Dietary effects on drug metabolism and transport

Bioavailability of dronedarone tablets administered with or without food in healthy participants

Study objective

There is inadequate awareness of the effect of food on the bioavailability of dronedarone. We report results from two phase 1 studies assessing the effect of food on dronedarone's bioavailability.

Design setting and participants

Study 1; single-center, open-label, randomized study in healthy adults (males and females). Study 2; single-center, open-label, randomized study in healthy males.

Interventions

Study 1; a single 400-mg oral dose of dronedarone (marketed formulation) in fed (high-fat [47.4 g] meal) and fasted states. Study 2; a single 800-mg oral dose of dronedarone (two 400-mg tablets) after fat-rich (37.3 g) and low-fat (5.3 g) meals, and after fasting.

Main outcome measures

Pharmacokinetic parameters including maximum plasma concentration (Cmax) and area under the curve from time 0 to last measurable time (AUClast) were assessed for dronedarone and its active N-debutyl metabolite.

Results

Twenty-six participants were included in Study 1 and nine in Study 2. In Study 1, administration of 400 mg dronedarone with a high-fat meal vs. fasted state resulted in 2.8-fold and 2.0-fold increases in Cmax and AUClast, respectively. In Study 2, administration of 800 mg dronedarone with a fat-rich or low-fat meal vs. fasted state resulted in 4.6-fold and 3.2-fold increases in Cmax, respectively, and 3.1-fold and 2.3-fold increases, respectively, in AUClast. Results for the N-debutyl metabolite were similar to dronedarone. No adverse events were considered related to dronedarone.

Conclusion

With food, the bioavailability of dronedarone is markedly increased. In clinical practice, dronedarone should be administered with a complete meal to maximize drug absorption.

Nutrient competition predicts gut microbiome restructuring under drug perturbations

Human gut commensal bacteria are routinely exposed to various stresses, including therapeutic drugs, and collateral effects are difficult to predict. To systematically interrogate community-level effects of drug perturbations, we screened stool-derived in vitro communities with 707 clinically relevant small molecules. Across ∼5,000 community-drug interaction conditions, compositional and metabolomic responses were predictably impacted by nutrient competition, with certain species exhibiting improved growth due to adverse impacts on competitors. Changes to community composition were generally reversed by reseeding with the original community, although occasionally species promotion was long-lasting, due to higher-order interactions, even when the competitor was reseeded. Despite strong selection pressures, emergence of resistance within communities was infrequent. Finally, while qualitative species responses to drug perturbations were conserved across community contexts, nutrient competition quantitatively affected their abundances, consistent with predictions of consumer-resource models. Our study reveals that quantitative understanding of the interaction landscape, particularly nutrient competition, can be used to anticipate and potentially mitigate side effects of drug treatment on the gut microbiota.

Effect of eugenol on cytochrome P450 1A2, 2C9, 2D6, and 3A4 activity in human liver microsomes

This study aimed to provide an understanding of the influence of eugenol on CYP1A2, 2C9, 2D6, and 3A4 in human liver microsomes (HLM). Specific substrate for CYP1A2, 2C9, 2D6, and 3A4 were incubated in HLM with or without eugenol. The formation of their respective metabolites was assessed with HPLC analytical methods. Eugenol at 1, 10 and 100 µM levels inhibited the activity of CYP1A2 and CYP2C9 by 23.38 %, 23.57 %, 39.80 % and 62.82 %, 63.27 %, 67.70 % respectively. While, CYP2D6 and CYP3A4 activity was decreased by 40.70 %, 45.88 %, 62.68 % and 37.41 %, 42.58 % and 67.86 % at 1, 10 and 100 µM eugenol level respectively. The IC50 value of eugenol for CYP2D6 and CYP3A4 was calculated as 11.09 ± 3.49 µM and 13.48 ± 3.86 µM respectively. Potential herb-drug interactions was noted when eugenol is administered simultaneously with medications metabolized by these enzymes, most notably CYP2C9, CYP2D6 and CYP3A4.

Measurement of CYP1A2 and CYP3A4 activity by a simplified Geneva cocktail approach in a cohort of free-living individuals: a pilot study

Introduction: The cytochrome P450 enzyme subfamilies, including CYP3A4 and CYP1A2, have a major role in metabolism of a range of drugs including several anti-cancer treatments. Many factors including environmental exposures, diet, diseaserelated systemic inflammation and certain genetic polymorphisms can impact the activity level of these enzymes. As a result, the net activity of each enzyme subfamily can vary widely between individuals and in the same individual over time. This variability has potential major implications for treatment efficacy and risk of drug toxicity, but currently no assays are available for routine use to guide clinical decision-making. Methods: To address this, a mass spectrometry-based method to measure activities of CYP3A4, CYP1A2 was adapted and tested in free-living participants. The assay results were compared with the predicted activity of each enzyme, based on a self-report tool capturing diet, medication, chronic disease state, and tobacco usage. In addition, a feasibility test was performed using a low-volume dried blood spots (DBS) on two different filter-paper supports, to determine if the same assay could be deployed without the need for repeated standard blood tests. Results: The results confirmed the methodology is safe and feasible to perform in free-living participants using midazolam and caffeine as test substrates for CYP3A4 and CYP1A2 respectively. Furthermore, though similar methods were previously shown to be compatible with the DBS format, the assay can also be performed successfully while incorporating glucuronidase treatment into the DBS approach. The measured CYP3A4 activity score varied 2.6-fold across participants and correlated with predicted activity score obtained with the self-report tool. The measured CYP1A2 activity varied 3.5-fold between participants but no correlation with predicted activity from the self-report tool was found. Discussion: The results confirm the wide variation in CYP activity between individuals and the important role of diet and other exposures in determining CYP3A4 activity. This methodology shows great potential and future cross-sectional and longitudinal studies using DBS are warranted to determine how best to use the assay results to guide drug treatments.

Flavonoids as promising anticancer agents: an in silico investigation of ADMET, binding affinity by molecular docking and molecular dynamics simulations

Cancer is one of the most concerning diseases to humankind. Various treatment strategies are being employed for its treatment, out of which use of natural products is an essential one. Flavonoids have proven to be promising anticancer targets since decades. Also, tubulin is a significant biological target for the development of anticancer agents due to its crucial role in mitosis and abundance throughout the body. In the current study, in silico ADMET parameters of 104 flavonoids were examined, followed by molecular docking with the colchicine binding site of Tubulin protein (PDB; Id 4O2B). The best conformation from each flavonoid subcategory with the best docking score (MolDock score) was further subjected to 100 ns of molecular dynamics to investigate the protein-ligand complex's stability. Different parameters such as RMSD, RMSF, rGy and SASA were calculated for the six flavonoids using molecular dynamic studies. The top most compound from all the six subcategories of flavonoids elicited best behavior in the colchicine binding site of Tubulin protein. This in silico study employing molecular docking and molecular dynamics simulation provides strong evidence for flavonoids to be excellent anti-tubulin agents for the treatment of cancer.Communicated by Ramaswamy H. Sarma.

Caloric state modulates locomotion, heart rate and motor neuron responses to acute administration of d-amphetamine in zebrafish larvae

Psychostimulant drugs increase behavioral, cardiac and brain responses in humans and other animals. Acute food deprivation or chronic food restriction potentiates the stimulatory effects of abused drugs and increases the propensity for relapse to drug seeking in drug-experienced animals. The mechanisms by which hunger affects cardiac and behavioral activities are only beginning to be elucidated. Moreover, changes in motor neuron activities at the single neuron level induced by psychostimulants, and their modulation by food restriction, remain unknown. Here we investigated how food deprivation affects responses to d-amphetamine by measuring locomotor activity, cardiac output, and individual motor neuron activity in zebrafish larvae. We used wild-type larval zebrafish to record behavioral and cardiac responses and the larvae of Tg(mnx1:GCaMP5) transgenic zebrafish to record motor neuron responses. Physiological state gated responses to d-amphetamine. That is, d-amphetamine evoked significant increases in motor behavior (swimming distances), heart rate and motor neuron firing frequency in food-deprived but not fed zebrafish larvae. The results extend the finding that signals arising from food deprivation are a key potentiator of the drug responses induced by d-amphetamine to the zebrafish model. The larval zebrafish is an ideal model to further elucidate this interaction and identify key neuronal substrates that may increase vulnerability to drug reinforcement, drug-seeking and relapse.

