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

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

Loganin Ameliorates Acute Kidney Injury and Restores Tofacitinib Metabolism in Rats: Implications for Renal Protection and Drug Interaction.

Tofacitinib, a Janus kinase (JAK) inhibitor used to treat rheumatoid arthritis, is metabolized through hepatic cytochrome P450 (CYP), specifically CYP3A1/2 and CYP2C11. Prolonged administration of rheumatoid arthritis medications is generally associated with an increased risk of renal toxicity. Loganin (LGN), an iridoid glycoside, has hepatorenal regenerative properties. This study investigates the potential of LGN to mitigate acute kidney injury (AKI) and its effects on the pharmacokinetics of tofacitinib in rats with cisplatin-induced AKI. Both intravenous and oral administration of tofacitinib to AKI rats significantly increased the area under the plasma concentration-time curve from time 0 to infinity (AUC) compared with control (CON) rats, an increase attributed to the decelerated non-renal clearance (CLNR) and renal clearance (CLR) of tofacitinib. Administration of LGN to AKI rats, however, protected kidneys from severe impairment, restoring the pharmacokinetic parameters (AUC, CLNR, and CLR) of tofacitinib to those observed in untreated CON rats, with partial recovery of kidney function, as evidenced by an increase in creatinine clearance (CLCR). Possible interactions between drugs and natural components should be considered, especially when co-administering both a drug and a natural extract containing LGN or iridoid glycosides to patients with kidney injury.

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

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

Association between CYP3A5 Gene Polymorphism and Post-Transplant Acute Immune Rejection in Renal Transplant Recipients Receiving Tacrolimus Therapy: A Correlation Study.

BACKGROUND: Acute immune rejection remains a challenge in the post-transplant period, with approximately 7.8% of renal transplant recipients experiencing rejection episodes within the first year. Genetic polymorphisms in the CYP3A5 gene, which influences tacrolimus metabolism, have garnered interest regarding their association with clinical outcomes in renal transplantation. METHODS: This retrospective correlation study analysed clinical data from kidney transplant patients who received tacrolimus treatment at our hospital from June 2015 to June 2023. The presence of CYP3A5 gene polymorphisms, tacrolimus trough levels, and demographic and clinical data were collected and analysed. RESULTS: A total of 105 kidney transplant patients were included. Patients were divided into acute immune rejection (n = 56) and non-acute immune rejection (n = 49) groups. The distribution of CYP3A5 gene polymorphisms differed significantly between the acute rejection and non-acute rejection groups (p = 0.037). The acute rejection group exhibited a higher frequency of CYP3A5 *1/*1 or *1/*3 genotypes than the non-acute rejection group. No statistically significant differences were found in the tacrolimus trough levels between the two groups. Correlation analysis revealed a statistically significant correlation between CYP3A5 gene polymorphism and post-transplant acute immune rejection (r = 0.223, p < 0.05). CONCLUSIONS: This study demonstrated a significant association between CYP3A5 gene polymorphism and the risk of post-transplant acute immune rejection in renal transplant recipients receiving tacrolimus therapy. These findings highlighted the importance of genetic variability in tacrolimus metabolism when managing immunosuppressive therapy in transplant recipients.

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

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

The Frequencies distribution of CYP3A5 rs776746 and ABCB1 rs1045642 polymorphisms in the west Algerian population and relationships with pharmacogenetics.

Introduction: Pharmacogenetic markers, such as the ATP Binding Cassette (ABCB1) and cytochrome P450 (CYP) 3A5 enzymes, play a crucial role in personalized medicine by influencing drug efficacy and toxicity based on individuals' or populations' genetic variations.This study aims to investigate the genetic polymorphisms of CYP3A5 (rs776746) and ABCB1 (rs1045642) in the West Algerian population and compare the genotypes and allelic distributions with those of various ethnic groups. Methods: The study involved 472 unrelated healthy subjects from the Western Algerian population. DNA genotyping was performed using TaqMan allelic discrimination assay. The variants in our population were compared to those in other ethnic groups available in the 1000 Genomes Project. Genotype and allele frequencies were calculated using the chi-square test and the Hardy-Weinberg equilibrium (HWE). Results: The minor allele frequencies were found to be 0.21 for CYP3A5 6986A and 0.34 for ABCB1 3435T. These frequencies were similar to those observed in North African populations, while notable differences were observed in comparison to certain Caucasian and African populations. Conclusion: The difference in the allelic and genotypic distribution of these polymorphisms emphasize the need for dose adjustments in drugs metabolized by CYP3A5 and transported by ABCB1 to optimize treatments outcomes.

