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For almost fifteen years, the availability and regulatory acceptance of new approach methodologies (NAMs) to assess the absorption, distribution, metabolism and excretion (ADME/biokinetics) in chemical risk evaluations are a bottleneck. To enhance the field, a team of 24 experts from science, industry, and regulatory bodies, including new generation toxicologists, met at the Lorentz Centre in Leiden, The Netherlands. A range of possibilities for the use of NAMs for biokinetics in risk evaluations were formulated (for example to define species differences and human variation or to perform quantitative in vitro-in vivo extrapolations). To increase the regulatory use and acceptance of NAMs for biokinetics for these ADME considerations within risk evaluations, the development of test guidelines (protocols) and of overarching guidance documents is considered a critical step. To this end, a need for an expert group on biokinetics within the Organisation of Economic Cooperation and Development (OECD) to supervise this process was formulated. The workshop discussions revealed that method development is still required, particularly to adequately capture transporter mediated processes as well as to obtain cell models that reflect the physiology and kinetic characteristics of relevant organs. Developments in the fields of stem cells, organoids and organ-on-a-chip models provide promising tools to meet these research needs in the future.

ADME (absorption, distribution, metabolism, elimination) has rapidly evolved over the past two decades, creating a unique interdisciplinary interface between medicinal chemists, biologists, formulators, toxicologists, clinicians, and regulators across industries, but has advanced most rapidly in the pharmaceutical industry. The implementation of ADME profiling of drug candidates, in conjunction with biological efficacy and safety optimization, has dramatically reduced pharmacokinetic drug failures in clinical trials and has become a lingua franca between disciplines that are involved in drug development. This article briefly reviews the basics and current state-of-the-art of ADME and the major lessons from the pharmaceutical industry on its efficient use, points out the importance of defining ADME properties leading to toxicity across industries for safety and toxicity prediction of chemicals, and raises the issues of quality, reliability, and reproducibility of tests and inclusion of ADME under the umbrella of evidence-based toxicology. Increasingly, in vitro results are used to inform ADME assessments and computer modeling. The aspects of kinetics of substances in cellular models themselves, however, are still too often neglected. ADME information will play a critical role in establishing quantitative in vitro to in vivo extrapolations (QIVIVE), integrated testing strategies, and systems toxicology approaches.

In April 2013 the mouse antibody serum neutralization test (SNT) was formally incorporated into European Pharmacopoeia monograph 0451 for potency testing of inactivated veterinary rabies vaccines. The SNT is designed to replace the highly variable and pain and distress causing NIH mouse rabies challenge assay. The adoption of the SNT meets the European ambition (i.e., EC and CoE) to replace, reduce and/or refine laboratory animal testing. However, regulatory acceptance and use of 3R models, such as the SNT, remains challenging. This paper aims at clarifying the process of acceptance and use of the SNT. For this purpose it reconstructs the process and reveals barriers and drivers that have been observed by involved stakeholders to have played a role. In addition it extracts lessons to stimulate regulatory acceptance in similar future processes. The incorporation of the SNT into the monographs went relatively quick due to a thorough test development and pre-validation phase, commitment and cooperation of relevant stakeholders and a strong project coordination of the international validation study. The test was developed by the Paul Ehrlich Institut; a leading European OMCLs. This facilitated its European regulatory use. The use by industry is in a critical phase. At this stage product specific validation and the question whether the SNT will be accepted outside Europe are important influencing factors.

The role that in vitro systems can play in toxicological risk assessment is determined by the appropriateness of the chosen methods, with respect to the way in which in vitro data can be extrapolated to the in vivo situation. This report presents the results of a workshop aimed at better defining the use of in vitro-derived biomarkers of toxicity (BoT) and determining the place these data can have in human risk assessment. As a result, a conceptual framework is presented for the incorporation of in vitro-derived toxicity data into the risk assessment process. The selection of BoT takes into account that they need to distinguish adverse and adaptive changes in cells. The framework defines the place of in vitro systems in the context of data on exposure, structural and physico-chemical properties, and toxicodynamic and biokinetic modeling. It outlines the determination of a proper point-of-departure (PoD) for in vitro-in vivo extrapolation, allowing implementation in risk assessment procedures. A BoT will need to take into account both the dynamics and the kinetics of the compound in the in vitro systems. For the implementation of the proposed framework it will be necessary to collect and collate data from existing literature and new in vitro test systems, as well as to categorize biomarkers of toxicity and their relation to pathways-of-toxicity. Moreover, data selection and integration need to be driven by their usefulness in a quantitative in vitro-in vivo extrapolation (QIVIVE).

The importance placed on risk avoidance in our society has resulted in a broad range of regulations intended to guarantee safety of products such as pharmaceuticals and chemicals. Many of these regulations rely on animal tests. As a result, about 25% of the animal experiments in Europe are done for regulatory purposes. There are many initiatives that aim to replace, reduce, or refine laboratory animal use, but the regulatory acceptance and use of 3R models lags behind. The central question of this study is: "Which variables influence the regulatory acceptance and use of 3R models and in what way?" Regulatory acceptance is seen as one of the biggest hurdles 3R models face, but the rationale behind this is still underexplored. This study is an approach to filling that gap by combining opinions from experts in the field with literature on technology acceptance and risk regulation, resulting in a model of the variables that determine the process of the regulatory acceptance and use of 3R models.

The European cosmetics legislation foresees a review in 2011 and possible postponement of the 2013 marketing ban to enforce the testing ban for systemic and repeated-dose animal tests. For this purpose, a 119-page report commissioned by the European Commission was published recently. Here, a group of 17 independent experts from the US, Europe, and Japan was brought together to evaluate the report. The expert panel strongly endorsed the report and its conclusions. A number of important options not considered were identified; these do not, however, affect the overall conclusions regarding the current lack of availability of a full replacement, especially for the areas of repeated dose toxicity, carcinogenicity testing, and reproductive toxicity, though a roadmap for change is emerging. However, some of these options may provide adequate data for replacement of some animal studies in the near future pending validation. Various recommendations expand the original report. The reviewers agree with the report that there is greater promise in the short term for the areas of sensitization and toxicokinetics. Additional opportunities lie in more global collaborations and the inclusion of other industry sectors.

Approximately 30% of animal use within the European Union (EU) is done to meet regulatory requirements. The tests are often repetitive in nature and may cause severe suffering, due to the procedures used and to rigidly predefined end points. In addition, product evaluation procedures often take long and are very expensive. Over the last decades the heavy reliance on animal experimentation in this area has met serious objections, both ethical and economical in nature. This study describes obstacles and opportunities to implement the 3Rs in regulatory animal testing. The findings are based primarily on interviews with legislators, regulators, industry, science and animal welfare organisations and reflect shared perceptions of these respondents. In order to increase the application of the 3Rs in regulatory testing a number of technical, political and social obstacles must be overcome. This study offers insight into the persistent character of regulatory animal testing and can function as a starting point for further discussion on how to tackle these problems. To this end, several recommendations are made ranging from strategic test approaches and data sharing to strengthening the policy network and improving communication between 3Rs experts and regulators. The study is an initiative of the national project group "Regulatory Animal Testing", which consists of a group of Dutch experts on animal testing working for a variety of organisations in the field.1 They felt the need for cooperation to initiate a discussion at relevant levels and to identify possible solutions in order to implement the objectives of the three R's in testing for regulatory purposes without loss of scrutiny in safety and/or efficacy evaluation needed for product release.