Differences In Drug Metabolism Research Articles

Italian Association of Hospital Cardiologists Position Paper 'Gender discrepancy: time to implement gender-based clinical management'.

It has been well assessed that women have been widely under-represented in cardiovascular clinical trials. Moreover, a significant discrepancy in pharmacological and interventional strategies has been reported. Therefore, poor outcomes and more significant mortality have been shown in many diseases. Pharmacokinetic and pharmacodynamic differences in drug metabolism have also been described so that effectiveness could be different according to sex. However, awareness about the gender gap remains too scarce. Consequently, gender-specific guidelines are lacking, and the need for a sex-specific approach has become more evident in the last few years. This paper aims to evaluate different therapeutic approaches to managing the most common women's diseases.

Therapeutic Drug Monitoring in Psychiatry: Enhancing Treatment Precision and Patient Outcomes.

Psychiatric disorders often require pharmacological interventions to alleviate symptoms and improve quality of life. However, achieving an optimal therapeutic outcome is challenging due to several factors, including variability in the individual response, inter-individual differences in drug metabolism, and drug interactions in polytherapy. Therapeutic drug monitoring (TDM), by measuring drug concentrations in biological samples, represents a valuable tool to address these challenges, by tailoring medication regimens to each individual. This review analyzes the current landscape of TDM in psychiatric practice, highlighting its significance in optimizing drug dosages, minimizing adverse effects, and improving therapeutic efficacy. The metabolism of psychiatric medications (i.e., mood stabilizers, antipsychotics, antidepressants) often exhibits significant inter-patient variability. TDM can help address this variability by enhancing treatment personalization, facilitating early suboptimal- or toxic-level detection, and allowing for timely interventions to prevent treatment failure or adverse effects. Furthermore, this review briefly discusses technological advancements and analytical methods supporting the implementation of TDM in psychiatric settings. These innovations enable quick and cost-effective drug concentration measurements, fostering the widespread adoption of TDM as a routine practice in psychiatric care. In conclusion, the integration of TDM in psychiatry can improve treatment outcomes by individualizing medication regimens within the so-called precision medicine.

Anti-Emetics in Children Receiving Chemotherapy for Solid Tumors and Leukemia: Pharmacology and Optimization of Therapy for Nausea and Vomiting.

The management of chemotherapy-induced nausea and vomiting (CINV) in children remains challenging due to differences in the chemotherapy regimens, their relative emetogenicity compared to that in adults and differences in drug metabolism and the available formulations. The common four classes of anti-emetics used for the treatment and prophylaxis of CINV in children include dexamethasone, neurokinin-1 receptor antagonists, 5-hydroxytryptamine-3 receptor antagonists (5HT3RAs), and olanzapine. The appropriate dose of dexamethasone for CINV prophylaxis in children is unknown, with a significant variability in dosage ranging between 6 and 32 mg/m2/day. The dose of dexamethasone is decreased by 30% when this drug is combined with (fos)aprepitant in children, in contrast to a decrease of 50% required in adults. The use of aprepitant in younger children (<12 years) is often hampered by the non-availability of oral suspension formulations in many countries; alternatively, 80 mg capsules are administered for 1-3 days in certain institutes to children weighing between 15 and 40 kg. Among the different 5HT3RAs, palonosetron is comparatively metabolized faster in children than in adults, requiring a higher dosage for similar efficacy to that achieved in adults. Olanzapine is a newer agent, used in doses between 0.1 and 0.14 mg/kg/day in children, with good anti-emetic efficacy, but has sedation and hyperglycemia as concerning adverse effects. Drug interactions between anti-emetics and between anti-emetics and chemotherapy/supportive agents (azole antifungals, cyclosporine, arsenic trioxide), especially QTc prolongation, should be considered during prescription.

Association of Valproic Acid and Its Main Metabolites' Plasma Concentrations with Clinical Outcomes among Epilepsy Patients: A 10-Year Retrospective Study Based on Therapeutic Drug Monitoring.

