Drug Metabolism and Disposition最新文献

Midostaurin and its active metabolites are substrates, mixed inhibitors/inducers of cytochrome P450 (CYP)3A4. The main objective of this study was to develop/refine a physiologically based pharmacokinetic (PBPK) model that incorporated recent clinical drug-drug interaction (DDI) data with midazolam after multiple dosing, to qualify the pharmacokinetic (PK) model simulations of midostaurin and its metabolites, and to apply it to predict untested clinical DDI scenarios with potential comedications. In this study, Simcyp PBPK model of midostaurin and its 2 metabolites was refined from a previously published model associated with endogenous biomarker 4β-hydroxycholesterol data through further optimization of CYP3A4 inhibition/induction potency and was qualified to simulate midostaurin steady-state PK. The incorporation of these parameters enabled DDI predictions of high midostaurin doses on the PK of midazolam and oral contraceptives containing ethinyl estradiol. Additionally, scaling factors for in vitro breast cancer resistance protein and the organic anion transporting polypeptide (OATP1B) inhibition were applied to account for the observed single-dose DDI with rosuvastatin and further extrapolated to predict steady-state DDI with other OATP1B drug substrates. The overall prediction results showed minimal impact of midostaurin at high doses on CYP3A substrates or an effect on the exposure of OATP1B substrates. In summary, the midostaurin PBPK model was retrospectively refined, requalified, and used to simulate the steady-state perpetrator DDI of midostaurin and its metabolites. This PBPK modeling approach and the resulting model predictions were implemented into the midostaurin product label (up to 100 mg twice a day) without the need for confirmatory clinical studies. SIGNIFICANCE STATEMENT: The manuscript describes how a midostaurin PBPK model was updated, verified, and applied to untested scenarios by a predict-learn-confirm cycle as new clinical data become available. It also provides a learning experience of prospective prediction by utilizing endogenous biomarker 4β-hydroxycholesterol to evaluate a complex CYP3A4-mediated drug interaction.

Raloxifene (RX) in the presence of liver microsomes and glutathione (GSH) has shown oxidative bioactivation to reactive intermediates that are conjugated by GSH. L-Ergothioneine (ET) is a naturally occurring sulfhydryl amino acid, similar to GSH, derived from dietary sources with antioxidant properties and reported to accumulate in high concentrations in animals and humans. We hypothesized that ET may have detoxification/conjugation properties similar to GSH. Using rat and human liver microsomes and mouse, rat, dog, monkey, and human hepatocytes, a novel ergothioneine conjugate of raloxifene (RX-ET) (M1) was identified by mass spectrometry. The RX-ET conjugate was further scaled up in rat liver microsomes, isolated, and characterized by high-resolution mass spectrometry and NMR to confirm the structure. A single RX-ET conjugate was characterized and the site of ET conjugation was identified at the C-17 position of RX. The in vivo relevance of this unique conjugate was also established through metabolism studies in intact and bile duct cannulated rats, both untreated and pretreated with ET. In general, the RX-ET conjugate was found in trace amounts in plasma and urine, but in higher concentrations in bile and feces. The major elimination pathway of RX-ET was through biliary elimination. In rats that were pretreated with ET prior to RX administration, significantly larger quantities of ET and RX-ET conjugate were found in in vivo samples. Lastly, these studies suggest that ET conjugation is an additional pathway for scavenging reactive species arising from xenobiotics and may potentially reduce drug-related toxicities. SIGNIFICANCE STATEMENT: Ergothioneine is well known for its antioxidant and free radical scavenging activity. This study identifies its role in conjugating the reactive species arising from the bioactivation of raloxifene in vitro and in vivo suggesting that ergothioneine may act as an additional conjugation pathway similar to glutathione in the disposition of reactive centers or metabolites of xenobiotics.