Comparative pharmacokinetics of seven bioactive components after oral administration of crude and processed Qixue Shuangbu Prescription in chronic heart failure rats by microdialysis combined with UPLC-MS/MS

ETHNOPHARMACOLOGICAL RELEVANCE

Qixue Shuangbu Prescription (QSP) is a classical traditional Chinese medicine prescription, which has widely used for the treatment of chronic heart failure (CHF). Preliminary clinical studies have shown that the efficacy of processed QSP (P-QSP) in treating CHF is greater than crude QSP (C-QSP). However, the pharmacokinetic characteristics of its major bioactive components under pathological conditions are unclear.

AIM OF STUDY

This study aims to compare pharmacokinetics of seven bioactive components after oral administration of C-QSP and P-QSP in CHF model rats.

MATERIALS AND METHODS

Ginsenoside Rb1, ginsenoside Re, ginsenoside Rg1, ferulic acid, astragaloside IV, calycosin-7-O-β-D-glucoside, and paeoniflorin in QSP were used as the target components. CHF model in rats was induced by the intraperitoneal injection of doxorubicin. A microdialysis combined with UPLC-MS/MS method was first established to compare the pharmacokinetics of seven major bioactive components in CHF model rats after oral administration of C-QSP and P-QSP.

RESULTS

This method was successfully applied to the pharmacokinetic investigation of seven major components of C-QSP and P-QSP following oral administration in CHF model rats. Compared with the C-QSP group, the C_max, AUC_0-t and AUC_0-∞ of ginsenoside Rb1, ginsenoside Re, ginsenoside Rg1, ferulic acid, astragaloside IV and paeoniflorin significantly increased (P < 0.05) in the P-QSP group, which suggested that the absorptivity and bioavailability were increased. Lower T_1/2, MRT_0-t of ginsenoside Rb1, gerulic acid and higher T_1/2, MRT_0-t of ginsenoside Rb1, astragaloside IV, paeoniflorin in the P-QSP group, which indicated that eliminated more quickly or slowly, respectively.

CONCLUSIONS

The pharmacokinetic parameters of bioactive components were significantly changed for better bioavailability and absorption, longer lasting time elimination, which were beneficial for enhancing therapeutic efficacy in the P-QSP group. This study will provide a new perspective to explain the pharmacokinetic-pharmacodynamic correlation of P-QSP on the treatment of CHF.

A burst of fenoterol excretion during the recovery of a weight loss protocol

Fenoterol is a sympathomimetic β2 receptor agonist primarily used as a bronchodilator. Due to its sympathomimetic actions, the World Anti-Doping Agency (WADA) has banned it. Multiple acute weight loss protocols (WLP) are used by Olympic athletes for sports that segregate athletes by weight; these generally involve caloric and water deprivation combined with heat exposure. Athletes use WLP before weigh-in, then transition to different body acute weight regain protocols (WRP) before competitions. Here, we studied the pharmacokinetics of fenoterol under WLP conditions: energetic dietary restriction, decreased water intake, and exposure to a dry sauna (80 ± 2 °C), followed by a WRP. Five elite-level female judo athletes participated in the study. Four received fenoterol (200 μg; n = 2 or 400 μg; n = 2), while one was a control receiving placebo under identical conditions. We measured excretion of the fenoterol parent molecule and presented qualitative data of its sulfated metabolite using QqQ tandem quadrupole mass spectrometry for 118 h. The fenoterol parent appeared earlier in urine than did its conjugated metabolite; excretion profiles were similar among all subjects. The centers of mass for fenoterol parent curves were (time, fenoterol): athlete A (10.9, 7.3); athlete B (9.2, 27.3); athlete C (8.5, 6.9); athlete D (9.7, 5.0). After initiating WRP, we observed a burst in urinary fenoterol excretion once in complete decay. This trend was observed for all four athletes who received fenoterol. Our results suggest that during hypohydration, some of the unmetabolized fenoterol accumulates in tissues, then is released during rehydration. These findings can be important for detecting fenoterol use in athletes.

Nutrition and Calcitonin Gene Related Peptide (CGRP) in Migraine

Targeting calcitonin gene-related peptide (CGRP) and its receptor by antibodies and antagonists was a breakthrough in migraine prevention and treatment. However, not all migraine patients respond to CGRP-based therapy and a fraction of those who respond complain of aliments mainly in the gastrointestinal tract. In addition, CGRP and migraine are associated with obesity and metabolic diseases, including diabetes. Therefore, CGRP may play an important role in the functioning of the gut-brain-microflora axis. CGRP secretion may be modulated by dietary compounds associated with the disruption of calcium signaling and upregulation of mitogen-activated kinase phosphatases 1 and 3. CGRP may display anorexigenic properties through induction of anorexigenic neuropeptides, such as cholecystokinin and/or inhibit orexigenic neuropeptides, such as neuropeptide Y and melanin-concentrating hormone CH, resulting in the suppression of food intake, functionally coupled to the activation of the hypothalamic 3',5'-cyclic adenosine monophosphate. The anorexigenic action of CGRP observed in animal studies may reflect its general potential to control appetite/satiety or general food intake. Therefore, dietary nutrients may modulate CGRP, and CGRP may modulate their intake. Therefore, anti-CGRP therapy should consider this mutual dependence to increase the efficacy of the therapy and reduce its unwanted side effects. This narrative review presents information on molecular aspects of the interaction between dietary nutrients and CGRP and their reported and prospective use to improve anti-CGRP therapy in migraine.

Design and Optimization of 1H-1,2,3-Triazole-4-carboxamides as Novel, Potent, and Selective Inverse Agonists and Antagonists of PXR

The pregnane X receptor (PXR) is a key regulator of drug metabolism. Many drugs bind to and activate PXR, causing adverse drug responses. This suggests that PXR inhibitors have therapeutic value, but potent PXR inhibitors have so far been lacking. Herein, we report the structural optimization of a series of 1H-1,2,3-triazole-4-carboxamides compounds that led to the discovery of compound 85 as a selective and the most potent inverse agonist and antagonist of PXR, with low nanomolar IC50 values for binding and cellular activity. Importantly, compound 89, a close analog of 85, is a selective and pure antagonist with low nanomolar IC50 values for binding and cellular activity. This study has provided novel, selective, and most potent PXR inhibitors (a dual inverse agonist/antagonist and a pure antagonist) for use in basic research and future clinical studies and also shed light on how to reduce the binding affinity of a compound to PXR.

Short-Term High-Fat Diet Alters Acetaminophen Metabolism in Healthy Individuals

BACKGROUND

Acetaminophen is metabolized through a nontoxic sulfation and glucuronidation pathway and toxic oxidation pathway (via CYP2E1 and CYP1A2). A short-term high-fat diet induces alterations in the steatotic liver and may alter hepatic drug enzyme activity. In the case of acetaminophen, these alterations may result in an increased risk of hepatotoxicity. Therefore, this study was conducted to assess the effect of a 3-day hypercaloric high-fat diet on the plasma levels of acetaminophen metabolites.

METHODS

Nine healthy subjects participated in this randomized, crossover intervention study. The subjects consumed a regular diet or a regular diet supplemented with 500 mL of cream (1700 kcal) for 3 days and then fasted overnight. After ingesting 1000-mg acetaminophen, the plasma concentration of acetaminophen (APAP) and its metabolites [acetaminophen glucuronide, acetaminophen sulfate, 3-cysteinyl-acetaminophen, and 3-(N-acetyl-L-cystein-S-yl)-acetaminophen, and 3-methoxy-acetaminophen] were measured.

RESULTS

The 3-day high-fat diet increased the extrapolated area under the concentration-time curve from 0 to infinity (area under the curve 0-inf ) of APAP-Cys by approximately 20% ( P = 0.02) and that from 0 to 8 hours (area under the curve 0-8 ) of APAP-Cys-NAC by approximately 39% ( P = 0.01). The 3-day high-fat diet did not alter the pharmacokinetic parameters of the parent compound acetaminophen and other metabolites.