Correlation of Genetic Polymorphism of CYP3A5 to Cyclophosphamide Efficacy and Toxicity in Rhabdomyosarcoma Pediatric Egyptian Cancer Patients.

OBJECTIVES: Rhabdomyosarcoma (RMS) accounts for 50% of soft tissue sarcomas and 7% of pediatric malignancies. Cyclophosphamide (CPA) is the cornerstone of therapy and is a prodrug that is activated by the highly polymorphic drug-metabolizing enzyme CYP3A5. We aim to examine the possible CYP3A5 polymorphism association with CPA efficacy, survival outcomes, and toxicity in Egyptian pediatric RMS patients. METHODS: The three non-functional SNPs, CYP3A5*3 rs776746 (C_26201809_30), CYP3A5*6 rs10264272 (C_30203950_10), and CYP3A5*7 rs41303343 (C_32287188_10) were genotyped by real-time PCR. We conducted a cohort retrospective study of 150 pediatric RMS patients treated with CPA-based first-line treatment to analyze the association between these genotypes and CPA efficacy/toxicities in RMS patients. KEY FINDINGS: The frequency of having normal, intermediate, and poor metabolizers was 4.7%, 34%, and 61.3%, respectively. There was an association between these different phenotypes, genotypes, and CPA efficacy/toxicity. Hemorrhagic cystitis and pancytopenia were present in all patients, while nephrotoxicity incidence was 87.3%. There was a notable difference in the occurrence of hemorrhagic cystitis among CYP3A5 intermediate metabolizers *1/*3, *1/*6, and poor metabolizers *3/*3, *3/*6 with a significance level of p<0.05. Neither CYP3A5*7 polymorphism nor *6/*6 genotype was identified in our study. CONCLUSION: Our results demonstrate that CYP3A5*3 (rs776746) and CYP3A5*6 (rs10264272) have a great association with CPA efficacy and toxicity in RMS patients.

Iminium ion metabolites are formed from nintedanib by human CYP3A4.

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

Effects of CYP3A4 genetic polymorphisms on the pharmacokinetics and efficacy of perampanel in Chinese pediatric patients with epilepsy.

OBJECTIVE: This study was the first to evaluate the effect of CYP3A4 gene polymorphisms on the plasma concentration and effectiveness of perampanel (PER) in Chinese pediatric patients with epilepsy. METHODS: We enrolled 102 patients for this investigation. The steady-state concentration was determined after patients maintained a consistent PER dosing regimen for at least 21 days. Plasma PER concentrations were measured using liquid chromatography-tandem mass spectrometry. Leftover samples from standard therapeutic drug monitoring were allocated for genotyping analysis. The primary measure of efficacy was the rate of seizure reduction with PER treatment at the final check-up. RESULTS: The CYP3A4×10 GC phenotype exhibited the highest average plasma concentration of PER at 491.1 ±â€¯328.1 ng/mL, in contrast to the CC phenotype at 334.0 ±â€¯161.1 ng/mL. The incidence of adverse events was most prominent in the CYP3A4×1 G TT and CYP3A4×10 GC groups, with rates of 77.8 % (7 of 9 patients) and 50.0 % (46 of 92 patients), respectively. Moreover, the percentage of patients for whom PER was deemed ineffective was least in the CYP3A4×1 G TT and CYP3A4×10 CC groups, recorded at 11.1 % (1 of 9 patients) and 10.0 % (1 of 10 patients), respectively. There was a significant correlation between PER plasma concentration and either exposure or toxicity (both with p < 0.05). We suggest a plasma concentration range of 625-900 ng/mL as a suitable reference for PER in Chinese patients with epilepsy. CONCLUSION: The CYP3A4×10 gene's genetic polymorphisms influence plasma concentrations of PER in Chinese pediatric patients with epilepsy. Given that both efficacy and potential toxicity are closely tied to plasma PER levels, the CYP3A4 genetic phenotype should be factored in when prescribing PER to patients with epilepsy.

