Nephrectomized and Hepatectomized Animal Models as Tools in Preclinical Pharmacokinetics

Early understanding of the pharmacokinetics and metabolic patterns of new drug candidates is essential for selection of optimal candidates to move further in to the drug development process. In vitro methodologies can be used to investigate metabolic patterns, but in general, they lack several aspects of the whole‐body physiology. In contrast, the complexity of intact animals does not necessarily allow individual processes to be identified. Animal models lacking a major excretion organ can be used to investigate these individual metabolic processes. Animal models of nephrectomy and hepatectomy have considerable potential as tools in preclinical pharmacokinetics to assess organs of importance for drug clearance and thereby knowledge of potential metabolic processes to manipulate to improve pharmacokinetic properties of the molecules. Detailed knowledge of anatomy and surgical techniques is crucial to successfully establish the models, and a well‐balanced anaesthesia and adequate monitoring of the animals are also of major importance. An obvious drawback of animal models lacking an organ is the disruption of normal homoeostasis and the induction of dramatic and ultimately mortal systemic changes in the animals. Refining of the surgical techniques and the post‐operative supportive care of the animals can increase the value of these models by minimizing the systemic changes induced, and thorough validation of nephrectomy and hepatectomy models is needed before use of such models as a tool in preclinical pharmacokinetics. The present MiniReview discusses pros and cons of the available techniques associated with establishing nephrectomy and hepatectomy models.     

New approaches in psychiatric drug development

Numerous novel neuroscience-based drug targets have been identified in recent years. However, it remains unclear how these targets relate to the expression of symptoms in central nervous system (CNS) disorders in general and psychiatric disorders in particular. To discuss this issue, a New Frontiers Meetings of European College of Neuropsychopharmacology (ECNP) was organized to address the challenges in translational neuroscience research that are impeding the effective development of new treatments.The main aim of this meeting was to discuss scientific insights, concepts and methodologies in order to improve drug development for psychiatric disorders. The meeting was designed to bring together stakeholders from academia, pharmaceutical industry, and regulatory agencies.Here we provide a synopsis of the proceedings from the meeting entitled ‘New approaches to psychiatric drug development’. New views on psychiatric drug development were presented to address the challenges and pitfalls as identified by the different stakeholders. The general conclusion of the meeting was that drug discovery could be stimulated by designing new classification and sensitive assessment tools for psychiatric disorders, which bear closer relationships to neuropharmacological and neuroscientific developments. This is in line with the vision of precision psychiatry in which patients are clustered, not merely on symptoms, but primarily on biological phenotypes that represent pathophysiological relevant and ‘drugable’ processes. To achieve these goals, a closer collaboration between all stakeholders in early stages of development is essential to define the research criteria together and to reach consensus on new quantitative biological methodologies and etiology-directed treatments.     

Multifunctional neuroprotective drugs targeting monoamine oxidase inhibition,iron chelation,adenosine receptors,and cholinergic and glutamatergic action for neurodegenerative diseases

A new paradigm is emerging in the targeting of multiple disease aetiologies that collectively lead to neurodegenerative disorders such as Parkinson’s disease, Alzheimer’s disease, post-stroke neurodegeneration and others. This paradigm challenges the widely held assumption that ‘silver bullet’ agents are superior to ‘dirty drugs’ when it comes to drug therapy. Accumulating evidence in the literature suggests that many neurodegenerative diseases have multiple mechanisms in their aetiologies, thus suggesting that a drug with at least two mechanisms of action targeted at multiple aetiologies of the same disease may offer more therapeutic benefit in certain disorders compared with a drug that only targets one disease aetiology. This review offers a synopsis of therapeutic strategies and novel investigative drugs developed in the authors’ own and other laboratories that modulate multiple disease targets associated with neurodegenerative diseases.     