CONCLUSIONS

A short-term, hypercaloric, high-fat diet increases the plasma levels of the APAP metabolites formed by the oxidation pathway, which may increase the risk of hepatotoxicity.

Individual Efficacy and Community Impact of Ivermectin, Diethylcarbamazine, and Albendazole Mass Drug Administration for Lymphatic Filariasis Control in Fiji: A Cluster Randomized Trial

BACKGROUND

Bancroftian filariasis remains endemic in Fiji despite >10 years of mass drug administration (MDA) using diethylcarbamazine and albendazole (DA). The addition of ivermectin to this combination (IDA) has improved efficacy of microfilarial clearance at 12 months in individually randomized trials in nocturnal transmission settings, but impact in a setting of diurnally subperiodic filarial transmission has not been evaluated.

METHODS

This cluster randomized study compared the individual efficacy and community impact of IDA vs DA as MDA for lymphatic filariasis in 35 villages on 2 islands of Fiji. Participants were tested at enrollment for circulating filarial antigen and, if positive, for microfilariae. Weight-dosed treatment was offered according to village randomization. Communities were visited at 12 months and retested for lymphatic filariasis. Infected individuals from Rotuma were retested at 24 months.

RESULTS

A total of 3816 participants were enrolled and 3616 were treated. At 12 months, microfilariae clearance was achieved in 72 of 111 participants detected with infection at baseline, with no difference in efficacy between treatment groups: DA, 69.2% (95% confidence interval [CI], 57.2%-79.1%) vs IDA, 62.5% (95% CI, 43.6%-78.2%); risk difference, 11.3 % (95% CI, -10% to 32.7%); P = .30. There was no difference between treatment groups in community prevalence of microfilariae at 12 months or individual clearance at 24 months.

CONCLUSIONS

We found no difference between IDA and DA in individual clearance or community prevalence of lymphatic filariasis at 12 months, and no improved efficacy following a second annual round of IDA. Possible explanations for the apparent lack of benefit of IDA compared to DA include drug and parasite factors affecting clearance, and higher than expected reinfection rates. Clinical Trials Registration: NCT03177993 and Australian New Zealand Clinical Trial Registry: N12617000738325.

Fed or fasted state for oral therapies in breast cancer treatment? A comprehensive review of clinical practice recommendations

In the last decades several anti-cancer drugs have been developed to treat patients with breast cancer, many of them orally administered, with ongoing efforts to substitute parenteral drugs with oral therapy. The latter is attractive because of its convenience and ease of administration, finally improving quality of life. The drawback of oral administration is that exposure to the drug is affected by different factors and the high variability, combined with the relatively narrow therapeutic index of most of these agents, would predispose some individuals to risk for treatment inefficacy or increase toxicity. Among these factors, food plays a central role since it can influence the pharmacokinetic profile of several drugs. Consequently, health care providers and patients should be aware of possible interaction to optimize treatment. In this review a systematic evaluation of package inserts and literature have been performed to analyse the effect of fed or fasted state on pharmacokinetic of all oral drugs currently approved for breast cancer, offering clear recommendations for their use daily practice.

Nanoparticulate Drug Delivery Strategies to Address Intestinal Cytochrome P450 CYP3A4 Metabolism towards Personalized Medicine

Drug dosing in clinical practice, which determines optimal efficacy, toxicity or ineffectiveness, is critical to patients' outcomes. However, many orally administered therapeutic drugs are susceptible to biotransformation by a group of important oxidative enzymes, known as cytochrome P450s (CYPs). In particular, CYP3A4 is a low specificity isoenzyme of the CYPs family, which contributes to the metabolism of approximately 50% of all marketed drugs. Induction or inhibition of CYP3A4 activity results in the varied oral bioavailability and unwanted drug-drug, drug-food, and drug-herb interactions. This review explores the need for addressing intestinal CYP3A4 metabolism and investigates the opportunities to incorporate lipid-based oral drug delivery to enable precise dosing. A variety of lipid- and lipid-polymer hybrid-nanoparticles are highlighted to improve drug bioavailability. These drug carriers are designed to target different intestinal regions, including (1) local saturation or inhibition of CYP3A4 activity at duodenum and proximal jejunum; (2) CYP3A4 bypass via lymphatic absorption; (3) pH-responsive drug release or vitamin-B12 targeted cellular uptake in the distal intestine. Exploitation of lipidic nanosystems not only revives drugs removed from clinical practice due to serious drug-drug interactions, but also provide alternative approaches to reduce pharmacokinetic variability.

It's not all about inhaled treatment: challenges with oral therapy in paediatric respiratory medicine

Advances in therapies and management of conditions encountered by paediatric respiratory specialists have led to improved outcomes and improved survival rates dramatically in chronic diseases such as cystic fibrosis. However, this has also meant an increase in treatment burden. A variety of inhaled treatments are crucial in managing paediatric respiratory diseases, but these patients also have to take many oral medications. It is widely recognised that developing oral formulations appropriate for the paediatric population can affect how well a product is received by patients and their families. Consideration should be given to palatability and the number of medicines to be administered as these can all contribute to treatment adherence.

Polypharmacy specifically in the context of management of patients with cystic fibrosis is not a new concept, but the recently introduced cystic fibrosis transmembrane conductance regulator (CFTR) modulator therapies and their potential for interactions and adverse reactions create novel challenges. There are some strategies that families and healthcare professionals can implement to reduce treatment burden. This review will also provide some insight into the life of a teenager with cystic fibrosis and the relative complexities of her treatment and the impacts on daily life.

In children, medications given by the oral route can be challenging to administer, add to the burden of care and contribute to poor adherence. Additionally, polypharmacy increases the chances of interactions between oral medications.https://bit.ly/3fxgXQU

A Bioequivalence Study of Avanafil in Healthy Chinese Male Subjects Under Fasting and Fed Conditions: Results of a Randomized, Open-Label, Single-Dose, 2-Sequence, 2-Period Crossover Study

This bioequivalence study was conducted to determine the pharmacokinetics and safety profiles of an originator and a generic avanafil formulation in Chinese male subjects under fed and fasting conditions. Each eligible subject was initially randomly given avanafil (200 mg) in a test‐reference or reference‐test order, before being switched to another study drug sequence after 7 drug‐free days. The bioequivalence of test and reference avanafil were determined if the 90%CIs of the geometric mean ratio (GMR) for the area under plasma concentration‐time curve (AUC) from time 0 to infinity (AUC_0‐∞), AUC from time 0 to the last detectable concentration (AUC_0‐t), and the maximum plasma concentration (C_max) fell within the range 80%‐125%. Under fasting/fed conditions, the 90%CIs of GMR for AUC_0‐∞, AUC_0‐t, and C_max were 98.9% to 109.5%/96.0% to 101.2%, 99.6% to 110.3%/96.6% to 102.4%, and 99.3% to 116.8%/94.3% to 106.7%, respectively, which were all within the 80%‐125% range. Adverse events (AEs) occurred in 20.8% of subjects under fasting conditions and 20.7% of subjects under fed conditions, with a severity of grade 1. No significant difference was found in the rate of occurrence of AEs and drug‐related AEs in the test and reference‐avanafil groups (all P > .05). We concluded that the test and reference avanafil were bioequivalent in healthy Chinese male subjects under fasting and fed conditions.

Meta-Analysis of Food Effect on Oral Absorption of Efflux Transporter Substrate Drugs: Does Delayed Gastric Emptying Influence Drug Transport Kinetics?

The oral route of drug administration is the most convenient method of drug delivery, but it is associated with variable bioavailability. Food is one of the major factors that affect oral drug absorption by influencing drug properties (e.g., solubility and dissolution rate) and physiological factors (e.g., metabolism and transport across the gastrointestinal tract). The aim of this work was to investigate the effect of food on the high-affinity intestinal efflux transporter substrate drugs. We hypothesized that transport efficiency is higher in the fed state as compared to the fasted state because of the lower intestinal lumen drug concentration due to prolonged gastric emptying time. A systematic analysis of reported clinical food-effect (FE) studies on 311 drugs was performed and the association of the efflux transport efficiency was investigated on the FE magnitude, i.e., changes in maximal plasma concentration and area under the plasma concentration-time profile curve for both solubility and permeability-limited drugs. In total, 124 and 88 drugs showed positive and negative FE, respectively, whereas 99 showed no FE. As expected, the solubility-limited drugs showed positive FE, but interestingly, drugs with a high potential for efflux transport, were associated with negative FE. Moreover, a high-fat diet was associated with a higher magnitude of negative FE for high-affinity efflux transporter substrates as compared to a low-fat diet. To account for changes in drug absorption after food intake, the prolonged gastric emptying time should be considered in the physiologically based pharmacokinetic (PBPK) modeling of orally absorbed efflux transporter substrate drugs.