Valproic acid (VPA) is a first-line antiepileptic drug with broad efficacy. Due to significant individual differences in its metabolism, therapeutic drug monitoring is commonly used. However, the recommended therapeutic range (50-100 μg/mL) is inadequate for predicting clinical outcomes. Additionally, the relationship between VPA metabolites and clinical outcomes remains unclear. In this retrospective study, 485 Chinese Southern Han epilepsy patients receiving VPA monotherapy were analyzed after reaching steady-state levels. Plasma concentrations of VPA and its five main metabolites were determined by liquid chromatography-mass spectrometry (LC-MS). We assessed the relevance of the recommended therapeutic VPA range for clinical outcomes and explored the association between VPA/metabolites levels and treatment efficacy/adverse effects. Vitro experiments were conducted to assess 4-ene-VPA hepatotoxicity. The therapeutic range of VPA exhibited no significant correlation with clinical outcomes, and plasma concentrations of VPA failed to serve as predictive indicators for treatment response/adverse effects. Treatment responders had higher 2-PGA concentrations (median, 26.39 ng/mL versus 13.68 ng/mL), with a threshold of 36.5 ng/mL for optimal epilepsy treatment. Patients with abnormal liver function had a higher 4-ene-VPA median concentration (6.41 μg/mL versus 4.83 μg/mL), and the ratio of 4-ene-VPA to VPA better predicted VPA-induced hepatotoxicity (area under the curve, 0.718) than 4-ene-VPA concentration. Vitro experiments revealed that 4-ene-VPA was more hepatotoxic than VPA in HepaRG and L02 cell lines. Total plasma VPA concentration does not serve as a predictor of clinical outcomes. 2-PGA concentrations may be associated with efficacy, whereas the ratio of 4-ene-VPA to VPA may be considered a better biomarker (threshold 10.03%) for VPA-induced hepatotoxicity. SIGNIFICANCE STATEMENT: This was the first and largest observational cohort in China to explore the relationship between patients' parent and metabolites concentrations of VPA and clinical outcomes during the maintenance of VPA monotherapy in epileptic patients. This study provided feasible references of VPA for epilepsy clinical treatment with a larger sample of patients compared with previous studies for a more definitive conclusion based on real-world situations. We found two potential biomarkers in predicting efficacy and liver injury, respectively. This breakthrough has the potential to assist in the rational use of VPA.

Differential Effects of Clotrimazole on X-Ray Crystal Structures of Human Cytochromes P450 3A5 and 3A4.

Cytochromes P450 CYP3A5 and CYP3A4 exhibit differential plasticity that underlies differences in drug metabolism and drug-drug interactions. To extend previous studies, CYP3A4 and CYP3A5 were cocrystallized with clotrimazole, a compact ligand that binds to the heme iron in the catalytic center of the active site. Binding studies indicate that clotrimazole exhibits tight binding to CYP3A5 with a binding affinity (Kd) of <0.01 μM like that of CYP3A4. A single clotrimazole is bound to the heme iron in CYP3A4 that triggers expansion of active site cavity that reflects a loss of aromatic interactions between phenylalanine sidechains in the distal active site and increased conformational entropy for the F-F' connector due to reorientation of Phe-304 to accommodate clotrimazole. In contrast to CYP3A4, the CYP3A5 Phe-304 exhibits an induced fit along with Phe-213 to form edge-to-face aromatic interactions with heme-bound clotrimazole. These aromatic interactions between aromatic amino acids propagate by induced fits with a second clotrimazole residing in the distal active site and a third clotrimazole bound in an expanded entrance channel as well as between the three clotrimazoles. The large, expanded entrance channel surrounded by the C-terminal loop and the F' and A' helices in CYP3A5 suggests conformational selection for the binding of clotrimazole due to its large girth, which may also cause the entrance channel to remain open after the binding of the first clotrimazole to the heme iron. The additional binding sites suggest a path for sequential binding of one molecule to reach and bind to the heme iron. SIGNIFICANCE STATEMENT: Clotrimazole binds to the heme iron of CYP3A5 and CYP3A4. In CYP3A5, two clotrimazoles also bind in the distal active site and in an expanded entrance channel. Aromatic interactions between clotrimazoles and phenylalanine sidechains including Phe-304 indicate induced fits for each clotrimazole. In contrast to CYP3A5, displacement of the CYP3A4 Phe-304 rotamer by clotrimazole leads to extensive disruption of phenylalanine interactions that limit the space above the heme, to an expanded active site cavity, and to increased CYP3A4 conformational heterogeneity.