Distinct differences between sexes exist in various cardiovascular diseases. Moreover, there is a significant correlation between the pathogenesis of cardiac hypertrophy (CH) and the metabolites of arachidonic acid (AA) mediated by cytochrome P450 (CYP) enzymes. The potential link between these sex differences, the levels and the activity of CYP enzymes, and their AA-mediated metabolites remains to be elucidated. Male and female Sprague Dawley rats were injected with 1 mg/kg isoproterenol for 7 days to induce CH. Echocardiography was performed before and after the induction of CH. The hypertrophic markers and CYP enzyme levels were analyzed at the gene and protein levels using real-time polymerase chain reaction and Western blot, respectively. Heart microsomal proteins were incubated with AA, and the resulting metabolites were quantified using liquid chromatography-tandem mass spectrometry. Both sexes showed a significant degree of CH, albeit to varying extents, as the echocardiograph, heart weight/tibial length, and left ventricular parameters proved. In addition, the β/α-myosin heavy chain was 2-fold higher in male compared with female rats. Albeit the 20-hydroxyeicosatetraenoic acid (20-HETE) metabolite formation showed no increase in both sexes, the mid-chain HETEs (5- and 15-HETE) were higher in male rats, which paralleled the increase in the gene and protein levels of CYP1B1. The formation rate of the epoxyeicosatrienoic acids was almost unchanged in female-treated rats, while it was significantly decreased in male-treated rats. Our results suggest sexual dimorphism in the isoproterenol-induced CH in rats, specifically on the level of CYP enzymes and their AA-mediated metabolites. SIGNIFICANCE STATEMENT: Sexual dimorphism was observed in rats following isoproterenol-induced cardiac hypertrophy, with males showing a stronger hypertrophic response. This was linked to higher CYP1B1 gene and protein expression in males, along with sex-related differences in many cytochrome P450 enzyme activities and their mediated arachidonic acid metabolites. These findings emphasized the need for targeted, sex-specific therapeutic strategies for the management and treatment of cardiac hypertrophy and other cardiovascular disorders.

Tanimilast is an inhaled phosphodiesterase-4 inhibitor currently in phase III clinical development for treating chronic obstructive pulmonary disease and asthma. This trial aimed to characterize the pharmacokinetics, mass balance, and metabolite profiling of tanimilast. Eight healthy male volunteers received a single dose of nonradiolabeled tanimilast via powder inhaler (Chiesi NEXThaler [3200 μg]), followed by a concomitant intravenous infusion of a microtracer ([¹⁴C]-tanimilast: 18.5 μg and 500 nCi). Plasma, whole blood, urine, and feces samples were collected up to 240 hours after dose to quantify nonradiolabeled tanimilast, [¹⁴C]-tanimilast, and total-[¹⁴C]. The inhaled absolute bioavailability of tanimilast was found to be approximately 50%. Following intravenous administration of [¹⁴C]-tanimilast, plasma clearance was 22 L/h, the steady-state volume of distribution was 201 L, and the half-life was shorter compared to inhaled administration (14 vs 39 hours, respectively), suggesting that plasma elimination is limited by the absorption rate from the lungs. Seventy-nine percent (71% in feces; 8% in urine) of the intravenous dose was recovered in excreta as total-[¹⁴C]. [¹⁴C]-tanimilast was the major radioactive compound in plasma, whereas no recovery was observed in urine and only 0.3% was recovered in feces, indicating predominant elimination through metabolic route. Importantly, as far as no metabolites accounting for more than 10% of the circulating drug-related exposure in plasma or the administered dose in excreta were detected, no further qualification is required according to regulatory guidelines. This study design successfully characterized the absorption, distribution, and elimination of tanimilast, providing key pharmacokinetic parameters to support its clinical development and regulatory application. SIGNIFICANCE STATEMENT: This trial investigates pharmacokinetic and absorption, distribution, metabolism and excretion profile of tanimilast, an inhaled phosphodiesterase-4 inhibitor for chronic obstructive pulmonary disease and asthma. Eight male volunteers received a dose of nonradiolabeled tanimilast via Chiesi NEXThaler and a microtracer intravenous dose. Results show pivotal pharmacokinetic results for the characterization of tanimilast, excretion route and quantification of significant metabolites, facilitating streamlined clinical development and regulatory approval.

