 1:1 randomized study of ModraDoc006/r bi-daily weekly dosing (BIDW) regimen versus IV docetaxel 75 mg/m2 in 21-day cycles. Initially, BIDW 30-20 mg ModraDoc006 combined with 200-100 mg ritonavir was administered on days 1, 8 and 15 of a 21-day cycle. After 39 patients the starting dose was reduced to 20-20 mg BIDW with ritonavir 200 mg in the morning and 100 mg with the evening dose to improve tolerability. All patients received 5 mg oral prednisone twice daily. Primary endpoint was radiographic progression free survival (rPFS) per PCWG-3 criteria. Secondary objectives were ORR, PSA-PFS, time to skeletal related events, disease control rate, duration of response, and safety assessments. Patient reported outcomes and health-related QoL was assessed with treatment satisfaction and FACT-P questionnaires at baseline and after cycles 3, 6 and 10. Results: Enrollment is complete with 101 patients accrued; 49 on IV docetaxel, 52 on ModraDoc006/r (21 on 30-20 mg and 31 on ModraDoc006/r 20-20 mg). 69 patients had measurable disease and median PSA was 67ng/ml (range 0,2 to 1697 ng/ml). IV docetaxel vs ModraDoc006/r 30-20 mg and 20-20 mg demonstrated ORR of 39% vs 50% and 33%, and PSA responses of 57% vs 53% and 48%. All grades neutropenia and neuropathy was noted in 0% and 6% with ModraDoc006/r 20-20 mg therapy and was better than the incidence of 14% (5% ≥G3) and 14% with ModraDoc006/r 30-20 mg, and 27% (20% ≥G3) and 31% respectively on IV docetaxel. Alopecia was also reduced at 23% on ModraDoc006/r 20-20 mg and 29% on ModraDoc006/r 30-20 mg vs 43% on IV docetaxel. GI toxicities were slightly more frequent, but predominantly mild, in the ModraDoc006/r arm: at 20-20 mg dose, all grades diarrhea 32% (3% ≥G3), nausea 29% and stomatitis 3% (G3); at 30-20 mg dose 62% diarrhea (19% ≥G3), 38% nausea and 14% stomatitis (5% ≥G3); and in IV docetaxel, 24% diarrhea, 16% nausea and 10% stomatitis (4% ≥G3). Conclusions: Hematological toxicities and adverse events neuropathy and alopecia were lower with ModraDoc006/r than with IV docetaxel. ModraDoc006/r represents a convenient, oral, tolerable option for patients with mCRPC. ModraDoc006/r has comparable efficacy and a favorable tolerability profile as compared to IV docetaxel and merits further development in patients with mCRPC. Clinical trial information: NCT04028388.

Prediction of CYP-mediated silybin A-losartan pharmacokineticinteractions using physiological based pharmacokinetic modeling.

The concomitant use of herbal products and synthetic drugs necessitates the assessment of their interaction potentials. The herbal hepatoprotective medicine, silybin A inhibits cytochrome P450 (CYP) 2C9 and 3A4 enzymes, thus, may interact with the drugs that are substrates of CYP2C9 and 3A4, such as losartan. The three most prominent genotypes, expressed by CYP2C9 are the CYP2C9*1/*1, CYP2C9*1/*2 and CYP2C9*1/*3. This study aimed to assess silybin A-losartan interaction in different CYP2C9 genotypes using physiological-based pharmacokinetic (PBPK) model approach. The individual PBPK models for silybin A and losartan were developed using PK-Sim®. Losartan pharmacokinetics was predicted with or without co-administration of silybin A in individuals of different CYP2C9 genotypes to find herbal-drug interaction. The predicted drug plasma curves and pharmacokinetic parameters were optimized using parameter identification tool and were compared with reported pharmacokinetic parameters from the published clinical studies for model validation. The silybin-losartan interactions were predicted by change in area under the curve (AUC) and peak systemic concentration (Cmax). The co-treatment of silybin A, 420mg/24h (140mg/8h) with losartan 50mg/24h, exhibited a genotype-dependent change in the losartan's AUC and Cmax. In CYP 2C9*1/*1 genotype, AUC and Cmax of losartan were increased 1.16 and 1.37 folds, respectively falling in a range stipulated for negligible interaction. Increase in AUC and Cmax by 0.873 and 0.294 folds, respectively in CYP2C9*1/*3 after co-administration of silybin A exhibited a minor interaction with losartan. However, in individuals with CYP2C9*1/*2 genotype, the losartan's AUC and Cmax were decreased by 0.01 folds, manifesting a moderate interaction. Hence, in CYP2C9*1/*1 and CYP2C9*1/*3 genotypes, silybin A is a weak CYP inhibitor for losartan while in CYP2C9*1/*2 genotype, the co-administration of silybin consequents into a moderate pharmacokinetic interaction with losartan.

Neratinib causes non-recoverable gut injury and reduces intestinal cytochrome P450 3A enzyme in mice.

Neratinib is a pan-HER tyrosine kinase inhibitor newly approved by FDA in 2017 to treat HER2-positive breast cancer, but the phase III trial of neratinib showed that 96% of the patients taking neratinib experienced diarrhea. So far very few mechanistic studies explore neratinib-induced gastrointestinal (GI) toxicity. Hereby, we performed toxicity studies in mice to characterize the potential mechanism underlying this adverse effect. C57BL/6J mice were separated into three groups A, B, C. Group A received vehicle; group B was orally dosed with 100mg/kg neratinib once daily for 18days. Group C was dosed with 100mg/kg neratinib for 12days and switched to vehicle for 6days. Intestine and liver were collected for further analysis. Human intestine-derived cells were treated with neratinib in vitro. Our results showed that 12days treatment of neratinib caused persistent histological damage in mouse GI tract. Both gene expression and activity of Cyp3a11, the major enzyme metabolizing neratinib in mice was reduced in small intestine. The gene expression of proinflammatory cytokines increased throughout the GI tract. Such damages were not recovered after 6days without neratinib treatment. In addition, in vitro data showed that neratinib was potent in killing human intestine-derived cell lines. Based on such findings, we hypothesized that neratinib downregulates intestinal CYP3A enzyme to cause excessive drug disposition, eventually leading to gut injury.

Management of Psychiatric Disorders in Patients with Hepatic and Gastrointestinal Diseases.

Management of Psychiatric Disorders in Patients with Hepatic and Gastrointestinal Diseases.