Functional evaluation of CYP2C19 and CYP3A4 gene polymorphism on ibuprofen metabolism

AimIbuprofen is the most commonly used analgesic. CYP polymorphisms are mainly responsible for the differences in drug metabolism among individuals. Variations in the ability of populations to metabolize ibuprofen can lead to drug exposure events. The aim of this study was to evaluate the effects of CYP2C19 and CYP3A4 polymorphisms on ibuprofen metabolism in a Chinese population. MethodsFirst, 31 CYP2C19 and 12 CYP3A4 microsomal enzymes were identified using an insect expression system. Then, variants were evaluated using a mature incubation system. Moreover, ibuprofen metabolite content was determined via ultra-performance liquid chromatography-tandem mass spectrometry analysis. Finally, kinetic parameters of CYP2C19 and CYP3A4 genotypes were determined via Michaelis-Menten curve fitting. ResultsMost variants exhibited significantly altered intrinsic clearance compared to the wild type. In the CYP2C19 metabolic pathway, seven variants exhibited no significant alterations in intrinsic clearance (CLint), six variants exhibited significantly high CLint (121–291%), and the remaining 15 variants exhibited substantially reduced CLint (1–71%). In the CYP3A4 metabolic pathway, CYP3A4*30 was not detected in the metabolite content due to the absence of activity, and 10 variants exhibited significantly reduced CLint. ConclusionTo the best of our knowledge, this is the first study to assess the kinetic characteristics of 31 CYP2C19 and 12 CYP3A4 genotypes on ibuprofen metabolism. However, further studies are needed on poor metabolizers as they are more susceptible to drug exposure. Our findings suggest that the kinetic characteristics in combination with artificial intelligence to predict the toxicity of ibuprofen and reduce any adverse drug reactions.

Mortality rate and social disparity trends with tyrosine kinase inhibitory availability in chronic myelogenous leukemia: An analysis in the US from 1999 to 2020.

7055 Background: We analyzed CML mortality from 1999 to 2020 in the US in relation to FDA approval of tyrosine kinase inhibitors (TKIs). These agents were introduced in the 2000s, revolutionizing the treatment of CML and providing a paradigm for targeted therapy in oncology. Starting with imatinib in 2001, followed by dasatinib (2006), nilotinib (2007), and bosutinib (2012). TKIs have increased tolerability and efficacy for the treatment of CML as compared to previous treatment modalities. We investigated age-adjusted mortality rates (AAMR) and annual percent change (APC) in this population in relation to TKI approval. Methods: Using the CDC WONDER database, we examined mortality trends from 1999 to 2020 for CML in the US. AAMRs were calculated per 100,000 people and stratified by sex, race/ethnicity, and census region. AAMR groups were listed as pre-TKI era and 1 year post-FDA approval of different TKI agents. We computed the APC trends for the respective stratification with Joinpoint, a regression analysis program. Results: Between 1999 and 2020 there were 35,268 deaths from CML. In 1999, overall AAMR initially was 0.8, which improved to 0.5 by 2020 with a respective APC of -2.5%. In our subgroup analysis there was a consistent and significant decrease in AAMR since the introduction of Imatinib in 2001. With additional TKI releases, AAMR continued to decline in all subgroups. APC for mortality rates was similar between all subgroups [-2.0 to -2.8%] indicating a similar benefit regardless of subgroup. Male AAMR was consistently higher than female AAMR. Black and white patients (0.5, 2020) have a 2.5x higher AAMR (0.2, 2020) compared to Asian patients. Census region did not show a significant difference between each other. Conclusions: Since the FDA approval of imatinib in 2001 and the subsequent release of TKIs there has been a significant impact on reducing AAMR for patients with CML. The decline was seen in sex, race, and census region. The APCs were similar between all subgroups indicating a consistent improvement in survival. Possible etiologies of disparities in AARM for males in comparison to females and for black and white patients in comparison to Asian patients include gender and race-associated gene polymorphisms possibly inducing differences in drug metabolism. Further gender and race specific pharmacokinetic studies would be useful to further elucidate etiology of the disparity and may lead to changes in TKI dosing strategies. [Table: see text]

Improving the predictive power of xenograft and syngeneic anti-tumour studies using mice humanised for pathways of drug metabolism

