Integrated testing strategy for the study of the effects of the human pharmaceutical dutasteride on fish

This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University.In recent years, a growing number of human pharmaceuticals have been detected in the aquatic environment, generally at low concentrations (sub-ng/L to low μg/L). These compounds are characterised by highly specific mechanisms of action, high potency and prolonged activity in order to minimise dosing requirements and potential toxicity in patients. Among the various classes of pharmaceuticals, steroids and anti-steroids are widely used, as shown by the analysis of their clinical use carried out at the beginning of this Ph.D. project. Although the amounts used are much lower than the amounts of some other pharmaceuticals (e.g. analgesics), their ability to affect important physiological processes in fish (e.g. reproduction) at very low concentrations (ng/L) suggest that this class of compounds should represent a high priority for ecotoxicological research. In particular, this Ph.D. project addressed the question of whether or not dutasteride, a human pharmaceutical mainly used to treat benign prostatic hyperplasia, may cause adverse effects in the teleost fathead minnow (Pimephales promelas) by inhibiting the activity of both isoforms of 5α-reductase (5αR), the enzyme which convert testosterone into dihydrotestosterone (DHT). The theoretical framework used to guide the design of the experimental studies was based on the combination of several conceptual approaches, including the study of the evolutionary degree of conservation and functionality of the drug target in non-target species, and the cross-species extrapolation of pharmacological and toxicological information generated during pre-clinical and clinical studies in mammals during drug development. The results obtained during the first phase of this Ph.D. project strongly suggested that DHT has a physiological role in the fathead minnow. In fact, 5αRs are evolutionary conserved in this species, 5αRs genes are expressed in tissues such as the testis, and DHT circulates in fathead minnow plasma at concentrations similar to those detected in humans. These findings represented the rationale for testing the effects of dutasteride in the fathead minnow. Dutasteride caused significant adverse effects in all the in vivo studies performed in order to evaluate its potential toxicity on fish, including early life stage and short term reproduction studies, and all the tested life stages were sensitive to the inhibition of 5αRs activity; however, none of the observed adverse effects occurred at concentrations of exposure lower than 32 μg/L (measured concentration). The results also showed that female fish are highly sensitive to disruption of the androgenic pathways, highlighting their utility for the evaluation of potential adverse effects caused by anti-androgens on fish. In conclusion, the results presented in this Thesis suggest that, at present, the potential presence of dutasteride in the environment does not represent a risk to wild fish populations, due to the high concentrations required to elict significant adverse effect (LOEC = 32 μg/L) and the low volume of drug prescribed every year (5.07 kg in UK in 2006). However, the high bioaccumulation factor of dutasteride suggest that further studies should be conducted to elucidate the role played by the bioaccumulation process in the toxicity responses observed in fish.This work is funded by GlaxoSmithKlin

Preliminary data on the influence of rearing temperature on the growth and reproductive status of fathead minnows Pimephales promelas

This article has been made available through the Brunel Open Access Publishing Fund and is available from the specified link - Copyright @ 2011 Brian JV et al.An investigation into the influence of temperature on the growth and reproductive status of the fathead minnow Pimephales promelas revealed that, while there was no clear effect of treatment on sex differentiation, ovarian tissue from female fish reared under the highest temperature regime contained large amounts of undefined tissue containing no germ cells. Furthermore, both male and female fish exhibited differences in length mass, condition and somatic indices, and in the expression of secondary sexual characteristics. The patterns observed are discussed in the context of climate change

Integrated testing strategy for the study of the effects of the human pharmaceutical dutasteride on fish