Physiologically Based Pharmacokinetic/Pharmacodynamic Modeling to Support Waivers of In Vivo Clinical Studies: Current Status, Challenges, and Opportunities

Physiologically based pharmacokinetic/pharmacodynamic (PBPK/PD) modeling has been extensively applied to quantitatively translate in vitro data, predict the in vivo performance, and ultimately support waivers of in vivo clinical studies. In the area of biopharmaceutics and within the context of model-informed drug discovery and development (MID3), there is a rapidly growing interest in applying verified and validated mechanistic PBPK models to waive in vivo clinical studies. However, the regulatory acceptance of PBPK analyses for biopharmaceutics and oral drug absorption applications, which is also referred to variously as "PBPK absorption modeling" [Zhang et al. CPT: Pharmacometrics Syst. Pharmacol. 2017, 6, 492], "physiologically based absorption modeling", or "physiologically based biopharmaceutics modeling" (PBBM), remains rather low [Kesisoglou et al. J. Pharm. Sci. 2016, 105, 2723] [Heimbach et al. AAPS J. 2019, 21, 29]. Despite considerable progress in the understanding of gastrointestinal (GI) physiology, in vitro biopharmaceutic and in silico tools, PBPK models for oral absorption often suffer from an incomplete understanding of the physiology, overparameterization, and insufficient model validation and/or platform verification, all of which can represent limitations to their translatability and predictive performance. The complex interactions of drug substances and (bioenabling) formulations with the highly dynamic and heterogeneous environment of the GI tract in different age, ethnic, and genetic groups as well as disease states have not been yet fully elucidated, and they deserve further research. Along with advancements in the understanding of GI physiology and refinement of current or development of fully mechanistic in silico tools, we strongly believe that harmonization, interdisciplinary interaction, and enhancement of the translational link between in vitro, in silico, and in vivo will determine the future of PBBM. This Perspective provides an overview of the current status of PBBM, reflects on challenges and knowledge gaps, and discusses future opportunities around PBPK/PD models for oral absorption of small and large molecules to waive in vivo clinical studies.

Bioequivalence of two esomeprazole magnesium enteric-coated formulations in healthy Chinese subjects

BACKGROUND

The pharmacokinetics and bioequivalence of esomeprazole in healthy Chinese subjects and the effects of food on the pharmacokinetics have not been well studied.

AIM

To evaluate the pharmacokinetic characteristics of esomeprazole magnesium (Eso) enteric- coated capsule in the healthy subjects in China and the bioequivalence of the two formulations.

METHODS

This study was conducted in the Phase I Clinical Trial Unit of the Affiliated Hospital of Changchun University of Chinese Medicine. A total of 64 healthy subjects were enrolled in the study. Thirty-two subjects fasted or fed, took the test or reference formulation Eso enteric-coated capsule by a four-cycle, two-sequence crossover of fasting/fed, self-controlled method. The liquid chromatography-mass spectrometry was performed to determine the drug plasma concentration at 16 different time points within 12 h after drug administration. The pharmacokinetic parameters C_max, area under the curve (AUC)_0-t, and AUC_0-inf were calculated to evaluate the bioequivalence.

RESULTS

Pharmacokinetic parameters were evaluated after subjects took the test formulation and control formulation under fasting status. The ratio of geometric means of C_max was 104.15%, with a confidence interval (CI) of 98.20-110.46%. The ratio of geometric means of AUC_0-t was 105.26%, with a CI of 99.80-111.01%. The ratio of geometric means of AUC_0-inf was 105.37%, with a CI of 99.97-111.06%. The pharmacokinetic parameters were also evaluated after subjects took the reference formulation of Eso enteric-coated capsule after eating. The upper limit of 95% CI of the geometric mean ratio of pharmacokinetic parameters of Eso enteric-coated capsules in the postprandial state C_max was -0.1689, and the point estimate was 0.9509 (0.80-1.25). The upper limit of 95% CI of the geometric mean ratio of pharmacokinetic parameters of Eso enteric-coated capsules in the postprandial state AUC_0-t was -0.1015 (≤ 0) , and the point estimate was 0.9003 (0.80-1.25). The upper limit of 95% CI of the geometric mean ratio of pharmacokinetic parameters of Eso enteric-coated capsules in the postprandial state AUC_0-inf was -0.0593 (≤ 0), and the point estimate was 0.8453 (0.80-1.25). The results indicated that the two formulations were bioequivalent under both fasting and fed states.

CONCLUSION

The two types of esomeprazole tablets were bioequivalent under both fasting and fed states, and both were generally well tolerated.

Clinical implications of food-drug interactions with small-molecule kinase inhibitors

During the past two decades, small-molecule kinase inhibitors have proven to be valuable in the treatment of solid and haematological tumours. However, because of their oral administration, the intrapatient and interpatient exposure to small-molecule kinase inhibitors (SMKIs) is highly variable and is affected by many factors, such as concomitant use of food and herbs. Food-drug interactions are capable of altering the systemic bioavailability and pharmacokinetics of these drugs. The most important mechanisms underlying food-drug interactions are gastrointestinal drug absorption and hepatic metabolism through cytochrome P450 isoenzymes. As food-drug interactions can lead to therapy failure or severe toxicity, knowledge of these interactions is essential. This Review provides a comprehensive overview of published studies involving food-drug interactions and herb-drug interactions for all registered SMKIs up to Oct 1, 2019. We critically discuss US Food and Drug Administration (FDA) and European Medicines Agency (EMA) guidelines concerning food-drug interactions and offer clear recommendations for their management in clinical practice.

Effect of Food and an Animal's Sex on P-Glycoprotein Expression and Luminal Fluids in the Gastrointestinal Tract of Wistar Rats

The rat is one of the most commonly used animal models in pre-clinical studies. Limited information between the sexes and the effect of food consumption on the gastrointestinal (GI) physiology, however, is acknowledged or understood. This study aimed to investigate the potential sex differences and effect of food intake on the intestinal luminal fluid and the efflux membrane transporter P-glycoprotein (P-gp) along the intestinal tract of male and female Wistar rats. To characterise the intestinal luminal fluids, pH, surface tension, buffer capacity and osmolality were measured. Absolute P-gp expression along the intestinal tract was quantified via liquid chromatography-tandem mass spectrometry (LC-MS/MS). In general, the characteristics of the luminal fluids were similar in male and female rats along the GI tract. In fasted male rats, the absolute P-gp expression gradually increased from the duodenum to ileum but decreased in the colon. A significant sex difference (p < 0.05) was identified in the jejunum where P-gp expression in males was 83% higher than in females. Similarly, ileal P-gp expression in male rats was approximately 58% higher than that of their female counterparts. Conversely, following food intake, a significant sex difference (p < 0.05) in P-gp expression was found but in a contrasting trend. Fed female rats expressed much higher P-gp levels than male rats with an increase of 77% and 34% in the jejunum and ileum, respectively. A deeper understanding of the effects of sex and food intake on the absorption of P-gp substrates can lead to an improved translation from pre-clinical animal studies into human pharmacokinetic studies.

Scientific Regulatory Policy Committee Points to Consider*: Nuisance Factors, Block Effects, and Batch Effects in Nonclinical Safety Assessment Studies

Detection of test article-related effects and the determination of the adversity of those changes are the primary goals of nonclinical safety assessment studies for drugs and chemicals in development. During these studies, variables that are not of primary interest to investigators may change and influence data interpretation. These variables, often referred to as "nuisance factors," may influence other groups of data and result in "block or batch effects" that complicate data interpretation. Definitions of the terms "nuisance factors," "block effects," and "batch effects," as they apply to nonclinical safety assessment studies, are reviewed. Multiple case examples of block and batch effects in safety assessment studies are provided, and the challenges these bring to pathology data interpretation are discussed. Methods to mitigate the occurrence of block and batch effects in safety assessment studies, including statistical blocking and utilization of study designs that minimize potential confounding variables, incorporation of adequate randomization, and use of an appropriate number of animals or repeated measurement of specific parameters for increased precision, are reviewed. [Box: see text].