Physiologically based pharmacokinetic (PBPK) models of small molecules have become mainstream in drug development and in academic research. The use of PBPK models is continuously expanding, with the majority of work now focusing on predictions of drug-drug interactions, drug-disease interactions, and changes in drug disposition across lifespan. Recently, publications that use PBPK modeling to predict drug disposition during pregnancy and in organ impairment have increased reflecting the advances in incorporating diverse physiologic changes into the models. Because of the expanding computational power and diversity of modeling platforms available, the complexity of PBPK models has also increased. Academic efforts have provided clear advances in better capturing human physiology in PBPK models and incorporating more complex mathematical concepts into PBPK models. Examples of such advances include the segregated gut model with a series of gut compartments allowing modeling of physiologic blood flow distribution within an organ and zonation of metabolic enzymes and series compartment liver models allowing simulations of hepatic clearance for high extraction drugs. Despite these advances in academic research, the progress in assessing model quality and defining model acceptance criteria based on the intended use of the models has not kept pace. This Minireview suggests that awareness of the need for predefined criteria for model acceptance has increased, but many manuscripts still lack description of scientific justification and/or rationale for chosen acceptance criteria. As artificial intelligence and machine learning approaches become more broadly accepted, these tools offer promise for development of comprehensive assessment for existing observed data and analysis of model performance. SIGNIFICANCE STATEMENT: Physiologically based pharmacokinetic (PBPK) modeling has become a mainstream application in academic literature and is broadly used for predictions, analysis, and evaluation of pharmacokinetic data. Significant progress has been made in developing advanced PBPK models that better capture human physiology, but oftentimes sufficient justification for the chosen model acceptance criterion and model structure is still missing. This Minireview provides a summary of the current landscape of PBPK applications used and highlights the need for advancing PBPK modeling science and training in academia.

Predictions of drug-drug interactions resulting from time-dependent inhibition (TDI) of CYP3A4 have consistently overestimated or mispredicted (ie, false positives) the interaction that is observed in vivo. Recent findings demonstrated that the presence of the allosteric modulator progesterone (PGS) in the in vitro assay could alter the in vitro kinetics of CYP3A4 TDI with inhibitors that interact with the heme moiety, such as metabolic-intermediate complex forming inhibitors. The impact of the presence of 100 μM PGS on the TDI of molecules in the class of macrolides typically associated with metabolic-intermediate complex formation was investigated. The presence of PGS resulted in varied responses across the inhibitors tested. The TDI signal was eliminated for 5 inhibitors, and unaltered in the case of 1, fidaxomicin. The remaining molecules erythromycin, clarithromycin, and troleandomycin were observed to have a decrease in both potency and maximum inactivation rate ranging from 1.7- to 6.7-fold. These changes in TDI kinetics led to a >90% decrease in inactivation efficiency. To determine in vitro conditions that could reproduce in vivo inhibition, varied concentrations of PGS were incubated with clarithromycin and erythromycin. The resulting in vitro TDI kinetics were incorporated into dynamic physiologically based pharmacokinetic models to predict clinically observed interactions. The results suggested that a concentration of ∼45 μM PGS would result in TDI kinetic values that could reproduce in vivo observations and could potentially improve predictions for CYP3A4 TDI. SIGNIFICANCE STATEMENT: The impact of the allosteric heterotropic modulator progesterone on the CYP3A4 time-dependent inhibition kinetics was quantified for a set of metabolic-intermediate complex forming mechanism-based inhibitors. We identify the in vitro conditions that optimally predict time-dependent inhibition for in vivo drug-drug interactions through dynamic physiologically based pharmacokinetic modeling. The optimized assay conditions improve in vitro to in vivo translation and prediction of time-dependent inhibition.