In recent years, a growing number of human pharmaceuticals have been detected in the aquatic environment, generally at low concentrations (sub-ng/L to low μg/L). These compounds are characterised by highly specific mechanisms of action, high potency and prolonged activity in order to minimise dosing requirements and potential toxicity in patients. Among the various classes of pharmaceuticals, steroids and anti-steroids are widely used, as shown by the analysis of their clinical use carried out at the beginning of this Ph.D. project. Although the amounts used are much lower than the amounts of some other pharmaceuticals (e.g. analgesics), their ability to affect important physiological processes in fish (e.g. reproduction) at very low concentrations (ng/L) suggest that this class of compounds should represent a high priority for ecotoxicological research. In particular, this Ph.D. project addressed the question of whether or not dutasteride, a human pharmaceutical mainly used to treat benign prostatic hyperplasia, may cause adverse effects in the teleost fathead minnow (Pimephales promelas) by inhibiting the activity of both isoforms of 5α-reductase (5αR), the enzyme which convert testosterone into dihydrotestosterone (DHT). The theoretical framework used to guide the design of the experimental studies was based on the combination of several conceptual approaches, including the study of the evolutionary degree of conservation and functionality of the drug target in non-target species, and the cross-species extrapolation of pharmacological and toxicological information generated during pre-clinical and clinical studies in mammals during drug development. The results obtained during the first phase of this Ph.D. project strongly suggested that DHT has a physiological role in the fathead minnow. In fact, 5αRs are evolutionary conserved in this species, 5αRs genes are expressed in tissues such as the testis, and DHT circulates in fathead minnow plasma at concentrations similar to those detected in humans. These findings represented the rationale for testing the effects of dutasteride in the fathead minnow. Dutasteride caused significant adverse effects in all the in vivo studies performed in order to evaluate its potential toxicity on fish, including early life stage and short term reproduction studies, and all the tested life stages were sensitive to the inhibition of 5αRs activity; however, none of the observed adverse effects occurred at concentrations of exposure lower than 32 μg/L (measured concentration). The results also showed that female fish are highly sensitive to disruption of the androgenic pathways, highlighting their utility for the evaluation of potential adverse effects caused by anti-androgens on fish. In conclusion, the results presented in this Thesis suggest that, at present, the potential presence of dutasteride in the environment does not represent a risk to wild fish populations, due to the high concentrations required to elict significant adverse effect (LOEC = 32 μg/L) and the low volume of drug prescribed every year (5.07 kg in UK in 2006). However, the high bioaccumulation factor of dutasteride suggest that further studies should be conducted to elucidate the role played by the bioaccumulation process in the toxicity responses observed in fish.EThOS - Electronic Theses Online ServiceGlaxoSmithKlineGBUnited Kingdo

Environmental Occurrence and Predicted Pharmacological Risk to Freshwater Fish of over 200 Neuroactive Pharmaceuticals in Widespread Use

Data Availability Statement: The data supporting the results presented in this paper can be found in the Supplementary Data file and on the public databases and repositories indicated in the Section 2.Supplementary Materials: The following supporting information can be downloaded at https://www.mdpi.com/article/10.3390/toxics10050233/s1, Supplementary Data File.Copyright © 2022 by the authors. There is a growing concern that neuroactive chemicals released into the environment can perturb wildlife behaviour. Among these chemicals, pharmaceuticals such as antidepressants and anxiolytics have been receiving increasing attention, as they are specifically prescribed to modify behavioural responses. Many laboratory studies have demonstrated that some of these compounds can affect various aspects of the behaviour of a range of aquatic organisms; however, these investigations are focused on a very small set of neuroactive pharmaceuticals, and they often consider one compound at a time. In this study, to better understand the environmental and toxicological dimension of the problem, we considered all pharmaceuticals explicitly intended to modulate the central nervous system (CNS), and we hypothesised that these compounds have higher probability of perturbing animal behaviour. Based on this hypothesis, we used the classification of pharmaceuticals provided by the British National Formulary (based on their clinical applications) and identified 210 different CNS-acting pharmaceuticals prescribed in the UK to treat a variety of CNS-related conditions, including mental health and sleep disorders, dementia, epilepsy, nausea, and pain. The analysis of existing databases revealed that 84 of these compounds were already detected in surface waters worldwide. Using a biological read-across approach based on the extrapolation of clinical data, we predicted that the concentration of 32 of these neuroactive pharmaceuticals in surface waters in England may be high enough to elicit pharmacological effects in wild fish. The ecotoxicological effects of the vast majority of these compounds are currently uncharacterised. Overall, these results highlight the importance of addressing this environmental challenge from a mixture toxicology and systems perspective. The knowledge platform developed in the present study can guide future region-specific prioritisation efforts, inform the design of mixture studies, and foster interdisciplinary efforts aimed at identifying novel approaches to predict and interpret the ecological implications of chemical-induced behaviour disruption.UK Natural Environment Research Council (grant NE/S000100/1) for the ChemPop project

Pharmacology-informed prediction of the risk posed to fish by mixtures of non-steroidal anti-inflammatory drugs (NSAIDs) in the environment