Drug development is an expensive and time-consuming process, with only a small fraction of drugs gaining regulatory approval from the often many thousands of candidates identified during target validation. Once a lead compound has been identified and optimised, they are subject to intensive pre-clinical research to determine their pharmacodynamic, pharmacokinetic and toxicological properties, procedures which inevitably involve significant numbers of animals - mainly mice and rats, but also dogs and monkeys in much smaller numbers and for specific types of drug candidates. Many compounds that emerge from this process, having been shown to be safe and efficacious in pre-clinical studies, subsequently fail to replicate this outcome in clinical trials, therefore wasting time, money and, most importantly, animals. Due to high rates of metabolism and a differing spectrum of metabolites (some pharmacologically active) in rodents, species differences in drug metabolism can be a major impediment to drug discovery programmes and confound theextrapolation of animal data to humans. To circumvent this, we have developed a complex transgenic mouse model - 8HUM - which faithfully replicates human Phase I drug metabolism (and its regulation), and which will generate more human-relevant data from fewer animals in a pre-clinical setting and reduce attrition in the clinic. One key area for the pre-clinical application of animals in an oncology setting - almost exclusively mice - is their use in anti-tumour studies. We now further demonstrate the utility of the 8HUM mouse using a murine melanoma cell line as a syngeneic tumour and also present an immunodeficient version 8HUM_Rag2 -/- - for use in xenograft studies. These models will be of significant benefit not only to Pharma for pre-clinical drug development work, but also throughout the drug efficacy, toxicology, pharmacology, and drug metabolism communities, where fewer animals will be needed to generate more human-relevant data.

Quantitative Characterization of Clinically Relevant Drug-Metabolizing Enzymes and Transporters in Rat Liver and Intestinal Segments for Applications in PBPK Modeling.

Rats are extensively used as a preclinical model for assessing drug pharmacokinetics (PK) and tissue distribution; however, successful translation of the rat data requires information on the differences in drug metabolism and transport mechanisms between rats and humans. To partly fill this knowledge gap, we quantified clinically relevant drug-metabolizing enzymes and transporters (DMETs) in the liver and different intestinal segments of Sprague-Dawley rats. The levels of DMET proteins in rats were quantified using the global proteomics-based total protein approach (TPA) and targeted proteomics. The abundance of the major DMET proteins was largely comparable using quantitative global and targeted proteomics. However, global proteomics-based TPA was able to detect and quantify a comprehensive list of 66 DMET proteins in the liver and 37 DMET proteins in the intestinal segments of SD rats without the need for peptide standards. Cytochrome P450 (Cyp) and UDP-glycosyltransferase (Ugt) enzymes were mainly detected in the liver with the abundance ranging from 8 to 6502 and 74 to 2558 pmol/g tissue. P-gp abundance was higher in the intestine (124.1 pmol/g) as compared to that in the liver (26.6 pmol/g) using the targeted analysis. Breast cancer resistance protein (Bcrp) was most abundant in the intestinal segments, whereas organic anion transporting polypeptides (Oatp) 1a1, 1a4, 1b2, and 2a1 and multidrug resistance proteins (Mrp) 2 and 6 were predominantly detected in the liver. To demonstrate the utility of these data, we modeled digoxin PK by integrating protein abundance of P-gp and Cyp3a2 into a physiologically based PK (PBPK) model constructed using PK-Sim software. The model was able to reliably predict the systemic as well as tissue concentrations of digoxin in rats. These findings suggest that proteomics-informed PBPK models in preclinical species can allow mechanistic PK predictions in animal models including tissue drug concentrations.

UPLC–MS/MS-Based Targeted Proteomics Assay to Evaluate the Relationship between CYP3A2 Expression and Enzymatic Activity

Traditional analytical methods such as western blotting and reverse transcription-polymerase chain reaction only allow semiquantitative assessments and cannot accurately quantify the expression of the cytochrome P450 (CYP) enzyme. Therefore, the relationship between excess CYP enzyme and enzymatic activity is not been systematically studied yet. In the present study, we developed a new method using ultra-high-performance liquid chromatography (UPLC) mass spectroscopy (MS)/MS and determined the accurate quantification of CYP3A2 in rat liver. The linear range was 0.1329–8.508 ng/mL. The intra- and interday precisions and accuracies data fulfilled the acceptance criteria of food and drug association guidelines for bio analytical method validation. We compared the quantitative results with CYP3A2 activity obtained by the cocktail assay. The developed method was successfully used for the quantitative analysis of CYP3A2. It provided a good background for determining the differences in drug metabolism caused by different CYP expression. Keywords: UPLC-MS/MS; CYP3A2; Accurate Quantitation; Enzyme Activity

Early Donor T-Cell Engraftment Is Critical for Immune Tolerance in Reduced Intensity Haploidentical Bone Marrow Transplant with Post-Transplant Cyclophosphamide for Sickle Cell Disease: Vanderbilt Global Haploidentical Transplant Learning Collaborative (VGC2)

