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Sobrinho CR, Milla BM, Soto-Perez J, Moreira TS, Mulkey DK. Histamine/H1 receptor signaling in the parafacial region increases activity of chemosensitive neurons and respiratory activity in rats. J Neurophysiol 2022; 128:218-228. [PMID: 35704395 DOI: 10.1152/jn.00015.2022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Histaminergic neurons of the tuberomammillary nucleus (TMN) are pH-sensitive and contribute to CO2/H+-dependent behaviors including arousal and respiratory activity. TMN neurons project to several respiratory centers including the ventral parafacial region (pF) where chemosensitive retrotrapezoid (RTN) neurons are located, and since RTN neurons are an important source of CO2/H+-dependent respiratory drive, we wondered whether histamine contributes to RTN chemoreception. To test this, we characterized effects of histamine on mean arterial pressure (MAP) and diaphragm muscle activity (DIAEMG) in urethane-anaesthetized, vagotomized and artificially ventilated male Wistar rats. Unilateral injection of histamine (25 mM) in the pF increased DIAEMG amplitude without changing DIAEMG frequency and MAP. Bilateral pF injections of the H1 receptor antagonist diphenhydramine hydrochloride (DPH; 0.5 mM) decreased baseline DIAEMG amplitude and frequency and MAP. Despite the strong inhibitory effect of DPH on baseline breathing, the hypercapnic ventilatory response was preserved under these experimental conditions. At the cellular level, chemosensitive RTN neurons showed a dose-dependent excitatory response to histamine that was blunted by DPH and mimicked by the H1 receptor agonist 2-pyridylethylamine dihydrochloride (2PYEA) under both control conditions and when fast neurotransmitter receptors are blocked. We also tested effects of 2PYEA in the presence of serotonin, another wake-on neurotransmitter that activates RTN chemoreceptors partly by activation of Gq-coupled receptors. We found the response to 2PYEA was diminished in serotonin, suggesting RTN neurons have a limited capacity to respond to multiple Gq-coupled modulators. These results suggest histamine can modulate breathing at the pF level by a mechanism involving H1 receptors.
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Affiliation(s)
- Cleyton R Sobrinho
- Department of Physiology and Biophysics, Institute of Biomedical Science, University of Sao Paulo, Sao Paulo, Brazil.,Department of Physiology and Neurobiology, University of Connecticut, Storrs, CT, United States
| | - Brenda M Milla
- Department of Physiology and Neurobiology, University of Connecticut, Storrs, CT, United States
| | - Jaseph Soto-Perez
- Department of Physiology and Neurobiology, University of Connecticut, Storrs, CT, United States
| | - Thiago S Moreira
- Department of Physiology and Biophysics, Institute of Biomedical Science, University of Sao Paulo, Sao Paulo, Brazil
| | - Daniel K Mulkey
- Department of Physiology and Neurobiology, University of Connecticut, Storrs, CT, United States
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2
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Assessment of receptor affinities of ophthalmic and systemic agents in dry eye disease. Curr Opin Allergy Clin Immunol 2021; 21:480-485. [PMID: 34387278 DOI: 10.1097/aci.0000000000000773] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
PURPOSE OF REVIEW To explore our current understanding of receptor profiles acted upon by medications used to treat dry eye disease (DED). RECENT FINDINGS Research into histaminic and muscarinic receptor affinities for drugs targeting the ocular surface has not kept up with bench research pertaining to the receptor profile of the ocular surface. These insights are necessary for better evaluation of medications used in DED and other allergic disorders. SUMMARY At the H1 receptor, Ketotifen (pKa = 9.2), pyrilamine (pKa = 9.0), and epinastine (pKa = 8.0) had the highest affinities, whereas ranitidine (pKa = 4.2) and cimetidine (pKa = 4.9) had the lowest. Ketotifen, a second-generation antihistamine, was found to have a pKa of 6.7 at muscarinic receptors which was higher than that of diphenhydramine (pKa = 6.4), a first-generation antihistamine. Additionally, second-generation antihistamines have higher affinity for H3 receptors, which have been linked to urticaria, compared to first-generation. Azelastine, a second-generation, demonstrated significant affinity (pKa = 7.1) at the H3 receptor compared to all other drugs. Antazoline (pKa = 4.4) and diphenhydramine (pKa = 4.6), both first-generation antihistamines, had the lowest affinities for the H3 receptor. These findings raise questions about the use of antihistamines in the treatment of DED and allergic disorders.
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3
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Gaohua L, Miao X, Dou L. Crosstalk of physiological pH and chemical pKa under the umbrella of physiologically based pharmacokinetic modeling of drug absorption, distribution, metabolism, excretion, and toxicity. Expert Opin Drug Metab Toxicol 2021; 17:1103-1124. [PMID: 34253134 DOI: 10.1080/17425255.2021.1951223] [Citation(s) in RCA: 37] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Introduction: Physiological pH and chemical pKa are two sides of the same coin in defining the ionization of a drug in the human body. The Henderson-Hasselbalch equation and pH-partition hypothesis form the theoretical base to define the impact of pH-pKa crosstalk on drug ionization and thence its absorption, distribution, metabolism, excretion, and toxicity (ADMET).Areas covered: Human physiological pH is not constant, but a diverse, dynamic state regulated by various biological mechanisms, while the chemical pKa is generally a constant defining the acidic dissociation of the drug at various environmental pH. Works on pH-pKa crosstalk are scattered in the literature, despite its significant contributions to drug pharmacokinetics, pharmacodynamics, safety, and toxicity. In particular, its impacts on drug ADMET have not been effectively linked to the physiologically based pharmacokinetic (PBPK) modeling and simulation, a powerful tool increasingly used in model-informed drug development (MIDD).Expert opinion: Lacking a full consideration of the interactions of physiological pH and chemical pKa in a PBPK model limits scientists' capability in mechanistically describing the drug ADMET. This mini-review compiled literature knowledge on pH-pKa crosstalk and its impacts on drug ADMET, from the viewpoint of PBPK modeling, to pave the way to a systematic incorporation of pH-pKa crosstalk into PBPK modeling and simulation.