© 2020 The Authors. The presence of non-steroidal anti-inflammatory drugs (NSAIDs) in the aquatic environment has raised concern that chronic exposure to these compounds may cause adverse effects in wild fish populations. This potential scenario has led some stakeholders to advocate a stricter regulation of NSAIDs, especially diclofenac. Considering their global clinical importance for the management of pain and inflammation, any regulation that may affect patient access to NSAIDs will have considerable implications for public health. The current environmental risk assessment of NSAIDs is driven by the results of a limited number of standard toxicity tests and does not take into account mechanistic and pharmacological considerations. Here we present a pharmacology-informed framework that enables the prediction of the risk posed to fish by 25 different NSAIDs and their dynamic mixtures. Using network pharmacology approaches, we demonstrated that these 25 NSAIDs display a significant mechanistic promiscuity that could enhance the risk of target-mediated mixture effects near environmentally relevant concentrations. Integrating NSAIDs pharmacokinetic and pharmacodynamic features, we provide highly specific predictions of the adverse phenotypes associated with exposure to NSAIDs, and we developed a visual multi-scale model to guide the interpretation of the toxicological relevance of any given set of NSAIDs exposure data. Our analysis demonstrated a non-negligible risk posed to fish by NSAID mixtures in situations of high drug use and low dilution of waste-water treatment plant effluents. We anticipate that this predictive framework will support the future regulatory environmental risk assessment of NSAIDs and increase the effectiveness of ecopharmacovigilance strategies. Moreover, it can facilitate the prediction of the toxicological risk posed by mixtures via the implementation of mechanistic considerations and could be readily extended to other classes of chemicals.Biotechnology and Biological Sciences Research Council (BBSRC) Research Grant (BB/P505018/1); AstraZeneca Global Safety, Health and Environment research programme

Testing the translational power of the zebrafish: an inter-species analysis of responses to cardiovascular drugs

The zebrafish is rapidly emerging as a promising alternative in vivo model for the detection of drug-induced cardiovascular effects. Despite its increasing popularity, the ability of this model to inform the drug development process is often limited by the uncertainties around the quantitative relevance of zebrafish responses compared with non-clinical mammalian species and ultimately humans. Here we provide a comparative quantitative analysis of the in vivo cardiovascular responses of zebrafish, rat, dog, and human to three model compounds (propranolol, losartan, and captopril), which act as modulators of two key systems (beta-adrenergic and renin-angiotensin systems) involved in the regulation of cardiovascular functions. We used in vivo imaging techniques to generate novel experimental data of drug-mediated cardiovascular effects in zebrafish larvae. This data was combined with a database of inter-species mammalian responses (i.e. heart rate, blood flow, vessel diameter, stroke volume) extracted from the literature to perform a meta-analysis of effect size and direction across multiple species. In spite of the high heterogeneity of study design parameters, our analysis highlighted that zebrafish and human responses were largely comparable in >80% of drug/endpoint combinations. However, it also revealed a high intra-species variability which, in some cases, prevented a conclusive interpretation of the drug-induced effect. The meta-analysis approach, combined with a suitable data visualization strategy, enabled us to observe of patterns of response that would likely remain undetected with more traditional methods of qualitative comparative analysis. We propose that expanding this approach to larger datasets encompassing multiple drugs and modes-of-action, would enable a rigorous and systematic assessment of the applicability domain of the zebrafish from both a mechanistic and phenotypic standpoint. This will increase the confidence in its application for the early detection of adverse drug reactions in any major organ system.Biotechnology and Biological Sciences Research Counci

Testing the translational power of the zebrafish: An interspecies analysis of responses to cardiovascular drugs.

This is the final version. Available from Frontiers Media via the DOI in this record. DATA AVAILABILITY: All datasets generated for this study are included in the manuscript and the supplementary files.The zebrafish is rapidly emerging as a promising alternative in vivo model for the detection of drug-induced cardiovascular effects. Despite its increasing popularity, the ability of this model to inform the drug development process is often limited by the uncertainties around the quantitative relevance of zebrafish responses compared with nonclinical mammalian species and ultimately humans. In this test of concept study, we provide a comparative quantitative analysis of the in vivo cardiovascular responses of zebrafish, rat, dog, and human to three model compounds (propranolol, losartan, and captopril), which act as modulators of two key systems (beta-adrenergic and renin-angiotensin systems) involved in the regulation of cardiovascular functions. We used in vivo imaging techniques to generate novel experimental data of drug-mediated cardiovascular effects in zebrafish larvae. These data were combined with a database of interspecies mammalian responses (i.e., heart rate, blood flow, vessel diameter, and stroke volume) extracted from the literature to perform a meta-analysis of effect size and direction across multiple species. In spite of the high heterogeneity of study design parameters, our analysis highlighted that zebrafish and human responses were largely comparable in >80% of drug/endpoint combinations. However, it also revealed a high intraspecies variability, which, in some cases, prevented a conclusive interpretation of the drug-induced effect. Despite the shortcomings of our study, the meta-analysis approach, combined with a suitable data visualization strategy, enabled us to observe patterns of response that would likely remain undetected with more traditional methods of qualitative comparative analysis. We propose that expanding this approach to larger datasets encompassing multiple drugs and modes of action would enable a rigorous and systematic assessment of the applicability domain of the zebrafish from both a mechanistic and phenotypic standpoint. This will increase the confidence in its application for the early detection of adverse drug reactions in any major organ system.Biotechnology and Biological Sciences Research CouncilAstraZenec