Introduction: Global application of bone marrow transplant (BMT) for sickle cell disease (SCD) requires a protocol that addresses the core limitations of this approach - namely donor availability, graft-versus-host disease (GVHD) and engraftment. To meet these demands, we developed the Vanderbilt Haploidentical Learning Collaborative across 10 countries and 22 sites with a common related HLA-haploidentical (haploBMT) reduced intensity platform. Our phase II trial (ClinicalTrials.gov identifier NCT01850108) was successfully employed with a probability of overall survival of 96.7% (95% CI 87.1- 99.2%) at one year, but a high rate of graft failure (GF) in pediatric patients (<18 years), prompting us to perform an in-depth analysis of engraftment kinetics. Methods: Seven Institutional Review Board approved sites enrolled patients undergoing a haploBMT for SCD from 8/14/2014-2/28/2022. Common conditioning included: thymoglobulin 4.5 mg/kg, thiotepa 10 mg/kg, fludarabine 150 mg/m2, cyclophosphamide 29 mg/kg and TBI 2Gy. GVHD prophylaxis included post-transplant cyclophosphamide 100 mg/kg, mycophenolate mofetil, and sirolimus (de la Fuente et al. BBMT 2019). Hydroxyurea and hypertransfusion to lower the percentage hemoglobin S <30% for at least 60 days pre-conditioning was variably employed. Primary GF was defined as <5% donor myeloid/lymphoid or whole blood (WB) chimerism at one-month (M1) post-haploBMT. Secondary GF was defined <5% donor myeloid/lymphoid or WB chimerism with prior documentation of >5% donor cells at M1. Categorical variables were compared using Fisher's exact test. Continuous variables were compared using Wilcoxon rank sum test. Results: A total of 41 pediatric and 39 adult subjects were enrolled for data analysis. GF was only noted in the pediatric cohort with 4 (10%) and 6 (15%) developing primary and secondary GF, respectively. Primary GF was associated with lack of a hypertransfusion pre-conditioning (0% vs 54%) and CMV reactivation (75% vs 21%) compared to engrafted patients. For secondary GF, we evaluated the mechanisms of prolonged tolerance including early donor T-cell engraftment. Although our data was limited by only 28% (n=22) having lymphocyte subsets at M1, pediatric patients had lower T-cell counts (median 45.0 cells/µL, IQR: 6.50-118) compared to adults (median 723 cells/µL, IQR 618-1325) (Figure). Older recipient age and positive recipient CMV status were the only variables significantly associated with both CD4+ plus CD8+ count >100 cells/µL and donor CD3+ chimerism >90% (Table). Pediatric T-cell engraftment matched adult values at later time points except in patients with secondary GF and improvement in T-cell counts above 500 cells/µL at M2 was associated with a higher TNC dose (median 4.57x108 cells/µL, IQR 2.86-5.75 vs 1.74x108 cells/µL, IQR 1.55-2.24). We next evaluated the impact of low donor T-cell engraftment at M1. Patients with low donor T-cell engraftment had significantly higher rates of immune-mediated complications including secondary GF (CD3+ chimerism <90%: 42.9% vs 0%, p=0.001) and chronic GVHD (CD4+ plus CD8+ <100 cells/µL: 63.6% vs 9.1%, p=0.024). Incidence of viral reactivation was not different between cohorts. Disease and GVHD-free survival positively trended with donor T-cell engraftment (Table), and patients with both CD4+ plus CD8+ count <100 cells/µL and donor CD3+ chimerism <90% at M1 had severe immune-mediated complications, implicating an association of inadequate immune control with poor early donor T-cell engraftment. Conclusions: This analysis illustrates the importance of early T-cell engraftment in developing bi-directional immune tolerance following haploBMT. Although our study identified recipient age and CMV status as important factors in T-cell engraftment, the mechanism behind these factors, such as age-associated differences in drug metabolism and the role of CMV in promoting donor T-cell expansion, and how donor T cells promote tolerance require additional investigation. Our study demonstrates the importance of monitoring T-cell counts and sorted chimerism early post haploBMT and raises the question of how best to intervene in patients with low donor T-cell engraftment at M1. Our consortium plans to prospectively evaluate immune tolerance, including regulatory T-cell dynamics and impact of immune interventions at M1, to answer these important questions. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Use of the Cancer and Aging Research Group Predictive Model for Chemotherapy-Related Toxic Effects in a Multiethnic, Older Adult Asian Population