Effect of resveratrol on dipeptidyl peptidase-4 inhibitors pharmacokinetics: An in vitro and in vivo approach

Diabetes mellitus (DM) is a metabolic disorder with hyperglycemia being its hallmark symptom. The secondary symptom of DM is oxidative stress, which leads to the generation of free radicals. Diabetic nephropathy and neuropathy is the long-term effect of oxidative stress caused in DM, which leads to damage of kidneys and neurons respectively. Resveratrol (RES) is a phytochemical, found to be effective in the treatment of diabetic nephropathy and neuropathy. Due to its antioxidant property, it reduces the oxidative stress caused by DM. Dipeptidyl peptidase-4 (DPP-4) inhibitors are used for the treatment of type 2 DM. In vitro and in vivo data depicted that the metabolism of alogliptin (ALO), saxagliptin (SAX) and sitagliptin (SIT) were decreased in presence of RES while metabolism of teneligliptin (TEN) was not affected in presence of RES. The results show that the alteration of the pharmacokinetics of ALO, SAX and SIT was due to inhibition of CYP P450 by RES. Thus, there was a significant pharmacokinetic interaction between RES-ALO, RES-SAX and RES-SIT. Hence, a dose reduction is required when RES therapy is taken in combination with ALO, SAX and SIT as there is an increase in drug exposure, which might lead to toxicity.

Intestinal Absorption of Isoalantolactone and Alantolactone, Two Sesquiterpene Lactones from Radix Inulae, Using Caco-2 Cells

BACKGROUND

Isoalantolactone and alantolactone are the main sesquiterpene lactones in Radix Inulae (dried root of Inula helenium L. or I. racemosa Hook. F.), which is a frequently utilized herbal medicine. They also occur in several plants and have various pharmacologic effects. However, they have been found to have poor oral bioavailability in rats.

OBJECTIVES

To understand the intestinal absorptive characteristics of isoalantolactone and alantolactone as well specific influx and efflux transporters in their absorption.

METHODS

Bidirectional permeabilities of isoalantolactone and alantolactone were investigated across Caco-2 cell monolayers. Transport assays were performed using different concentrations of two lactones and specific inhibitors of ATP-binding cassette transporters and influx transporters.

RESULTS

The absorption permeability of isoalantolactone and alantolactone was high at the tested concentrations (5, 20 and 80 μmol/l), and the major permeation mechanism of both lactones was found to be passive diffusion with active efflux mediated by multidrug resistance-associated proteins (MRPs) and breast cancer resistance protein (BCRP).

CONCLUSION

Our results demonstrated that the absorption permeability of isoalantolactone and alantolactone was good in the Caco-2 cell model. The isoalantolactone and alantolactone absorption elucidated in this study provides useful information for further pharmacokinetics studies. Since low intestinal absorption can now be ruled out as a cause, further studies are needed to explain the low oral bioavailability of the two sesquiterpene lactones.

Pharmacomicrobiomics: The Holy Grail to Variability in Drug Response?

The human body, with 3.0 × 10¹³ cells and more than 3.8 × 10¹³ microorganisms, has nearly a one-to-one ratio of resident microbes to human cells. Initiatives like the Human Microbiome Project, American Gut, and Flemish Gut have identified associations between microbial taxa and human health. The study of interactions between microbiome and pharmaceutical agents, i.e., pharmacomicrobiomics, has revealed an instrumental role of the microbiome in modulating drug response that alters the therapeutic outcomes. In this review, we present our current comprehension of the relationship of the microbiome, host biology, and pharmaceutical agents such as cardiovascular drugs, analgesics, and chemotherapeutic agents to human disease and treatment outcomes. We also discuss the significance of studying diet-gene-drug interactions and further address the key challenges associated with pharmacomicrobiomics. Finally, we examine proposed models employing systems biology for the application of pharmacomicrobiomics and other -omics data, and provide approaches to elucidate microbiome-drug interactions to improve future translation to personalized medicine.

The mechanisms of pharmacokinetic food-drug interactions - A perspective from the UNGAP group

The simultaneous intake of food and drugs can have a strong impact on drug release, absorption, distribution, metabolism and/or elimination and consequently, on the efficacy and safety of pharmacotherapy. As such, food-drug interactions are one of the main challenges in oral drug administration. Whereas pharmacokinetic (PK) food-drug interactions can have a variety of causes, pharmacodynamic (PD) food-drug interactions occur due to specific pharmacological interactions between a drug and particular drinks or food. In recent years, extensive efforts were made to elucidate the mechanisms that drive pharmacokinetic food-drug interactions. Their occurrence depends mainly on the properties of the drug substance, the formulation and a multitude of physiological factors. Every intake of food or drink changes the physiological conditions in the human gastrointestinal tract. Therefore, a precise understanding of how different foods and drinks affect the processes of drug absorption, distribution, metabolism and/or elimination as well as formulation performance is important in order to be able to predict and avoid such interactions. Furthermore, it must be considered that beverages such as milk, grapefruit juice and alcohol can also lead to specific food-drug interactions. In this regard, the growing use of food supplements and functional food requires urgent attention in oral pharmacotherapy. Recently, a new consortium in Understanding Gastrointestinal Absorption-related Processes (UNGAP) was established through COST, a funding organisation of the European Union supporting translational research across Europe. In this review of the UNGAP Working group "Food-Drug Interface", the different mechanisms that can lead to pharmacokinetic food-drug interactions are discussed and summarised from different expert perspectives.

Changes in the Expression of Aquaporin-3 in the Gastrointestinal Tract Affect Drug Absorption

Aquaporin-3 (AQP3) plays an important role in water transport in the gastrointestinal (GI) tract. In this study, we conducted a Caco-2 cell permeability assay to examine how changes in the expression and function of AQP3 affect the rate at which a drug is absorbed via passive transport in the GI tract. When the function of AQP3 was inhibited by mercuric chloride or phloretin, there was no change in warfarin permeability. In contrast, when the expression of AQP3 protein was decreased by prostaglandin E₂ (PGE₂) treatment, warfarin permeability increased to approximately twice the control level, and membrane fluidity increased by 15%. In addition, warfarin permeability increased to an extent comparable to that after PGE₂ treatment when cell membrane fluidity was increased by 10% via boric acid/EDTA treatment. These findings suggest the possibility that the increased drug absorption under decreased AQP3 expression was attributable to increased membrane fluidity. The results of this study demonstrate that the rate of water transport has little effect on drug absorption. However, our findings also indicate that although AQP3 and other similar transmembrane proteins do not themselves transport drugs, changes in their expression levels can cause changes in cell membrane fluidity, thus affecting drug absorption rates.

RNA interference screen identifies NAA10 as a regulator of PXR transcription

The pregnane X receptor (PXR) is a principal xenobiotic receptor crucial in the detection, detoxification, and clearance of toxic substances from the body. PXR plays a vital role in the metabolism and disposition of drugs, and elevated PXR levels contribute to cancer drug resistance. Therefore, to modulate PXR activity and mitigate drug resistance, it is imperative to fully understand its regulation. To this end, we screened a transcription factor siRNA library in pancreatic cancer cells that express high levels of PXR. Through a comprehensive deconvolution process, we identified N-alpha-acetyltransferase 10 (NAA10) as a factor in the transcriptional machinery regulating PXR transcription. Because no one single factor has 100% operational control of PXR transcriptional regulation, our results together with other previous findings suggest that the transcriptional regulation of PXR is complex and that multiple factors contribute to the process including NAA10.

Food for thought: formulating away the food effect - a PEARRL review

OBJECTIVES

Co-ingestion of oral dosage forms with meals can cause substantial changes in bioavailability relative to the fasted state. Food-mediated effects on bioavailability can have significant consequences in drug development, regulatory and clinical settings. To date, the primary focus of research has focused on the ability to mechanistically understand the causes and predict the occurrence of these effects.