Anti-anxiety drugs and fish behavior: Establishing the link between internal concentrations of oxazepam and behavioral effects

This is the final published version. Available from Wiley via the DOI in this record.Some of the chemistry data have been provided in the Supplemental Data. The raw data from the behavioral analysis can be provided on contact with the corresponding author ([email protected]).Psychoactive drugs are frequently detected in the aquatic environment. The evolutionary conservation of the molecular targets of these drugs in fish suggests that they may elicit mode of action–mediated effects in fish as they do in humans, and the key open question is at what exposure concentrations these effects might occur. In the present study, the authors investigated the uptake and tissue distribution of the benzodiazepine oxazepam in the fathead minnow (Pimephales promelas) after 28 d of waterborne exposure to 0.8 μg L −1 , 4.7 μg L −1 , and 30.6 μg L −1 . Successively, they explored the relationship between the internal concentrations of oxazepam and the effects on fish exploratory behavior quantified by performing 2 types of behavioral tests, the novel tank diving test and the shelter-seeking test. The highest internal concentrations of oxazepam were found in brain, followed by plasma and liver, whereas muscle presented the lowest values. Average concentrations measured in the plasma of fish from the 3 exposure groups were, respectively, 8.7 ± 5.7 μg L −1 , 30.3 ± 16.1 μg L −1 , and 98.8 ± 72.9 μg L −1 . Significant correlations between plasma and tissue concentrations of oxazepam were found in all 3 groups. Exposure of fish to 30.6 µg L −1 in water produced plasma concentrations within or just below the human therapeutic plasma concentration (H T PC) range in many individuals. Statistically significant behavioral effects in the novel tank diving test were observed in fish exposed to 4.7 μg L −1 . In this group, plasma concentrations of oxazepam were approximately one-third of the lowest H T PC value. No significant effects were observed in fish exposed to the lowest and highest concentrations. The significance of these results is discussed in the context of the species-specific behavior of fathead minnow and existing knowledge of oxazepam pharmacology. Environ Toxicol Chem 2016;35:2782–2790. © 2016 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals, Inc. on behalf of SETAC.Brunel University (London, UK)Spanish Ministry of Economy and CompetitivenessEconomy and Knowledge Department of the Catalan governmen

Are synthetic glucocorticoids in the aquatic environment a risk to fish?

This is the final version. Available from Elsevier via the DOI in this record. The glucocorticosteroid, or glucocorticoid (GC), system is largely conserved across vertebrates and plays a central role in numerous vital physiological processes including bone development, immunomodulation, and modification of glucose metabolism and the induction of stress-related behaviours. As a result of their wide-ranging actions, synthetic GCs are widely prescribed for numerous human and veterinary therapeutic purposes and consequently have been detected extensively within the aquatic environment. Synthetic GCs designed for humans are pharmacologically active in non-mammalian vertebrates, including fish, however they are generally detected in surface waters at low (ng/L) concentrations. In this review, we assess the potential environmental risk of synthetic GCs to fish by comparing available experimental data and effect levels in fish with those in mammals. We found the majority of compounds were predicted to have insignificant risk to fish, however some compounds were predicted to be of moderate and high risk to fish, although the dataset of compounds used for this analysis was small. Given the common mode of action and high level of inter-species target conservation exhibited amongst the GCs, we also give due consideration to the potential for mixture effects, which may be particularly significant when considering the potential for environmental impact from this class of pharmaceuticals. Finally, we also provide recommendations for further research to more fully understand the potential environmental impact of this relatively understudied group of commonly prescribed human and veterinary drugs.Biotechnology and Biological Sciences Research Council/AstraZenecaBiotechnology and Biological Sciences Research CouncilUniversity of Exete