The Cancer and Aging Research Group (CARG) prediction model for chemotherapy-related toxic effects has been developed but not yet validated in older Asian adults. In view of differences in drug metabolism and toxic effect reporting in the Asian population, the ability of this tool to guide the cancer treatment decision-making process in older Asian adults needs to be assessed. To examine the validity of the CARG predictive model in a multiethnic Asian cohort of older adults. In this prognostic study, patients of various Asian ethnicities 70 years or older with a solid tumor diagnosis receiving chemotherapy at the National University Cancer Institute, Singapore, were accrued from June 1, 2017, to January 1, 2019. Their risks of chemotherapy-related toxic effects were calculated using the CARG tool. A geriatric assessment was performed, and the treating oncologist (blinded to the CARG scores) was asked to give an estimated likelihood of toxic effects (low, medium, or high). Chemotherapy-related toxic effects were recorded during each clinic visit. Validation of the prediction model was performed by calculating the area under the receiver operating characteristic curve. Multivariate analyses were performed to identify variables in other domains in the geriatric assessment predicting for severe toxic effects. Grade 3 to 5 toxic effects and hospitalization. The study included 200 patients (median age, 74 years [range, 70-89 years]; 110 [55.0%] male; 177 [88.5%] Chinese, 17 [8.5%] Malay, 4 [2.0%] Indian, and 2 [1.0%] other ethnicities [according to Singapore's national system of race classification]). A total of 137 patients (68.5%) experienced grade 3 to 5 toxic effects, and 131 (65.5%) required hospitalization. The area under the receiver operating characteristic curve for the CARG chemotoxicity prediction model was 0.74 (95% CI, 0.67-0.82), retaining good discrimination in the study population. This prognostic study conducted in a multiethnic Asian cohort of older adults supports the validity of the CARG predictive model in this population, predicting which older adults are at risk of chemotherapy-related toxic effects.

Gut Microbiome: The Interplay of an "Invisible Organ" with Herbal Medicine and Its Derived Compounds in Chronic Metabolic Disorders.

Resembling a concealed “organ” in a holobiont, trillions of gut microbes play complex roles in the maintenance of homeostasis, including participating in drug metabolism. The conventional opinion is that most of any drug is metabolized by the host and that individual differences are principally due to host genetic factors. However, current evidence indicates that only about 60% of the individual differences in drug metabolism are attributable to host genetics. Although most common chemical drugs regulate the gut microbiota, the gut microbiota is also known to be involved in drug metabolism, like the host. Interestingly, many traditional herbal medicines and derived compounds are biotransformed by gut microbiota, manipulating the compounds’ effects. Accordingly, the gut microbiota and its specified metabolic pathways can be deemed a promising target for promoting drug efficacy and safety. However, the evidence regarding causality and the corresponding mechanisms concerning gut microbiota and drug metabolism remains insufficient, especially regarding drugs used to treat metabolic disorders. Therefore, the present review aims to comprehensively summarize the bidirectional roles of gut microbiota in the effects of herbal medicine in metabolic diseases to provide vital clues for guiding the clinical application of precision medicine and personalized drug development.

In Vitro Models for Studying Chronic Drug-Induced Liver Injury.

Drug-induced liver injury (DILI) is a major clinical problem in terms of patient morbidity and mortality, cost to healthcare systems and failure of the development of new drugs. The need for consistent safety strategies capable of identifying a potential toxicity risk early in the drug discovery pipeline is key. Human DILI is poorly predicted in animals, probably due to the well-known interspecies differences in drug metabolism, pharmacokinetics, and toxicity targets. For this reason, distinct cellular models from primary human hepatocytes or hepatoma cell lines cultured as 2D monolayers to emerging 3D culture systems or the use of multi-cellular systems have been proposed for hepatotoxicity studies. In order to mimic long-term hepatotoxicity in vitro, cell models, which maintain hepatic phenotype for a suitably long period, should be used. On the other hand, repeated-dose administration is a more relevant scenario for therapeutics, providing information not only about toxicity, but also about cumulative effects and/or delayed responses. In this review, we evaluate the existing cell models for DILI prediction focusing on chronic hepatotoxicity, highlighting how better characterization and mechanistic studies could lead to advance DILI prediction.

Improving the predictive power of xenograft and syngeneic anti-tumour studies using mice humanised for pathways of drug metabolism.

