The Changing Landscape for Human Absorption, Metabolism, and Excretion: Practical Experiences From a Data Analysis of 500 Studies.

Coincidental with the intensified regulatory and industry focus on the design and conduct of human absorption, metabolism, and excretion (hAME) studies in the past 12 months, we have recently completed our 500th cohort involving radiolabeled test item administration to humans. Here, we build upon a recent industry white paper in this journal1 and share some of our own experiences as a Contract Research Organization based upon collaborations with numerous pharma companies and their differing approaches to design and timing, to add further context to the discussion regarding hAME studies and the pivotal role that drug metabolism and pharmacokinetics plays. In this article, we explore how both changing relationships within the industry and shifting regulatory guidelines are impacting strategies, and compare EU and US pre-study approval requirements, before evaluating the trends from over 500 studies conducted at our global facilities conducted over more than 30 years. We conclude with a review of how improved technical capabilities and strategies are influencing the design and conduct of hAME studies, before speculating on some of the driving factors which may shape the direction they take in the future.

Refining Procedures within Regulatory Toxicology Studies: Improving Animal Welfare and Data.

During the development of potential new medicines or agrochemicals, an assessment of the safety profile to humans and environmental species is conducted using a range of different in silico and in vitro techniques in conjunction with metabolism and toxicity studies using animals. The required studies are outlined within international regulatory guidelines which acknowledge and support the application of the 3Rs to reduce the number of animals used or to refine the procedures performed when these studies are deemed to be necessary. The continued development of new technologies and adoption of best-practice approaches to laboratory animal housing and study procedures has generated a series of refinements that can be incorporated into animal studies throughout the package. These refinements benefit the welfare of fish, mice, rats, rabbits, dogs, minipigs, and non-human primates (NHPs) whilst maintaining or improving data quality within general toxicology, metabolism, and other studies and can also bring efficiencies to processes that benefit study costs and timings. Examples are shared which cover the following topics: social housing of dogs and NHPs, surgical refinements in the rat bile duct cannulation model for collection of data for metabolism studies, whether fasting is really required prior to clinical pathology sampling, and the use of microsampling for toxicokinetics.

A new group housing approach for non-human primate metabolism studies.

Understanding the absorption, distribution, metabolism and excretion (ADME) of candidate drugs in preclinical species is an integral part of the safety and efficacy evaluation in drug development. For this purpose, the housing of single animals in metabolism cages has historically been common practice for ADME studies. Whilst mini-pigs and dogs are selected wherever possible, non-human primates (NHPs) are used where there is no suitable scientific alternative. Having undergone only minimal revisions over the past 30 years, the traditional single-housing metabolism cage design for NHPs significantly limits normal vertical movement and social behaviours in primates. Minimising animal suffering and improving welfare is an important aspect of working with animals in research and Novo Nordisk A/S, together with collaborators, has focused on this area for many years. A novel metabolism cage for group housing of NHPs has been designed in a joint collaboration between Novo Nordisk A/S and Covance Inc. The advantages of this novel cage are extensive, including a significantly increased cage volume and ability for socialisation, as well as improvements to alleviate stress and boredom. The excretion balance data from six male NHPs housed in single or group metabolism cages were compared using the radiolabelled test compound [14C]-quetiapine. Welfare, in terms of stress and behaviour, when animals were single or group housed was also assessed. Mean recoveries of radioactivity were shown to be comparable irrespective of housing design (83.2% for group-housed animals vs. 87.1% for single-housed animals), supporting the potential suitability of NHP group housing for future metabolism ADME studies.

A novel welfare and scientific approach to conducting dog metabolism studies allowing dogs to be pair housed.

Metabolism cages are designed to conduct absorption, distribution, metabolism and excretion (ADME) studies, enabling an 'excretion balance' scientific objective to be met. Historically, the design of dog metabolism cages has involved single housing. This type of housing has limitations for normal social behaviours and has been largely unchanged for 25-30 years. Improving animal welfare is a focus area for the authorities as well as the industry throughout the European Union. A collaboration was developed between Novo Nordisk and Covance to enhance the design of metabolism cages, allowing dogs to be pair housed. The purpose of the study was to compare excretion balance data from pair-housed and singly housed dogs in order to demonstrate that conducting excretion balance studies with a pair-housing design improves animal welfare without compromising the scientific integrity of the study. A radiolabelled test compound, [14C]-Quetiapine, was selected for this investigation based on its excretion profile. The assessment of the dogs' stress levels was investigated by measuring the levels of serum cortisol as an indicative biomarker. Results were inconclusive due to large variations in cortisol levels. However, dogs appeared calmer in the pair-housing setting. The overall mean recovery (±standard deviation) for pair-housed animals (94.0 ± 0.66% of the dose) was equivalent to that from singly housed dogs (93.0 ± 2.29%). Based on these data, we conclude that pair housing of dogs for future metabolism ADME studies does not compromise the scientific integrity, and therefore is a major progression in the design of these studies, enhancing welfare.