Evolving ‘-omics’ technologies in the drug development process

The strength of the ‘-omics’ technologies lies in their ability to monitor the activity of biomolecules in a large-scale, high-throughput fashion shortening the overall time needed for the discovery of a new drug. Recent advances in technology have resulted in a higher reproducibility and enhanced sensitivity, thus allowing for a more precise deciphering of a pathologic process. However, because of strict standardization criteria that demands strong financial support and the availability of highly specialized experts, the importance of dedicated core facilities or specialized units becomes central. Today, the ‘omics’ approach in biomedicine has become more pathway-oriented and is complemented by several other experimental approaches, data analyses, pathway informatics, literature mining and mathematical modeling processes, all of which are contained within systems biology. The authors believe that systems biology is an integrated approach that can offer a solution to some of the major bottlenecks in drug discovery and can foster target identification, allowing the drug to target molecules relevant to disease pathways. In this perspective, the authors touch on the present state of the mainstream ‘-omics’ technologies already in use in drug discovery as well as their shortcomings and perspectives for future applications.     

Updates on the treatment of gout,including a review of updated treatment guidelines and use of small molecule therapies for difficult-to-treat gout and gout flares

Introduction: Gout is a rheumatologic condition associated with elevated serum uric acid levels and deposition of monosodium urate crystals in joints and soft tissues.

Areas covered: In this article, we describe the role of currently available drug therapies for managing acute gout flares and used in reducing serum urate levels. Further, we explore the role of novel small molecular therapies and biologic agents in the treatment of refractory or severe gout symptoms. A literature search of MEDLINE and MEDLINE In-Process & Other Non-Indexed Citations Databases (1996-June 2017) was conducted utilizing the key words ‘gout’, ‘interleukin-1 inhibitors’, ‘acute gout’, ‘gout treatment’, ‘urate lowering therapies’, ‘hyperuricemia’, ‘colchicine’, ‘pegloticase’, ‘lesinurad’, ‘xanthine oxidase’, ‘xanthine oxidase inhibitors’, ‘allopurinol’, ‘febuxostat’, ‘uricosurics’, ‘probenecid’, and ‘benzbromarone’. All published articles regarding therapeutic management of gout and hyperuricemia were evaluated. References of selected articles, data from poster presentations, and abstract publications were additionally reviewed.

Expert opinion: Numerous therapies are currently available to managing acute gout flares and for lowering serum urate levels; advances in the understanding of the pathophysiology of this disorder has led to the emergence of targeted therapies and novel biologic preparations currently in development which may improve the clinical management of severe or refractory cases of disease that fail to respond to traditional therapies.     

Mapping of Allosteric Druggable Sites in Activation‐Associated Conformers of the M2 Muscarinic Receptor

G‐protein‐coupled receptors (GPCRs) are key cellular signaling proteins and have been targeted by approximately 30–40% of marketed drugs for treating many human diseases including cancer and heart failure. Recently, we directly observed activation of the M2 muscarinic receptor through long‐timescale accelerated molecular dynamics (aMD) simulation, which revealed distinct inactive, intermediate and active conformers of the receptor. Here, FTMAP is applied to search for ‘hot spots’ in these activation‐associated conformers using a library of 16 organic probe molecules that represent fragments of potential drugs. Seven allosteric (non‐orthosteric) binding sites are identified in the M2 receptor through the FTMAP analysis. These sites are distributed in the solvent‐exposed extracellular and intracellular mouth regions, as well as the lipid‐exposed pockets formed by the transmembrane α helices TM3‐TM4, TM5‐TM6 and TM7‐TM1/TM2. They serve as promising target sites for designing novel allosteric modulators as receptor‐selective drugs.     

Genetically modified animals in pharmacological research: future trends.

The recognition of molecular control elements which govern cell and organ function is essential for the development of novel drug therapies and for an understanding of drug actions. Thus, a major interest is focused on methodologies which permit the identification of novel control elements. This is of particular relevance for the identification of drug targets, the distinction of target isoforms, the differentiation of signalling pathways, the generation of disease models and toxicological testing. In this review, we discuss different classes of genetically modified animals and their potential to elucidate biological processes relevant for pharmacological research including functional genomics. Techniques which permit the time- and tissue-specific inducible regulation of gene expression present an important methodological advance.     