KEY FINDINGS

The current review describes the mechanisms underpinning the occurrence of food effects, sheds new insights on the relative frequency for newly licensed medicines and describes the various methods by which they can be overcome. Analysis of oral medicines licensed by either the EMA or FDA since 2010 revealed that over 40% display significant food effects. Due to altered bioavailability, these medicines are often required to be dosed, rather restrictively, in either the fed or the fasted state, which can hinder clinical usefulness.

SUMMARY

There are clinical and commercial advantages to predicting the presence of food effects early in the drug development process, in order to mitigate this risk of variable food effect bioavailability. Formulation approaches aimed at reducing variable food-dependent bioavailability, through the use of bio-enabling formulations, are an essential tool in addressing this challenge and the latest state of the art in this field are summarised here.

Effects of food restriction on the expression of genes related to acetaminophen-induced liver toxicity in rats

It is well known that fasting substantially affects the metabolism of drugs and chemicals. Food restriction also affects drug kinetics, such as absorption, metabolism, and excretion, and therefore, it can potentially modulate the onset of chemical toxicity or drug-induced adverse reactions. In the present study, the expression of drug-metabolizing enzyme genes and total glutathione content in the liver, which are related to toxicity induced by overdose of the hepatotoxic drug acetaminophen (N-acetyl-p-aminophenol; APAP), were examined in rats reared under different feeding conditions: ad libitum feeding, 16-h fasting, and food restriction (fed 70% of the average intake of ad libitum feeding for 10 days) conditions. The rats under food restriction conditions as well as fasted rats showed significantly higher expression of Cyp2e1, the gene encoding the enzyme that metabolizes APAP to its toxic metabolite N-acetyl-p-benzoquinone imine (NAPQI). They also had lower levels of liver total glutathione, which detoxifies NAPQI. In contrast, the gene expression of UDP-glucuronosyltransferase 1A6 (Ugt1a6), sulfotransferase 1A1 (Sult1a1), and glutathione S-transferase M1 (Gstm1) was not affected by food restriction or fasting. When APAP was administered (800 mg/kg), histopathological changes were not observed in rats fed ad libitum, while hepatocellular necrosis was observed in most of the rats treated with APAP after fasting or food restriction. Taken together, these results suggest that not only fasting but also food restriction exacerbate APAP-induced acute liver injury, probably by the induction of CYP2E1 and the reduction of liver glutathione contents, in rodents.

Pharmacomicrobiomics: a novel route towards personalized medicine?

Inter-individual heterogeneity in drug response is a serious problem that affects the patient's wellbeing and poses enormous clinical and financial burdens on a societal level. Pharmacogenomics has been at the forefront of research into the impact of individual genetic background on drug response variability or drug toxicity, and recently the gut microbiome, which has also been called the second genome, has been recognized as an important player in this respect. Moreover, the microbiome is a very attractive target for improving drug efficacy and safety due to the opportunities to manipulate its composition. Pharmacomicrobiomics is an emerging field that investigates the interplay of microbiome variation and drugs response and disposition (absorption, distribution, metabolism and excretion). In this review, we provide a historical overview and examine current state-of-the-art knowledge on the complex interactions between gut microbiome, host and drugs. We argue that combining pharmacogenomics and pharmacomicrobiomics will provide an important foundation for making major advances in personalized medicine.

The role of hepatic cytochrome P450s in the cytotoxicity of dronedarone

Dronedarone is used to treat patients with cardiac arrhythmias and has been reported to be associated with liver injury. Our previous mechanistic work demonstrated that DNA damage-induced apoptosis contributes to the cytotoxicity of dronedarone. In this study, we examined further the underlying mechanisms and found that after a 24-h treatment of HepG2 cells, dronedarone caused cytotoxicity, G1-phase cell cycle arrest, suppression of topoisomerase II, and DNA damage in a concentration-dependent manner. We also investigated the role of cytochrome P450s (CYPs)-mediated metabolism in the dronedarone-induced toxicity using our previously established HepG2 cell lines expressing individually 14 human CYPs (1A1, 1A2, 1B1, 2A6, 2B6, 2C8, 2C9, 2C18, 2C19, 2D6, 2E1, 3A4, 3A5, and 3A7). We demonstrated that CYP3A4, 3A5, and 2D6 were the major enzymes that metabolize dronedarone, and that CYP3A7, 2E1, 2C19, 2C18, 1A1, and 2B6 also metabolize dronedarone, but to a lesser extent. Our data showed that the cytotoxicity of dronedarone was decreased in CYP3A4-, 3A5-, or 2D6-overexpressing cells compared to the control HepG2 cells, indicating that the parent dronedarone has higher potency than the metabolites to induce cytotoxicity in these cells. In contrast, cytotoxicity was increased in CYP1A1-overexpressing cells, demonstrating that CYP1A1 exerts an opposite effect in dronedarone's toxicity, comparing to CYP3A4, 3A5, or 2D6. We also studied the involvement of topoisomerase II in dronedarone-induced toxicity, and demonstrated that the overexpression of topoisomerase II caused an increase in cell viability and a decrease in γ-H2A.X induction, suggesting that suppression of topoisomerase II may be one of the mechanisms involved in dronedarone-induced liver toxicity.

Effects of processing adjuvants on traditional Chinese herbs

Processing of Chinese medicines is a pharmaceutical technique that transforms medicinal raw materials into decoction pieces for use in different therapies. Various adjuvants, such as vinegar, wine, honey, and brine, are used in the processing to enhance the efficacy and reduce the toxicity of crude drugs. Proper processing is essential to ensure the quality and safety of traditional Chinese medicines (TCMs). Therefore, sound knowledge of processing principles is crucial to the standardized use of these processing adjuvants and to facilitate the production and clinical use of decoction pieces. Many scientific reports have indicated the synergistic effects of processing mechanisms on the chemistry, pharmacology, and pharmacokinetics of the active ingredients in TCMs. Under certain conditions, adjuvants change the content of active or toxic components in drugs by chemical or physical transformation, increase or decrease drug dissolution, exert their own pharmacological effects, or alter drug pharmacokinetics. This review summarizes various processing methods adopted in the last two decades, and highlights current approaches to identify the effects of processing parameters on TCMs.

Modulation of CYP3A enzyme activity by diosmin and its consequence on carbamazepine pharmacokinetics in rats

Diosmin is a widely used flavonoid for the treatment of varicose veins and hemorrhoids. Epileptic patients with hemorrhoids and varicose veins may use diosmin along with carbamazepine (CBZ) therapy, which leads to pharmacokinetic interaction between diosmin and CBZ. Therefore, the present study was performed to evaluate the effect of diosmin on the pharmacokinetics of CBZ in rats. Diosmin-mediated altered CYP3A enzyme activity in human and rat liver microsomes was examined using CYP3A dependent erythromycin N-demethylase assay. Further, an in vivo pharmacokinetic study of oral administered CBZ in rats with and without diosmin pretreatment was performed. The CYP3A enzyme activity in human and rat liver microsomes was significantly (p < 0.05) decreased by diosmin when compared to control. Pretreatment with diosmin significantly (p < 0.05) enhanced maximum plasma concentration (C _max), area under the curve (AUC), and half life (t _1/2), while significantly (p < 0.05) decreased elimination rate constant (k _el) and apparent oral clearance (CL/F) of CBZ as compared to control rats. On the other hand, C _max, AUC, and t _1/2 of carbamazepine 10, 11-epoxide (CBZE) were significantly (p < 0.05) decreased after diosmin pretreatment. Furthermore, diosmin pretreatment significantly (p < 0.05) decreased metabolic ratios of C _max and AUC when compared to control, suggesting reduced formation of CBZ to CBZE. The results suggest that diosmin pretreatment might have inhibited CYP3A-mediated metabolism of CBZ. Accordingly, caution should be taken when diosmin is used in combination with therapeutic drugs metabolized by CYP3A enzyme in addition to CBZ.