Study on Cytochrome P450 Metabolic Profile of Paclitaxel on Rats using QTOF-MS.

BACKGROUND: Paclitaxel (PTX) is a key drug used for chemotherapy for various cancers. The hy-droxylation metabolites of paclitaxel are different between humans and rats. Currently, there is little infor-mation available on the metabolic profiles of CYP450 enzymes in rats. OBJECTIVE: This study evaluated the dynamic metabolic profiles of PTX and its metabolites in rats and in vitro. METHODS: Ultra-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrome-try (UHPLC-Q-TOF-MS) and LC-MS/MS were applied to qualitative and quantitative analysis of PTX and its metabolites in rats' liver microsomes and recombinant enzyme CYP3A1/3A2. Ten specific inhibitors [NF (CYP1A1), FFL (CYP1A2), MOP (CYP2A6), OND (CYP2B6), QCT (CYP2C8), SFP (CYP2C9), NKT (CYP2C19), QND (CYP2D6), MPZ (CYP2E1) and KTZ (CYP3A4)] were used to identify the metabolic pathway in vitro. RESULTS: Four main hydroxylated metabolites of PTX were identified. Among them, 3'-p-OH PTX and 2-OH PTX were monohydroxylated metabolites identified in rats and liver microsome samples, and 6α-2-di-OH PTX and 6α-5"-di-OH PTX were dihydroxylated metabolites identified in rats. CYP3A recombinant enzyme studies showed that the CYP3A1/3A2 in rat liver microsomes was mainly responsible for metabolizing PTX into 3'-p-OH-PTX and 2-OH-PTX. However, 6α-OH PTX was not detected in rat plasma and liver microsome samples. CONCLUSION: The results indicated that the CYP3A1/3A2 enzyme, metabolizing PTX into 3'-p-OH-PTX and 2-OH-PTX, is responsible for the metabolic of PTX in rats. The CYP2C8 metabolite 6α-OH PTX in humans was not detected in rat plasma in this study, which might account for the interspecies metabolic differences between rats and humans. This study will provide evidence for drug-drug interaction research in rats.

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

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

An open-label study to explore the optimal design of CYP3A drug-drug interaction clinical trials in healthy Chinese people.

A drug-drug interaction (DDI) trial of cytochrome P450 3A (CYP3A) is a necessary part of early-phase trials of drugs mainly metabolized by this enzyme, but CYP3A DDI clinical trials do not have a standard design, especially for Chinese people. We aimed to offer specific recommendations for CYP3A DDI clinical trial design. This was an open, three-cycle, self-controlled study. Healthy subjects were given different administration strategies of CYP3A4 perpetrators. In each cycle, blood samples were collected before and within 24 h after the administration of midazolam, the CYP3A indicator substrate. The plasma concentrations of midazolam and 1-hydroxymidazolam was obtained using liquid chromatography tandem mass spectrometry assay. For CYP3A inhibition, itraconazole exposure with a loading dose could increase the exposure of midazolam by 3.21-fold based on maximum plasma concentration (Cmax), 8.37-fold based on area under the curve Pharmacology Research & Perspectives for review only from zero to the time point (AUC0-t), and 11.22-fold based on area under the curve from zero to infinity (AUC0-∞). The data were similar for itraconazole pretreatment without a loading dose. For CYP3A induction, the exposure of rifampin for 7 days decreased the plasma concentration of midazolam ~0.27-fold based on Cmax, ~0.18-fold based on AUC0-t, and ~0.18-fold based on AUC0-∞. Midazolam exposure did not significantly change when the pretreatment of rifampin increased to 14 days. This study showed that itraconazole pretreatment for 3 days without a loading dose was enough for CYP3A inhibition, and pretreatment with rifampin for 7 days could induce near-maximal CYP3A levels.