Triazole: A Promising Antitubercular Agent

Tuberculosis is a contagious disease with comparatively high mortality worldwide. The statistics shows that around three million people throughout the world die annually from tuberculosis and there are around eight million new cases each year, of which developing countries showed major share. Therefore, the discovery and development of effective antituberculosis drugs with novel mechanism of action have become an insistent task for infectious diseases research programs. The literature reveals that, heterocyclic moieties have drawn attention of the chemists, pharmacologists, microbiologists, and other researchers owing to its indomitable biological potential as anti‐infective agents. Among heterocyclic compounds, triazole (1,2,3‐triazole/1,2,4‐triazole) nucleus is one of the most important and well‐known heterocycles, which is a common and integral feature of a variety of natural products and medicinal agents. Triazole core is considered as a privileged structure in medicinal chemistry and is widely used as ‘parental’ compounds to synthesize molecules with medical benefits, especially with infection‐related activities. In the present review, we have collated published reports on this versatile core to provide an insight so that its complete therapeutic potential can be utilized for the treatment of tuberculosis. This review also explores triazole as a potential targeted core moiety against tuberculosis and various research ongoing worldwide. It is hoped that this review will be helpful for new thoughts in the quest for rational designs of more active and less toxic triazole‐based antituberculosis drugs.     

Targeting the PTPome in human disease

Protein tyrosine phosphatases (PTPs) play vital roles in numerous cellular processes and are implicated in a growing number of human diseases, ranging from cancer to cardiovascular, immunological, infectious, neurological and metabolic diseases. There are at least 107 genes in the human genome, collectively referred to as the human ‘PTPome’. Here the authors review the involvement of PTPs in human disease, discuss their potential as drug targets, and current efforts to develop PTP inhibitors for the treatment of human disease. Finally, the authors present their view of the future for PTPs as drug targets.     

Advances in nasal drug delivery through tight junction technology

New approaches for enhancing intranasal drug delivery based on recent discoveries on the molecular biology of tight junctions (TJ) are significantly improving the bioavailability of ‘non-Lipinsky’ small molecules, and peptide, protein and oligonucleotide drugs. As knowledge of the structure and function of the TJ has developed, so has the ability to identify mechanism-based TJ modulators using high-throughput molecular biology-based screening methods. The present review focuses on recent developments on the TJ protein complex as a lipid raft-like membrane microdomain, the emerging role of unique endocytic pathways in regulating TJ dynamics, and the utility of techniques such as RNA interference and phage display to study TJ components and identify novel peptides and related molecules that can modulate their function. Experimental and statistical methodologies used for the identification of new classes of TJ modulators are described, which are capable of reversibly opening TJ barriers with broad potential to significantly improve intranasal and, eventually, oral drug delivery. The development of an advanced intranasal formulation for the obesity therapeutic PYY_3-36, the endogenous Y2 receptor agonist is also reviewed.     

Systematic review: the epidemiology and natural history of non-alcoholic fatty liver disease and non-alcoholic steatohepatitis in adults