PXR: More Than Just a Master Xenobiotic Receptor

Pregnane X receptor (PXR) is a nuclear receptor considered to be a master xenobiotic receptor that coordinately regulates the expression of genes encoding drug-metabolizing enzymes and drug transporters to essentially detoxify and eliminate xenobiotics and endotoxins from the body. In the past several years, the function of PXR in the regulation of xenobiotic metabolism has been extensively studied, and the role of PXR as a xenobiotic sensor has been well established. It is now clear, however, that PXR plays many other roles in addition to its xenobiotic-sensing function. For instance, recent studies have discovered previously unidentified roles of PXR in inflammatory response, cell proliferation, and cell migration. PXR also contributes to the dysregulation of these processes in diseases states. These recent discoveries of the role of PXR in the physiologic and pathophysiologic conditions of other cellular processes provides the possibility of novel targets for drug discovery. This review highlights areas of PXR regulation that require further clarification and summarizes the recent progress in our understanding of the nonxenobiotic functions of PXR that can be explored for relevant therapeutic applications.

Interpreting quantitative urine buprenorphine and norbuprenorphine levels in office-based clinical practice

BACKGROUND

Quantitative urine buprenorphine testing is used to monitor patients receiving buprenorphine for the treatment of opioid use disorder (OUD), however the interpretation of urine buprenorphine testing is complex. Currently, interpretation of quantitative buprenorphine testing is guided by data from drug assay development studies and forensic labs rather than clinical treatment cohorts.

METHODS

In this retrospective study, we describe the patterns of urine buprenorphine and norbuprenorphine levels in patients prescribed sublingual buprenorphine for OUD in an office-based addiction treatment clinic. Urine buprenorphine and norbuprenorphine levels were analyzed in patients who reported having adulterated their urine, patients clinically suspected of adulterating their urine, and patients without concern for urine adulteration. Finally, we tested the accuracy of urine buprenorphine, norbuprenorphine, and norbuprenorphine: buprenorphine ratio (Norbup:Bup) to identify adulterated urine samples.

RESULTS

Patients without suspicion for urine adulteration rarely provided specimens with buprenorphine >=1000ng/ml (4.4%), while the proportion provided by those who endorsed or were suspected of urine adulteration was higher (42.9%, 40.6%, respectively). Compared to patients without reported urine adulteration, specimens from patients who reported or were suspected of urine adulteration had significantly higher buprenorphine (p=0.0001) and lower norbuprenorphine (<0.0001) levels, and significantly lower Norbup:Bup ratios (p=0.04). Buprenorphine >=700ng/ml offered the best accuracy for discriminating between adulterated and non-adulterated specimens.

CONCLUSION

This study describes the patterns of urine buprenorphine and norbuprenorphine levels from patients with OUD receiving buprenorphine treatment in an office-based addiction treatment clinic. Parameters for identifying urine adulterated by submerging buprenorphine medication in the urine specimen are discussed.

Adulteration and Counterfeiting of Online Nutraceutical Formulations in the United States: Time for Intervention?

Global prevalence of nutraceuticals is noticeably high. The American market is flooded with nutraceuticals claiming to be of natural origin and sold with a therapeutic claim by major online retail stores such as Amazon and eBay. The objective of this commentary is to highlight the possible problems of online-sold nutraceuticals in the United States with respect to claim, adulterants, and safety. Furthermore, there is a lack of strict regulatory laws governing the sales, manufacturing, marketing, and label claims of nutraceutical formulations currently sold in the U.S. market. Major online retail stores and Internet pharmacies aid the widespread sale of nutraceuticals. Finally, according to the literature, many of these products were found to be either counterfeit or adulterated with active pharmaceutical ingredients (API) and mislabeled as being safe and natural. Therefore, regulatory authorities along with the research community should intervene to draw attention to these products and their possible effects.

In Silico Prediction for Intestinal Absorption and Brain Penetration of Chemical Pesticides in Humans

Intestinal absorption and brain permeation constitute key parameters of toxicokinetics for pesticides, conditioning their toxicity, including neurotoxicity. However, they remain poorly characterized in humans. The present study was therefore designed to evaluate human intestine and brain permeation for a large set of pesticides (n = 338) belonging to various chemical classes, using an in silico graphical BOILED-Egg/SwissADME online method based on lipophilicity and polarity that was initially developed for drugs. A high percentage of the pesticides (81.4%) was predicted to exhibit high intestinal absorption, with a high accuracy (96%), whereas a lower, but substantial, percentage (38.5%) displayed brain permeation. Among the pesticide classes, organochlorines (n = 30) constitute the class with the lowest percentage of intestine-permeant members (40%), whereas that of the organophosphorus compounds (n = 99) has the lowest percentage of brain-permeant chemicals (9%). The predictions of the permeations for the pesticides were additionally shown to be significantly associated with various molecular descriptors well-known to discriminate between permeant and non-permeant drugs. Overall, our in silico data suggest that human exposure to pesticides through the oral way is likely to result in an intake of these dietary contaminants for most of them and brain permeation for some of them, thus supporting the idea that they have toxic effects on human health, including neurotoxic effects.

Fexofenadine, a Putative In Vivo P-glycoprotein Probe, Fails to Predict Clearance of the Substrate Tacrolimus in Renal Recipients

Whether the combined use of probe drugs for CYP3A4 and P-glycoprotein can clarify the relative contribution of these proteins to pharmacokinetic variability of a dual substrate like tacrolimus has never been assessed. Seventy renal recipients underwent simultaneous 8-h pharmacokinetic profiles for tacrolimus, the CYP3A4 probe midazolam, and the putative P-glycoprotein probe fexofenadine. Patients were genotyped for polymorphisms in CYP3A5, CYP3A4, ABCB1, ABCC2 and SLCO2B1, -1B1, and 1B3. Carriers of the ABCB1 2677G>A polymorphism displayed lower fexofenadine C_max (-66%; P = 0.012) and a trend toward higher clearance (+157%; P = 0.078). Predictors of tacrolimus clearance were CYP3A5 genotype, midazolam clearance, hematocrit, weight, and age (R² = 0.61). Fexofenadine pharmacokinetic parameters were not predictive of tacrolimus clearance. In conclusion, fexofenadine pharmacokinetics varied considerably between renal recipients but most of this variability remained unexplained, with only minor effects of genetic polymorphisms. Fexofenadine cannot be used to assess in vivo CYP3A4-P-glycoprotein interplay in tacrolimus-treated renal recipients.

Glucose-dependent regulation of pregnane X receptor is modulated by AMP-activated protein kinase

Pregnane X receptor (PXR) is a xenobiotic receptor that regulates the detoxification and clearance of drugs and foreign compounds from the liver. There has been mounting evidence of crosstalk between the drug metabolism pathway and the energy metabolism pathway, but little is known about this cross-regulation. To further delineate the energy metabolism and drug metabolism crosstalk in this study, we exposed HepG2 cells to varying glucose concentrations. We observed that PXR activity was induced under high-glucose conditions. This finding is consistent with previous clinical reports of increased drug clearance in patients with untreated diabetes. We demonstrated that AMP-activated protein kinase (AMPK) modulates PXR transcriptional activity and that pharmacologically manipulated AMPK activation exhibits an inverse relation to PXR activity. Activation of AMPK was shown to downregulate PXR activity and, consistent with that, potentiate the response of cells to the drug. Taken together, our results delineate a hitherto unreported axis of regulation that involves the energy status of the cell, PXR regulation, and drug sensitivity.

Assessment of ethnic differences in sunitinib outcome between Caucasian and Asian patients with metastatic renal cell carcinoma: a meta-analysis

BACKGROUND

An increasing number of studies have reported ethnic differences in sunitinib outcome in metastatic renal cell carcinoma (mRCC) patients. However, a comprehensive analysis is still lacking. Therefore, we systematically collected available published data and performed a meta-analysis to compare sunitinib efficacy and toxicity in Asian and Caucasian mRCC patients.

METHODS

Data were extracted from published results from clinical trials, expanded access program and real-world clinical practice. Progression-free survival (or time to tumor progression), overall survival, objective response rate and adverse events were used as endpoints to evaluate the differences of sunitinib outcome between the two ethnicities. For adverse events, we focused the following clinically relevant side effects: diarrhea, fatigue, mucositis/stomatitis, hand-foot syndrome, hypertension, leukopenia, neutropenia and thrombocytopenia.