Pharmacokinetics of the SABRE agent 4,6-d2-nicotinamide and also nicotinamide in rats following oral and intravenous administration.

To prepare the way for using the isotopically labelled SABRE hyperpolarized 4,6-d2-nicotinamide as an MRI agent in humans we have performed an in-vivo study to measure its pharmacokinetics in the plasma of healthy rats after intravenous and oral administration. Male Han Wistar rats were dosed with either 4,6-d2-nicotinamide or the corresponding control, non-labelled nicotinamide, and plasma samples were obtained at eight time points for up to 24 h after administration. Pharmacokinetic parameters were determined from agent concentration-versus-time data for both 4,6-d2-nicotinamide and nicotinamide. 4,6-d2-Nicotinamide proved to be well tolerated regardless of route of administration at the concentrations used (20, 80 and 120 mg/kg). Pharmacokinetic parameters were similar after oral and intravenous administration and similar to those obtained for nicotinamide. Analysis of nicotinamide plasma concentrations after dosing 4,6-d2-nicotinamide intravenously demonstrates a reversible exchange of endogenous nicotinamide by this labelled agent over the time-course of our assays. Supported by a large body of evidence for the safety of nicotinamide when dosed orally in humans, we conclude that 4,6-d2-nicotinamide can also be safely administered intravenously, which will provide significant benefit when using this agent for planned imaging studies in humans.

Care home resident and staff perceptions of the acceptability of nutrition intervention trial procedures: a qualitative study embedded within a cluster randomised feasibility trial.

OBJECTIVES: To examine care home resident and staff perceptions of the acceptability of participating in a feasibility trial evaluating nutritional interventions in the treatment of malnutrition. DESIGN: Exploratory qualitative methodology was used to gather descriptions of resident and staff perceptions of trial procedures, using semi-structured interviews with residents and focus groups with staff. The interviews were used to explore individual perceptions of the acceptability of the assigned intervention and the outcomes measured. Focus groups were used to explore staff experiences of trial participation and perspectives of nutritional support interventions. SETTING: The study was embedded within a cluster randomised feasibility trial, which randomised six care homes to provide standard care (SC), food-based (FB) intervention or oral nutritional supplement (ONS) intervention to residents with, or at risk of, malnutrition. PARTICIPANTS: Residents in the trial with capacity to consent (n=7) formed the sampling frame for inclusion. Four agreed to be approached by the researcher and to take part in the individual interviews. All were women, representing two arms of the trial (ONS and SC). Twelve staff participated in six focus groups, one at each care home. All participants were women, representing all three arms of the trial. RESULTS: Major themes that emerged from both interviews and focus groups included the perceived acceptability of trial involvement, the value of residents completing participant-reported outcome measures and the challenges associated with outcomes measurement in this setting. Themes that emerged from the focus groups alone, included the importance of individualising an intervention, and the perceived value of FB and ONS interventions and dietetic input. CONCLUSIONS: Residents and staff perceived involvement in a trial evaluating nutritional interventions to be acceptable, although the challenges associated with research in this setting were acknowledged. Resident preferences were highlighted by staff as an important consideration when implementing a nutrition support plan. TRIAL REGISTRATION NUMBER: ISRCTN38047922.

The Effects of Probiotics and Symbiotics on Risk Factors for Hepatic Encephalopathy: A Systematic Review.

Alterations in the levels of intestinal microbiota, endotoxemia, and inflammation are novel areas of interest in the pathogenesis of hepatic encephalopathy (HE). Probiotics and symbiotics are a promising treatment option for HE due to possible beneficial effects in modulating gut microflora and might be better tolerated and more cost-effective than the traditional treatment with lactulose, rifaximin or L-ornithine-L-aspartate. A systematic search of the electronic databases PubMed, ISI Web of Science, EMBASE, and Cochrane Library was conducted for randomized controlled clinical trials in adult patients with cirrhosis, evaluating the effect of probiotics and symbiotics in changes on intestinal microflora, reduction of endotoxemia, inflammation, and ammonia, reversal of minimal hepatic encephalopathy (MHE), prevention of overt hepatic encephalopathy (OHE), and improvement of quality of life. Nineteen trials met the inclusion criteria. Probiotics and symbiotics increased beneficial microflora and decreased pathogenic bacteria and endotoxemia compared with placebo/no treatment, but no effect was observed on inflammation. Probiotics significantly reversed MHE [risk ratio, 1.53; 95% confidence interval (CI): 1.14, 2.05; P=0.005] and reduced OHE development (risk ratio, 0.62; 95% CI: 0.48, 0.80; P=0.0002) compared with placebo/no treatment. Symbiotics significantly decreased ammonia levels compared with placebo (15.24; 95% CI: -26.01, -4.47; P=0.006). Probiotics did not show any additional benefit on reversal of MHE and prevention of OHE development when compared with lactulose, rifaximin, and L-ornithine-L-aspartate. Only 5 trials considered tolerance with minimal side effects reported. Although further research is warranted, probiotics and symbiotics should be considered as an alternative therapy for the treatment and management of HE given the results reported in this systematic review.