Aliment Pharmacol Ther 2011; 34: 274–285

Summary

Background Non‐alcoholic fatty liver disease (NAFLD) is a common cause of chronic liver disease, and its worldwide prevalence continues to increase with the growing obesity epidemic. This study assesses the epidemiology of NAFLD in adults based on clinical literature published over the past 30 years. Aim To review epidemiology and natural history of non‐alcoholic fatty liver disease and non‐alcoholic steatohepatitis in adults based on clinical literature published over the past 30 years. Methods An in‐depth search of PubMed (1980–2010) was based on five search terms: ‘non‐alcoholic fatty liver disease’ OR ‘non‐alcoholic steatohepatitis’ OR ‘fatty liver’ OR ‘steatosis’ AND ‘incidence’ [MeSH Terms] OR ‘prevalence’ [MeSH Terms] OR ‘natural history’. Studies of paediatric cohorts were excluded. Articles were categorised by topic and summarised, noting generalisations concerning their content. Results Four study categories included NAFLD incidence, prevalence, risk factors and natural history. Studies related to NAFLD prevalence and incidence indicate that the diagnosis is heterogeneous and relies on a variety of assessment tools, including liver biopsy, radiological tests such as ultrasonography, and blood testing such as liver enzymes. The prevalence of NAFLD is highest in populations with pre‐existing metabolic conditions such as obesity and type II diabetes. Many studies investigating the natural history of NAFLD verify the progression from NASH to advanced fibrosis and hepatocellular carcinoma. Conclusions Non‐alcoholic fatty liver disease is the most common cause of elevated liver enzymes. Within the NAFLD spectrum, only NASH progresses to cirrhosis and hepatocellular carcinoma. With the growing epidemic of obesity, the prevalence and impact of NAFLD continues to increase, making NASH potentially the most common cause of advanced liver disease in coming decades.     

Current pharmacotherapy for inflammatory bowel disease

Ulcerative colitis (UC) and Crohn’s disease (CD), collectively termed inflammatory bowel disease (IBD), are chronic spontaneously relapsing enteropathies of unknown aetiology. Pharmacotherapy for IBD has essentially been unchanged for over twenty years, with therapy based around 5-aminosalicylic acid (5-ASA) preparations, corticosteroids, antibiotics and immunosuppression. Much of the controversy surrounding optimal use of these drugs in IBD arises as a consequence of methodological deficiencies in many of the early trials combined with the difficulty in consistent patient selection due to the heterogeneous nature of both UC and CD. More recently, well-designed clinical trials have attempted to provide an ‘evidence based’ approach to managing IBD which, in time, will allow optimisation of current therapies and accurate evaluation of novel agents. Over the past two decades, improved research methodology has considerably increased our molecular understanding of the aetiopathogenesis of IBD which has ultimately lead to the development of specific mediator directed or ‘designer’ drug therapy for IBD. This review evaluates the literature on current IBD therapy, summarises the important recent studies which have made an impact on clinical practice, and examines the risks and benefits of the novel agents which are currently under investigation in clinical trials of IBD therapy.     

Computational prediction of human drug metabolism

There is an urgent requirement within the pharmaceutical and biotechnology industries, regulatory authorities and academia to improve the success of molecules that are selected for clinical trials. Although absorption, distribution, metabolism, excretion and toxicity (ADME/Tox) properties are some of the many components that contribute to successful drug discovery and development, they represent factors for which we currently have in vitro and in vivo data that can be modelled computationally. Understanding the possible toxicity and the metabolic fate of xenobiotics in the human body is particularly important in early drug discovery. There is, therefore, a need for computational methodologies for uncovering the relationships between the structure and the biological activity of novel molecules. The convergence of numerous technologies, including high-throughput techniques, databases, ADME/Tox modelling and systems biology modelling, is leading to the foundation of systems-ADME/Tox. Results from experiments can be integrated with predictions to globally simulate and understand the likely complete effects of a molecule in humans. The development and early application of major components of MetaDrug (GeneGo, Inc.) software will be described, which includes rule-based metabolite prediction, quantitative structure-activity relationship models for major drug metabolising enzymes, and an extensive database of human protein-xenobiotic interactions. This represents a combined approach to predicting drug metabolism. MetaDrug can be readily used for visualising Phase I and II metabolic pathways, as well as interpreting high-throughput data derived from microarrays as networks of interacting objects. This will ultimately aid in hypothesis generation and the early triaging of molecules likely to have undesirable predicted properties or measured effects on key proteins and cellular functions.     