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

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

Functional assessment of CYP3A4 and CYP2C19 genetic polymorphisms on the metabolism of clothianidin invitro.

Clothianidin, classified as a second-generation neonicotinoid, has achieved extensive application due to its high efficacy against insect pests. This broad-spectrum usage has resulted in its frequent detection in environmental surveys. CYP2C19 and CYP3A4 are crucial for converting clothianidin to desmethyl-clothianidin (dm-clothianidin). The expression of these CYP450s can be significantly influenced by genetic polymorphisms. The objective of our research was to examine the catalytic effects of 27 CYP3A4 variants and 31 CYP2C19 variants on the metabolism of clothianidin within recombinant insect microsomes. These variants were assessed through a well-established incubation procedure. In addition, the concentration of its metabolite dm-clothianidin was quantified by employing an ultra performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS). Lastly, the kinetic parameters of these CYP3A4 and CYP2C19 variants were calculated by applying Michaelis-Menten kinetic analysis to fit the data. The observed changes in enzyme activity were related to the metabolic transformation of clothianidin to dm-clothianidin. In the CYP2C19 metabolic pathway, one variant (CYP2C19.23) showed no notable change in intrinsic clearance (CLint), four variants (CYP2C19.29, .30, .31 and L16F) demonstrated a marked increase in CLint (110.86-183.46 %), and the remaining 25 variants exhibited a considerable decrease in CLint (26.38-89.79 %), with a maximum decrease of 73.62 % (CYP2C19.6). In the CYP3A4 metabolic pathway, 26 variants demonstrated significantly reduced CLint (10.54-52.52 %), with a maximum decrease of 89.46 % (CYP3A4.20). Our results suggested that most variants of CYP3A4 and CYP2C19 significantly altered the enzymatic activities associated with clothianidin metabolism to various degrees. This study provides new insights into assessing the metabolic behavior of pesticides and delivers crucial data that can guide clinical detoxification strategies.

Role of Cytochrome P450 3A4 in Cancer Drug Resistance: Challenges and Opportunities.

One of the biggest obstacles to the treatment of diseases, particularly serious conditions like cancer, is therapeutic resistance. The process of drug resistance is influenced by a number of important variables, including MDR genes, drug efflux, low-quality medications, inadequate dosage, etc. Drug resistance must be addressed, and new combinations based on the pharmacokinetics/pharmacodynamics (PK-PD) characteristics of the partner pharmaceuticals must be developed in order to extend the half-lives of already available medications. The primary mechanism of drug elimination is hepatic biotransformation of medicines by cytochrome P450 (CYP) enzymes; of these CYPs, CYP3A4 makes up 30-40% of all known cytochromes that metabolize medications. Induction or inhibition of CYP3A4-mediated metabolism affects the pharmacokinetics of most anticancer drugs, but these details are not fully understood and highlighted because of the complexity of tumor microenvironments and various influencing patient related factors. The involvement of CYPs, particularly CYP3A4 and other drug-metabolizing enzymes, in cancer medication resistance will be covered in the current review.

1ß-Hydroxydeoxycholic Acid as an Endogenous Biomarker in Human Plasma for Assessment of CYP3A Clinical Drug-Drug Interaction Potential.