RESULTS

A total of 33 publications including 9977 patients were available for meta-analysis. The efficacy of sunitinib in Asian patients was similar to that in Caucasian patients. However, Asian patients showed a higher incidence of all grades toxicity of hand-foot syndrome, > grade 2 fatigue, > grade 2 hand-foot syndrome and > grade 2 thrombocytopenia.

CONCLUSION

Ethnic differences in adverse events of sunitinib in mRCC patients existed and dose adjustment in Asian patients may be considered.

Effect of Food on the Pharmacokinetics of the Investigational Aurora A Kinase Inhibitor Alisertib (MLN8237) in Patients with Advanced Solid Tumors

Objective

This study was conducted to characterize the effects of food on single-dose pharmacokinetics (PK) of the investigational Aurora A kinase inhibitor alisertib (MLN8237) in patients with advanced solid tumors.

Methods

Following overnight fasting for 10 h, a single 50 mg enteric-coated tablet (ECT) of alisertib was administered under either fasted (alisertib with 240 mL of water) or fed (high-fat meal consumed 30 min before receiving alisertib with 240 mL of water) conditions using a two-cycle, two-way crossover design. Patients on both arms were not allowed food for 4 h post-dose. Water was allowed as desired, except for 1 h before and after alisertib administration.

Results

Twenty-four patients were enrolled and 14 patients were PK-evaluable (ten patients were not PK-evaluable due to insufficient data). Following a single oral dose of alisertib, median t_max was 6 h and 3 h under fed and fasted conditions, respectively. The geometric mean ratio of AUC_inf (fed- vs. fasted-state dosing) was 0.94 [90 % confidence interval (CI) 0.68–1.32]. The geometric mean C_max under fed conditions was 84 % of that under fasted conditions (90 % CI 66–106). Alisertib was generally well-tolerated; most common drug-related grade 3/4 adverse events included neutropenia (50 %), leukopenia (38 %), and thrombocytopenia (21 %).

Conclusions

Systemic exposures achieved following a single 50 mg dose of alisertib administered as an ECT formulation after a high-fat meal are similar to those observed in the fasted state. Alisertib 50 mg ECT can be administered without regard for food.

ClinicalTrials.gov Identifier

NCT00962091.

Influence of diosmin on the metabolism and disposition of carbamazepine in healthy subjects

1. Carbamazepine (CBZ) is an antiepileptic drug with narrow therapeutic window and administration in humans receiving long-term therapy with diosmin (DSN) may occur, which leads to CYP3A4-mediated drug interactions. The purpose of the present study was to assess the influence of DSN on the metabolism and pharmacokinetics of CBZ in healthy volunteers. 2. An open-label, sequential, two-period study was conducted in 12 healthy male volunteers. A single dose of DSN 500 mg was administered once daily for 10 days during treatment phase. A single dose of CBZ 200 mg was administered during control and after treatment phases under fasting conditions. The blood samples were collected after CBZ dosing at predetermined time intervals and analyzed by LC-MS/MS. 3. Treatment with DSN significantly enhanced the maximum plasma concentration (C_max)_, area under the curve (AUC), half-life (t_1/2) and significantly decreased the apparent oral clearance (CL/F) and elimination rate constant (K_el) of CBZ. On the other hand, treatment with DSN significantly decreased the C_max and AUC of carbamazepine 10, 11-epoxide (CBZE). Furthermore, treatment with DSN significantly decreased the metabolite to parent ratios of C_max and AUC, indicating the reduced metabolism of CBZ to CBZE. 4. The results suggest that the altered CYP3A4 enzyme activity and pharmacokinetics of CBZ might be attributed to DSN-mediated inhibition of CYP3A4 enzyme, which indicates pharmacokinetic interaction present between DSN and CBZ. Therefore, we conclude that DSN has an inhibiting effect on the metabolism and disposition of CBZ.

Effect of nine diets on mRNAs of phase-II conjugation enzymes in livers of mice

1. Phase-II enzymes are important in metabolizing many xenobiotics including prescription drugs and chemical carcinogens. Whereas it is known that diet can alter the expression of phase-II conjugation enzymes, the previous studies are limited in using only two or three diets and examining only a few enzymes. 2. Adult male C57BL6 mice were fed one of nine diets for 3 weeks. Of the 87 genes encoding major hepatic phase-II enzymes, approximately one-half (43) were altered by at least one diet. Diet restriction altered the hepatic expression of the most genes encoding phase-II enzymes (27), followed by lab chow (15), atherogenic diet (13), high-fat diet (10), western diet (7), high-fructose diet (5), and essential fatty acid-deficient diet (3), whereas the low n-3 fatty acid diet had no effect on the hepatic expression of these phase-II enzymes. 3. This comprehensive study provides detailed information on which conjugation enzymes are changed by these diets, and these data can be used to further investigate the mechanism for these changes in messenger RNAs, and whether these changes result in alterations in enzyme activity and drug action.

High fat diet aggravates the nephrotoxicity of berberrubine by influencing on its pharmacokinetic profile

Berberrubine (BRB), the active metabolite of berberine (BBR), possesses various pharmacological activities. In this study, we found BRB showed not only a stronger lipid-lowering effect than berberine but also a specific nephrotoxicity in mice fed with high fat diet (HFD). To explore the underlying mechanism, the pharmacokinetics of BRB were evaluated. There was a greater in vivo exposure of BRB in C57BL/6J mice fed with HFD than with routine chows, in terms of Cmax, AUC0-t, levels of BRB in kidney and urinary excretion. Moreover, in vitro assessment clearly showed BRB had a toxic effect on renal cell lines, while the primary metabolite, berberrubine-9-O-β-d-glucuronide (BRBG), did not show any obvious toxicity. These results suggested HFD aggravated BRB-induced nephrotoxicity by promoting the in vivo exposure of BRB especially in urine and kidney. Although our previous study indicated BRB could be metabolized into BRBG, BRBG did not show any obvious toxicity in vitro.

A short-term high fat diet increases exposure to midazolam and omeprazole in healthy subjects

OBJECTIVES

Knowledge of factors contributing to variation in drug metabolism is of vital importance to optimize drug treatment. This study assesses the effects of a short-term hypercaloric high fat diet on metabolism of five oral drugs, which are each specific for a single P450 isoform: midazolam (CYP3A4), omeprazole (CYP2C19), metoprolol (CYP2D6), S-warfarin (CYP2C9) and caffeine (CYP1A2).

METHODS

In 9 healthy volunteers, pharmacokinetics of the five drugs were assessed after an overnight fast at two separate occasions: after a regular diet and after 3 days of a hypercaloric high fat diet (i.e. regular diet supplemented with 500 mL cream [1715 kcal, 35% fat]). Pharmacokinetic parameters (mean [SEM]) were estimated by non-compartmental analysis.

RESULTS

The high fat diet increased exposure to midazolam by 19% from 24.7 (2.6) to 29.5 (3.6) ng ml-1h-1 (p=0.04) and exposure to omeprazole by 31% from 726 (104) to 951 (168) ng ml-1h-1 (p=0.05). Exposure to metoprolol, caffeine and S-warfarin was not affected by the high fat diet.

CONCLUSION

A short-term hypercaloric high fat diet increases exposure to midazolam and omeprazole, possibly reflecting modulation of CYP3A4 and CYP2C19.

Use of an Acetyl Derivative to Improve GC-MS Determination of Norbuprenorphine in the Presence of High Concentrations of Buprenorphine in Urine

Certain patients being treated with Suboxone™ or Subutex™ can exhibit very high buprenorphine and low norbuprenorphine concentrations in urine. Very high buprenorphine can interfere with buprenorphine-D4 used as an internal standard, causing errors in norbuprenorphine determination by gas chromatography-mass spectrometry (GC-MS). We used a modified method of Wu et al. to introduce norbuprenorphine-D3 as a separate internal standard for norbuprenorphine. This allowed us to accurately measure norbuprenorphine in neat urine specimens when buprenorphine is present in extremely high concentrations. Laboratories measuring buprenorphine and metabolite by GC-MS may face this problem if their clientele includes patients being treated with other medications that interfere with the cytochrome p450 CYP 3A4-mediated conversion of buprenorphine to norbuprenorphine.