Discovery of Novel Vascular Endothelial Growth Factor Receptor 2 Inhibitors: A Virtual Screening Approach

A virtual screening approach was performed to develop novel and potent vascular endothelial growth factor receptor 2 inhibitors. The Specs database was filtered by ‘rule of five’, a pharmacophore model, and docking filter. Sixteen molecules were selected for tube formation assay, a naphthalenol group containing molecule, 12 , showed good performance in the study. In the following aortic ring assay and 3‐(4,5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyltetrazolium bromide assay, 12 was discovered to efficiently inhibit angiogenesis and tumor cell growth. It is the first time to discover naphthalenol scaffold as potent vascular endothelial growth factor receptor 2 inhibitors. Thus, a molecular dynamic simulation process was applied to discover key features of 12 in binding to vascular endothelial growth factor receptor 2. Hydrophobic interactions were discovered to play significant role in the ligand–receptor binding.     

Structure‐guided Discovery of a Novel Non‐peptide Inhibitor of Dengue Virus NS2B–NS3 Protease

Dengue fever is a fast emerging epidemic‐prone viral disease caused by dengue virus serotypes 1‐4. NS2B–NS3 protease of dengue virus is a validated target to develop antiviral agents. A major limitation in developing dengue virus protease inhibitors has been the lack of or poor cellular activity. In this work, we extracted and refined a pharmacophore model based on X‐ray crystal structure and predicted binding patterns, followed by a three‐dimensional flexible database filtration. These output molecules were screened according to a docking‐based protocol, leading to the discovery of a compound with novel scaffold and good cell‐based bioactivity that has potential to be further optimized. The discovery of this novel scaffold by combination of in silico methods suggests that structure‐guided drug discovery can lead to the development of potent dengue virus protease inhibitors.     

Review article: the evidence base for interventions used to maintain remission in Crohn's disease

Background Crohn’s disease is characterised by recurrent flare‐ups alternating with periods of remission. A number of interventions are currently used in clinical practice to try and maintain remission in Crohn’s disease but the evidence base for some of them may be questionable. Aim To review the available evidence on interventions, which are currently used to maintain remission in Crohn’s disease. Methods The Cochrane Library and Medline (Pubmed) were searched for level 1 evidence on specific interventions. Search terms included ‘Crohn’s disease or synonyms’, ‘remission or synonyms’ and the names of specific interventions. Results Azathioprine, infliximab and adalimumab are effective at maintaining remission in Crohn’s disease. Natalizumab is also effective, but there are concerns about its potential association with progressive multifocal leukoencephalopathy. Long‐term enteral nutritional supplementation, enteric‐coated omega‐3 fatty acids and intramuscular methotrexate may also be effective but the evidence for these is based on relatively small studies. The available evidence does not support the use of oral 5‐aminosalicylates agents, corticosteroids, anti‐mycobacterial agents, probiotics or ciclosporin as maintenance therapy in Crohn’s disease. Conclusion A better understanding of the evidence base of existing interventions could result in the use of treatments, which are more likely to lead to improved patient outcomes.     

Design,Synthesis, and in vitro antitubercular activity of 1,2,3‐triazolyl‐dihydroquinoline derivatives

In the quest for new active molecules against Mycobacterium tuberculosis, a series of dihydroquinoline derivatives possessing triazolo substituents were efficiently synthesized using click chemistry. The structure of 6l was evidenced by X‐ray crystallographic study. The newly synthesized compounds were evaluated for their in vitro antitubercular activity against Mycobacterium tuberculosis H37Rv (ATCC27294). The compounds 6a , 6g, and 6j (MIC: 3.13 μg/ml) showed promising activity when compared to the first‐line drug such as ethambutol. In addition, the structure and antitubercular activity relationship were further supported by in silico molecular docking studies of the active compounds against 3IVX.PDB (crystal structure of pantothenate synthetase in complex with 2‐(2‐(benzofuran‐2‐ylsulfonylcarbamoyl)‐5‐methoxy‐1H‐indol‐1‐yl)acetic acid).