Evidence-based dose selection of drugs in pregnant women has been lacking because of challenges in studying maternal-fetal pharmacokinetics. Hence, many drugs are administered off-label during pregnancy based on data obtained from nonpregnant women. During pregnancy, drug transporters play an important role in drug disposition along with known gestational age-dependent changes in physiology and drug-metabolizing enzymes. In this review, as Dr Qingcheng Mao's former and current laboratory members, we summarize the collective contributions of Dr Mao, who lost his life to cancer, focusing on the role of drug transporters in drug disposition during pregnancy. Dr Mao and his team initiated their research by characterizing the structure of breast cancer resistance protein (ATP-binding cassette G2). Subsequently, they have made significant contributions to the understanding of the role of breast cancer resistance protein and other transporters, particularly P-glycoprotein (ATP-binding cassette B1), in the exposure of pregnant women and their fetuses to various drugs, including nitrofurantoin, glyburide, buprenorphine, bupropion, tetrahydrocannabinol, and their metabolites. This review also highlights the gestation- and pregnancy-dependent transporter expression at the blood-brain and blood-placenta barriers in mice. SIGNIFICANCE STATEMENT: Dr Qingcheng Mao and his team have made significant contributions to the investigation of the role of efflux transporters, especially P-glycoprotein and breast cancer resistance protein, in maternal-fetal exposure to many xenobiotics: nitrofurantoin, glyburide, buprenorphine, bupropion, tetrahydrocannabinol, and their metabolites. Studies of individual compounds and the expression of transporters during gestation and pregnancy have improved the understanding of maternal-fetal pharmacokinetics.

Several clinical studies have shown that COVID-19 increases the systemic concentration of drugs in hospitalized patients with COVID-19. However, it is unclear how COVID-19-mediated bidirectional dysregulation of hepatic and pulmonary cytochrome P450 (CYP) 3A4 affects drug concentrations, especially in the lung tissue, which is most affected by the disease. Herein, physiologically based pharmacokinetic modeling was used to demonstrate the differences in systemic and pulmonary concentrations of 4 respiratory infectious disease drugs when CYP3A4 is concurrently downregulated in the liver and upregulated in the lung based on existing clinical data on COVID-19-CYP3A4 interactions at varying severity levels including outpatients, non-intensive care unit (ICU), and ICU patients. The study showed that hepatic metabolism is the primary determinant of both systemic and pulmonary drug concentrations despite the concurrent bidirectional dysregulation of liver and lung CYP3A4. ICU patients had the most systemic and pulmonary drug exposure, with a percentage increase in the area under the concentration-time curve in the plasma compartment of approximately 44%, 56%, 114%, and 196% for clarithromycin, nirmatrelvir, dexamethasone, and itraconazole, respectively, relative to the healthy group. Within the ICU cohort, clarithromycin exhibited its highest exposure in lung tissue mass with a fold change of 1189, whereas nirmatrelvir and dexamethasone showed their highest exposure in the plasma compartment, with fold changes of about 126 and 5, respectively, compared with the maximum therapeutic concentrations for their target pathogens. Itraconazole was significantly underexposed in the lung fluid compartment, potentially explaining its limited efficacy for the treatment of COVID-19. These findings underscore the importance of optimizing dosing regimens in at risk ICU patients to enhance both efficacy and safety profiles. SIGNIFICANCE STATEMENT: This study investigated whether COVID-19-mediated concurrent hepatic downregulation and pulmonary upregulation of cytochrome P450 (CYP) 3A4 leads to differences in the systemic and pulmonary concentrations of 4 respiratory medicines. The study demonstrated that intercompartmental differences in drug concentrations were driven by only hepatic CYP3A4 expression. This work suggests that ICU patients with significant COVID-19-CYP3A4 interactions may be at risk of clinically relevant COVID-19-drug interactions, highlighting the need for optimizing dosing regimens in this patient group to improve safety and efficacy.