4ß-Hydroxycholesterol (4ß-HC) in plasma has been used as a biomarker to assess CYP3A drug-drug interaction (DDI) potential during drug development. However, due to the long half-life and narrow dynamic range of 4ß-HC, its use has been limited to the identification of CYP3A inducers, but not CYP3A inhibitors. The formation of 1ß-hydroxydeoxycholic acid (1ß-OH DCA) from deoxycholic acid (DCA) is mediated by CYP3A, thus 1ß-OH DCA can potentially serve as an alternative to 4ß-HC for assessment of CYP3A DDI potential. To study this feasibility, we developed a sensitive LC-MS/MS method for the simultaneous quantitation of 1ß-OH DCA and its glycine and taurine conjugates in human plasma with the LLOQ of 50 pg/mL, which enabled the quantitation of basal levels and further reduction. The method was applied to a DDI study to assess how 1ß-OH DCA and its glycine and taurine conjugates would respond to CYP3A induction or inhibition. Rifampin induction resulted in an increase of 1ß-OH DCA and its conjugates in plasma, with 6.8-, 7.8-, 8.3-, 10.3-fold increases of AUCLST, AUC24h, Cmax and mean concentrations for total 1ß-OH DCA (total of all three forms), respectively. Importantly, inhibition with itraconazole resulted in notable reduction of these biomarkers, with 84%, 85%, 82%, 81% reductions of AUCLST, AUC24h, Cmax and mean concentrations for total 1ß-OH DCA, respectively. This preliminary data demonstrates for the first time that total 1ß-OH DCA in plasma has the potential to serve as a biomarker for CYP3A DDI assessment in early clinical development and may provide key advantages over 4ß-HC. Significance Statement We have reported the use of total 1ß-Hydroxydeoxycholic Acid (1ß-OH DCA) (sum of 1ß-OH DCA and its glycine and taurine conjugates) plasma concentration as a biomarker for CYP3A activity. Itraconazole inhibition led to an 81-85% decrease of total 1ß-OH DCA plasma exposures, while rifampin induction led to a 6.8-10.3 fold increase of total 1ß-OH DCA plasma exposures. Using 1ß-OH DCA exposures in plasma also provides benefit of allowing PK and biomarker assessment using the same matrix, thus simplify collection procedures.

Steroid-tacrolimus drug-drug interaction and the effect of CYP3A genotypes.

AIMS: Tacrolimus, metabolized by CYP3A4 and CYP3A5 enzymes, is susceptible to drug-drug interactions (DDI). Steroids induce CYP3A genes to increase tacrolimus clearance, but the effect is variable. We hypothesized that the extent of the steroid-tacrolimus DDI differs by CYP3A4/5 genotypes. METHODS: Kidney transplant recipients (n = 2462) were classified by the number of loss of function alleles (LOF) (CYP3A5*3, *6 and *7 and CYP3A4*22) and steroid use at each tacrolimus trough in the first 6 months post-transplant. A population pharmacokinetic analysis was performed by nonlinear mixed-effect modelling (NONMEM) and stepwise covariate modelling to define significant covariates affecting tacrolimus clearance. A stochastic simulation was performed and translated into a Shiny application with the mrgsolve and Shiny packages in R. RESULTS: Steroids were associated with modestly higher (3%-11.8%) tacrolimus clearance. Patients with 0-LOF alleles receiving steroids showed the greatest increase (11.8%) in clearance compared to no steroids, whereas those with 2-LOFs had a negligible increase (2.6%) in the presence of steroids. Steroid use increased tacrolimus clearance by 5% and 10.3% in patients with 1-LOF and 3/4-LOFs, respectively. CONCLUSIONS: Steroids increase the clearance of tacrolimus but vary slightly by CYP3A genotype. This is important in individuals of African ancestry who are more likely to carry no LOF alleles, may more commonly receive steroid treatment, and will need higher tacrolimus doses.

Quantitative prediction of CYP3A induction-mediated drug-drug interactions in clinical practice.