A cluster randomised feasibility trial evaluating nutritional interventions in the treatment of malnutrition in care home adult residents.

BACKGROUND: Protein energy malnutrition (PEM) predisposes individuals to disease, delays recovery from illness and reduces quality of life. Care home residents in the United Kingdom are especially vulnerable, with an estimated 30 to 42 % at risk. Evidence for nutritional interventions to address PEM in the care home setting is lacking. Widely used techniques include food-based intervention and/or the use of prescribed oral nutritional supplements. To define outcomes and optimise the design for an adequately powered definitive trial to compare the efficacy of established nutritional interventions in this setting, a cluster randomised feasibility trial with a 6-month intervention was undertaken. METHODS: Care home residents with or at risk of malnutrition were identified across six UK care home sites from September to December 2013. Homes were cluster randomised to standard care (SC), food-based intervention (FB) or oral nutritional supplement intervention (ONS), for 6 months. Key outcomes were trial feasibility and the acceptability of design, allocated interventions and outcome assessments. Anthropometry, dietary intake, healthcare resource usage and participant-reported outcome measures were assessed at baseline and at 3 and 6 months. RESULTS: All six care homes approached were recruited and retained. Of the 110 residents at risk of malnutrition, 85 % entered the trial, and 68 % completed the 6-month intervention. Pre-specified success criteria for feasibility were met for recruitment and retention, intervention acceptability (resident compliance ≥60 %) and measurement of weight, body mass index (BMI), mid-upper arm circumference and dietary intake (data completeness >80 %). Measurement of handgrip strength and triceps skinfold thickness was not found to be feasible in this population. The 95 % confidence interval (CI) data suggested sensitivity to change in dietary intake for weight, BMI and energy intake between baseline and 3 months when each intervention (FB and ONS) was compared with SC. CONCLUSIONS: A definitive trial comparing the efficacy of nutritional support interventions in increasing weight and BMI in malnourished care home residents can be conducted. However, whilst the design was feasible, this trial has highlighted the lack of clinically and patient-relevant outcome measures that are appropriate for use in this setting for both research and clinical practice. In particular, this trial identified a need for a more simple measure of functional status, which considers the limitations of functional tests in the care home population. TRIAL REGISTRATION: Current Controlled Trials ISRCTN38047922 , Date assigned: 22 April 2014.

A cluster randomised feasibility trial evaluating six-month nutritional interventions in the treatment of malnutrition in care home-dwelling adults: recruitment, data collection and protocol.

BACKGROUND: Protein energy malnutrition predisposes individuals to disease, delays recovery from illness and reduces quality of life. Care home residents are especially vulnerable, with an estimated 30%-42% at risk. There is no internationally agreed protocol for the nutritional treatment of malnutrition in the care home setting. Widely used techniques include food-based intervention and/or the use of prescribed oral nutritional supplements, but a trial comparing the efficacy of interventions is necessary. In order to define outcomes and optimise the design for an adequately powered, low risk of bias cluster randomised controlled trial, a feasibility trial with 6-month intervention is being run, to assess protocol procedures, recruitment and retention rates, consent processes and resident and staff acceptability. METHODS: Trial recruitment began in September 2013 and concluded in December 2013. Six privately run care homes in Solihull, England, were selected to establish feasibility within different care home types. Residents with or at risk of malnutrition with no existing dietetic intervention in place were considered for receipt of the allocated intervention. Randomisation took place at the care home level, using a computer-generated random number list to allocate each home to either a dietetic intervention arm (food-based or prescribed supplements) or the standard care arm, continued for 6 months. Dietetic intervention aimed to increase daily calorie intake by 600 kcal and protein by 20-25 g. RESULTS: The primary outcomes will be trial feasibility and acceptability of trial design and allocated interventions. A range of outcome assessments and data collection tools will be evaluated for feasibility, including change in nutrient intake, anthropometric parameters and patient-centric measures, such as quality of life and self-perceived appetite. CONCLUSIONS: The complexities inherent in care home research has resulted in the under representation of this population in research trials. The results of this feasibility trial will be used to inform the development and design of a future cluster randomised controlled trial to compare food-based intervention with prescribed oral nutritional supplements (ONS) in the treatment of malnutrition within the care home population. TRIAL REGISTRATION: Current Controlled Trials ISRCTN38047922.