Remimazolam (Byfavo, Acacia Pharma), a recent Food and Drug Administration-approved ester-linked benzodiazepine, offers advantages in sedation, such as rapid onset and predictable duration, making it suitable for broad anesthesia applications. Its favorable pharmacological profile is primarily attributed to rapid hydrolysis, the primary metabolism pathway for its deactivation. Thus, understanding remimazolam hydrolysis determinants is essential for optimizing its clinical use. This study aimed to identify the enzyme(s) and tissue(s) responsible for remimazolam hydrolysis and to evaluate the influence of genetic polymorphisms and drug-drug interactions on its hydrolysis in the human liver. An initial incubation study with remimazolam and PBS, human serum, and the S9 fractions of human liver and intestine demonstrated that remimazolam was exclusively hydrolyzed by human liver S9 fractions. Subsequent incubation studies utilizing a carboxylesterase inhibitor (bis(4-nitrophenyl) phosphate), recombinant human carboxylesterase 1 (CES1) and carboxylesterase 2 confirmed that remimazolam is specifically hydrolyzed by CES1 in human liver. Furthermore, in vitro studies with wild-type CES1 and CES1 variants transfected cells revealed that certain genetic polymorphisms significantly impair remimazolam deactivation. Notably, the impact of CES1 G143E was verified using individual human liver samples. Moreover, our evaluation of the drug-drug interactions between remimazolam and several other substrates/inhibitors of CES1-including simvastatin, enalapril, clopidogrel, and sacubitril-found that clopidogrel significantly inhibited remimazolam hydrolysis at clinically relevant concentrations, with CES1 genetic variants potentially influencing the interactions. In summary, CES1 genetic variants and its interacting drugs are crucial factors contributing to interindividual variability in remimazolam hepatic hydrolysis, holding the potential to serve as biomarkers for optimizing remimazolam use. SIGNIFICANCE STATEMENT: This investigation demonstrates that remimazolam is deactivated by carboxylesterase 1 (CES1) in the human liver, with CES1 genetic variants and drug-drug interactions significantly influencing its metabolism. These findings emphasize the need to consider CES1 genetic variability and potential drug-drug interactions in remimazolam use, especially in personalized pharmacotherapy to achieve optimal anesthetic outcomes.

Environmentally persistent free radicals (EPFRs) are a recently recognized component of particulate matter that cause respiratory and cardiovascular toxicity. The mechanism of EPFR toxicity appears to be related to their ability to generate reactive oxygen species (ROS), causing oxidative damage. EPFRs were shown to affect cytochrome P450 (P450) function, inducing the expression of some forms through the Ah receptor. However, another characteristic of EPFRs is their ability to inhibit P450 activities. CYP2E1 is one of the P450s that is inhibited by EPFR (MCP230, the laboratory-generated EPFR made by heating silica 5% copper oxide, and silica [<0.2 μm in diameter] and 2-monochlorophenol at ≥230 °C) exposure. Because CYP2E1 is also known to generate ROS, it is important to understand the ability of EPFRs to influence the function of this enzyme and to identify the mechanisms involved. CYP2E1 was shown to be inhibited by EPFRs and to a lesser extent by non-EPFR particles. Because EPFR-mediated inhibition was more robust at subsaturating NADPH-P450 reductase (POR) concentrations, disruption of POR•CYP2E1 complex formation and electron transfer were examined. Surprisingly, neither complex formation nor electron transfer between POR and CYP2E1 was inhibited by EPFRs. Examination of ROS production showed that MCP230 generated a greater amount of ROS than the non-EPFR control particle (CuO-Si). When a POR/CYP2E1-containing reconstituted system was added to the pollutant-particle systems, there was a synergistic stimulation of ROS production. The results indicate that EPFRs cause inhibition of CYP2E1-mediated substrate metabolism, yet do not alter electron transfer and actually stimulate ROS generation. Taken together, the results are consistent with EPFRs affecting CYP2E1 function by inhibiting substrate metabolism and increasing the generation of ROS. SIGNIFICANCE STATEMENT: Environmentally persistent free radicals affect CYP2E1 function by inhibition of monooxygenase activity. This inhibition is not due to disruption of the POR•CYP2E1 complex or inhibition of electron transfer but due to the uncoupling of NADPH and oxygen consumption from substrate metabolism to the generation of reactive oxygen species. These results show that environmentally persistent free radicals block the metabolism of foreign compounds and synergistically stimulate the formation of reactive oxygen species that lead to oxidative damage within the organism.