Drug development is an expensive and time-consuming process, with only a small fraction of drugs gaining regulatory approval from the often many thousands of candidates identified during target validation. Once a lead compound has been identified and optimised, they are subject to intensive pre-clinical research to determine their pharmacodynamic, pharmacokinetic and toxicological properties, procedures which inevitably involve significant numbers of animals - mainly mice and rats, but also dogs and monkeys in much smaller numbers and for specific types of drug candidates. Many compounds that emerge from this process, having been shown to be safe and efficacious in pre-clinical studies, subsequently fail to replicate this outcome in clinical trials, therefore wasting time, money and, most importantly, animals. The poor predictive power of animal models in pre-clinical studies is predominantly due to lack of efficacy or safety reasons, which in turn can be attributed mainly to the significant species differences in drug metabolism between humans and animals. To circumvent this, we have developed a complex transgenic mouse model - 8HUM - which faithfully replicates human Phase I drug metabolism (and its regulation), and which will generate more human-relevant data [ REFINEMENT] from fewer animals [ REDUCTION] in a pre-clinical setting and reduce attrition in the clinic. One key area for the pre-clinical application of animals in an oncology setting - almost exclusively mice - is their use in anti-tumour studies. We now further demonstrate the utility of the 8HUM mouse using a murine melanoma cell line as a syngeneic tumour and also present an immunodeficient version 8HUM_Rag2 -/- - for use in xenograft studies. These models will be of significant benefit not only to Pharma for pre-clinical drug development work, but also throughout the drug efficacy, toxicology, pharmacology, and drug metabolism communities, where fewer animals will be needed to generate more human-relevant data.

Short- and long-term outcome of allogeneic stem cell transplantation in infants: A single-center experience over 20 years.

IntroductionAllogeneic hematopoietic stem cell transplantation (allo-HSCT) is a treatment method for a wide range of malignant and non-malignant diseases. Infants constitute a distinct patient group, especially due to their organ immaturity and differences in drug metabolism. The present paper aims to analyse the short- and long-term outcomes after allo-HSCT in infants.Material and methodsIn the study period, 67 patients under 12 months of age underwent allo-HSCT. This study is a retrospective analysis of patient medical records, in the form of paper and electronic documentation.ResultsThe probability of 5-year OS was 69% and 72% in patients with malignant and non-malignant diseases, respectively. The allo-HSCT from a matched donor was associated with improved OS in comparison to haploidentical donor (0.8 vs. 0.58%, p = 0.0425). The overall incidence of acute graft-vs.-host disease (aGVHD) was 59.3%, and grade III–IV aGVHD was diagnosed in 23% of patients. The 100-day non-relapse mortality (NRM) in the study cohort was 17.9%, while the 5-year NRM was 26.9%. Among the causes of NRM, infections occurred in 83.3% of patients, and aGVHD in 16.3% of individuals. Twenty-two children (32.8%) required hospitalization in the pediatric intensive care unit (PICU). The median length of PICU hospitalization was 6 days (range 1 to 12 days). Late sequelae diagnosed during post-transplant surveillance included ocular disorders in 26.8% of patients, cardiac complications in 4.4%, as well as endocrinopathy with short stature (<3rd percentile) in 37.2% and overt hypothyroidism in 35.4%. In the long-term perspective, 83.3% of survivors were able to attend a regular school.ConclusionsImprovements in unrelated donor availability, and better supportive care resulted in better outcomes. Management of infant allo-HSCT recipients requires the formation of multi-disciplinary specialist teams. In addition, the role of parental empowerment must be acknowledged; for example, in speech therapy and rehabilitation.

Sex Differences in Clopidogrel Effects Among Young Patients With Acute Coronary Syndrome: A Role for Genetics?

BackgroundPoorer health outcomes experienced by young women with acute coronary syndrome may be related to sex differences in the safety and efficacy of antiplatelet agents, such as clopidogrel. Polymorphisms in drug metabolism enzyme (cytochrome P450 [CYP] family) genes are independent factors for the variability in response to clopidogrel. However, a sex-specific impact of genetics to explain worse clinical outcomes in women has not been explored extensively. Therefore, our objective was to determine whether an interaction of sex with CYP variants occurs among users of clopidogrel, and if so, its impact on 1-year adverse clinical outcomes. MethodsWe used data from a combined cohort of 2272 patients (median age 49 years; 56% female) hospitalized for acute coronary syndrome. We examined interactions between sex and CYP variants among clopidogrel users at admission and discharge to assess associations with 1-year readmission due to cardiac events. ResultsThe case-only analysis of 177 participants on clopidogrel at the time of presentation showed that the risk of an atherothrombotic event was greater in female carriers of the CYP2C9∗3 loss-of-function allele (odds ratio = 3.77, 95% confidence interval = 1.54-9.24). The results of the multivariable logistic regression model for users of clopidogrel at discharge (n = 1733) indicated that women had significantly higher risk of atherothrombotic readmissions at 1 year (odds ratio = 1.55, 95% confidence interval = 1.16-2.07), compared to the risk for men, but the loss-of-function alleles, either individually or through a genetic risk score, were not associated with 1-year readmissions. ConclusionThis study highlights the need for an improved understanding of the role of sex-by-gene interactions in causing sex differences in drug metabolism.