There have been no reports on the quantitative prediction of CYP3A induction-mediated decreases in AUC and Cmax for drug candidates identified as a "victims" of CYP3A induction. Our previous study separately evaluated the fold-induction of hepatic and intestinal CYP3A by known inducers using clinical induction data and revealed that we were able to quantitatively predict the AUC ratio (AUCR) of a few CYP3A substrates in the presence and absence of CYP3A inducers. In the present study, we investigate the predictability of AUCR and also Cmax ratio (CmaxR) in additional 54 clinical studies. The fraction metabolized by CYP3A (fm), the intestinal bioavailability (Fg), and the hepatic intrinsic clearance (CLint) of substrates were determined by the in vitro experiments as well as clinical data used for calculating AUCR and CmaxR. The result showed that 65-69% and 65-67% of predictions were within 2-fold of observed AUCR and CmaxR, respectively. A simulation using multiple parameter combinations suggested that the variability of fm and Fg within a certain range might have a minimal impact on the calculation output. These findings suggest that clinical AUCR and CmaxR of CYP3A substrates can be quantitatively predicted from the preclinical stage.

Effect of Erdafitinib on the Pharmacokinetics of Midazolam and Metformin in Patients With Advanced Solid Tumors Harboring FGFR Gene Alterations.

Erdafitinib, an oral pan-FGFR inhibitor, is used in locally advanced or metastatic urothelial carcinoma for adults with FGFR3 genetic alterations and whose disease progressed following prior systemic therapy. This drug-drug interaction substudy evaluated the effect of erdafitinib on the pharmacokinetics of midazolam (cytochrome P450 3A4 substrate), and metformin (organic cation transporter 2 substrate). Twenty-five patients with advanced solid tumors harboring FGFR gene alterations received pretreatment with single doses of midazolam and metformin, followed by a daily dose of erdafitinib. Drug-drug interaction assessments were performed at erdafitinib steady state following coadministration of single doses of midazolam and metformin, respectively. Geometric mean ratios for maximum plasma concentration and area under the plasma concentration-time curve (AUC) from time 0 to the last measurable concentration, and AUC from time 0 to infinity were estimated using linear mixed-effects models (90% confidence interval within 80%-125% indicated no interaction). The 90% confidence intervals of geometric mean ratios for maximum plasma concentration, AUC from time 0 to the last measurable concentration, and AUC from time 0 to infinity of midazolam (86.3%, 88.5%, and 82.1%), 1-OH midazolam (99.8%, 97.4%, and 101.5%), and metformin (108.7%, 119.0%, and 113.9%) were either contained or slightly outside the 80%-125% interval and not considered clinically meaningful. Adverse events were consistent with the known erdafitinib safety profile; no new safety signals emerged. Thus, repeated dosing of erdafitinib had no clinically meaningful effect on the pharmacokinetics of midazolam or metformin.

Concomitant use of calcitonin gene-related peptide (CGRP) antagonists with azole antifungals in patients with hematological malignancies.

OBJECTIVE: Small molecule calcitonin gene-related peptide (CGRP) antagonists such as rimegepant, ubrogepant, and atogepant have been approved for migraine treatment and/or prevention. These molecules are metabolized by cytochrome P-450 3A4 (CYP3A4) enzymes in vivo, hence they are contraindicated or recommended to be avoided in combination with strong/moderate CYP3A4 inhibitors, namely posaconazole (strong) and isavuconazonium (moderate). However, no literature has been published on the impact this interaction has on patient safety and tolerability. In this case series, we report five cases in which CGRP antagonists and azole antifungal therapy were given concurrently, to provide real-world outcomes of this interaction. DATA SOURCES: Electronic medical records at our hospital system were reviewed between January 2021 and December 2023 to find patients who met the criteria of hematological malignancy, taking CGRP-antagonist and azole antifungal therapy. Records were then further investigated to find cases where CGRP antagonists and azole antifungals were used concomitantly. DATA SUMMARY: Concurrent use of CGRP antagonists and azole antifungal therapy was feasible for patients with migraines and hematological malignancies. None of the patients experienced any grade 3 or higher non-hematological toxicity from the proposed over-exposure to CGRP antagonist. The combination was well tolerated without any need for therapy discontinuation or dose modifications. CONCLUSIONS: It is recommended to follow the manufacturers' guidance on drug interactions, however, in the setting where there are no other options, concomitant use of CGRP antagonists with azole antifungals is possible with monitoring and observation for adverse effects.