Addressing Race, Ethnicity, and Structural Inequality in Pharmacology Education and Assessment

OBJECTIVESocial determinants of health, including race, ethnicity, and gender, represent important factors in health care delivery and patient outcomes, and contribute to health disparities. Pharmacology, as an integrated discipline, lies at the nexus between foundational science and clinical practice, providing a platform for educators to discuss the impact of social determinants on patient outcomes. Our goal is to create a framework that provides guidance for topics in pharmacotherapeutics for educators, learners, and providers to use in promoting antiracism in medical curricula.METHODSThrough iterative discussions, we developed a conceptual framework that includes topics taught across medical schools, such as drug metabolism, pharmacogenomics, adverse drug reactions, prescribing guidelines, factors affecting medication adherence, pain management, and therapeutic outcomes. Under each topic, we describe how social constructs such as race, ethnicity, and gender can impact pharmacology and therapeutic outcomes.RESULTSLiterature reports show that some topics in pharmacology education have already established cultural competency and should be adopted widely by all pharmacology educators, e.g., using more appropriate terminology for drug reactions such as vancomycin‐infusion reaction. Other topics are less established, so a more nuanced discussion with students is required. Society guidelines for managing diseases such as hypertension include prescribing recommendations based on race, with which learners are expected to be familiar as they enter clinical training but are actively being debated. Similarly, inter‐ethnic differences in drug metabolism are often reported as a function of genetic polymorphisms without considering non‐genetic factors.CONCLUSIONSWe have developed a conceptual framework for promoting antiracism in pharmacology education by categorizing topics based on those where cultural competencies are clearly established and those where a more nuanced discussion is required with learners, as well as identifying and reducing bias in assessment. These are generalizable across health professions in which pharmacology education is a discipline in the curriculum.

The Blind Spot of Pharmacology: A Scoping Review of Drug Metabolism in Prematurely Born Children.

The limit for possible survival after extremely preterm birth has steadily improved and consequently, more premature neonates with increasingly lower gestational age at birth now require care. This specialized care often include intensive pharmacological treatment, yet there is currently insufficient knowledge of gestational age dependent differences in drug metabolism. This potentially puts the preterm neonates at risk of receiving sub-optimal drug doses with a subsequent increased risk of adverse or insufficient drug effects, and often pediatricians are forced to prescribe medication as off-label or even off-science. In this review, we present some of the particularities of drug disposition and metabolism in preterm neonates. We highlight the challenges in pharmacometrics studies on hepatic drug metabolism in preterm and particularly extremely (less than 28 weeks of gestation) preterm neonates by conducting a scoping review of published literature. We find that >40% of included studies failed to report a clear distinction between term and preterm children in the presentation of results making direct interpretation for preterm neonates difficult. We present summarized findings of pharmacokinetic studies done on the major CYP sub-systems, but formal meta analyses were not possible due the overall heterogeneous approaches to measuring the phase I and II pathways metabolism in preterm neonates, often with use of opportunistic sampling. We find this to be a testament to the practical and ethical challenges in measuring pharmacokinetic activity in preterm neonates. The future calls for optimized designs in pharmacometrics studies, including PK/PD modeling-methods and other sample reducing techniques. Future studies should also preferably be a collaboration between neonatologists and clinical pharmacologists.

SAFETY MATTERS: THE TROUBLED AND FINALLY SUCCESSFUL STORY OF DIHYDROPYRIMIDINE DEHYDROGENASE PHARMACOGENETIC TEST IN CANCER PATIENTS

Pharmacogenetics investigates the molecular basis of inter-individual differences in drug metabolism and response. Sequence variations in genes encoding for metabolic enzymes may influence drug’s pharmacokinetics and/or pharmacodynamics, resulting in reduced efficacy and/or adverse drug reactions. The dihydropyrimidine dehydrogenase (DPD) deficiency is a clear example of how gene variants may affect fluoropyrimidines metabolism, and its … Continued