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Affiliation(s)
- Lu Gaohua
- Research & Early Development, Princeton, New Jersey, USA
| | - Xiusheng Miao
- Drug Metabolism and Pharmacokinetics, GlaxoSmithKline, Collegeville, Pennsylvania, USA
| | - Liu Dou
- School of Pharmaceutical Sciences (Shenzhen), Sun Yat-sen University, Guangzhou, Guangdong, China
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4
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Porteus CS, Roggatz CC, Velez Z, Hardege JD, Hubbard PC. Acidification can directly affect olfaction in marine organisms. J Exp Biol 2021; 224:270986. [PMID: 34310682 DOI: 10.1242/jeb.237941] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
In the past decade, many studies have investigated the effects of low pH/high CO2 as a proxy for ocean acidification on olfactory-mediated behaviours of marine organisms. The effects of ocean acidification on the behaviour of fish vary from very large to none at all, and most of the maladaptive behaviours observed have been attributed to changes in acid-base regulation, leading to changes in ion distribution over neural membranes, and consequently affecting the functioning of gamma-aminobutyric acid-mediated (GABAergic) neurotransmission. Here, we highlight a possible additional mechanism by which ocean acidification might directly affect olfaction in marine fish and invertebrates. We propose that a decrease in pH can directly affect the protonation, and thereby, 3D conformation and charge distribution of odorants and/or their receptors in the olfactory organs of aquatic animals. This can sometimes enhance signalling, but most of the time the affinity of odorants for their receptors is reduced in high CO2/low pH; therefore, the activity of olfactory receptor neurons decreases as measured using electrophysiology. The reduced signal reception would translate into reduced activation of the olfactory bulb neurons, which are responsible for processing olfactory information in the brain. Over longer exposures of days to weeks, changes in gene expression in the olfactory receptors and olfactory bulb neurons cause these neurons to become less active, exacerbating the problem. A change in olfactory system functioning leads to inappropriate behavioural responses to odorants. We discuss gaps in the literature and suggest some changes to experimental design in order to improve our understanding of the underlying mechanisms and their effects on the associated behaviours to resolve some current controversy in the field regarding the extent of the effects of ocean acidification on marine fish.
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Affiliation(s)
- Cosima S Porteus
- Cell and Systems Biology, University of Toronto, 25 Harbour St, Toronto, ON, M5S 3G5, Canada.,Department of Biological Sciences, University of Toronto Scarborough, 1265 Military Trail, Toronto, Ontario, M1C 1A4, Canada
| | - Christina C Roggatz
- Energy and Environment Institute, University of Hull, Cottingham Road, Hull, HU6 7RX, United Kingdom
| | - Zelia Velez
- Centro de Ciências do Mar do Algarve, Universidade do Algarve, Campus de Gambelas, 8005-139, Faro, Portugal
| | - Jörg D Hardege
- Department of Biological and Marine Sciences, University of Hull, Cottingham Road, Hull, HU6 7RX, United Kingdom
| | - Peter C Hubbard
- Centro de Ciências do Mar do Algarve, Universidade do Algarve, Campus de Gambelas, 8005-139, Faro, Portugal
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5
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Ocean Acidification Amplifies the Olfactory Response to 2-Phenylethylamine: Altered Cue Reception as a Mechanistic Pathway? J Chem Ecol 2021; 47:859-876. [PMID: 34014453 PMCID: PMC8613125 DOI: 10.1007/s10886-021-01276-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2020] [Revised: 03/25/2021] [Accepted: 04/13/2021] [Indexed: 12/19/2022]
Abstract
With carbon dioxide (CO2) levels rising dramatically, climate change threatens marine environments. Due to increasing CO2 concentrations in the ocean, pH levels are expected to drop by 0.4 units by the end of the century. There is an urgent need to understand the impact of ocean acidification on chemical-ecological processes. To date, the extent and mechanisms by which the decreasing ocean pH influences chemical communication are unclear. Combining behaviour assays with computational chemistry, we explore the function of the predator related cue 2-phenylethylamine (PEA) for hermit crabs (Pagurus bernhardus) in current and end-of-the-century oceanic pH. Living in intertidal environments, hermit crabs face large pH fluctuations in their current habitat in addition to climate-change related ocean acidification. We demonstrate that the dietary predator cue PEA for mammals and sea lampreys is an attractant for hermit crabs, with the potency of the cue increasing with decreasing pH levels. In order to explain this increased potency, we assess changes to PEA’s conformational and charge-related properties as one potential mechanistic pathway. Using quantum chemical calculations validated by NMR spectroscopy, we characterise the different protonation states of PEA in water. We show how protonation of PEA could affect receptor-ligand binding, using a possible model receptor for PEA (human TAAR1). Investigating potential mechanisms of pH-dependent effects on olfactory perception of PEA and the respective behavioural response, our study advances the understanding of how ocean acidification interferes with the sense of smell and thereby might impact essential ecological interactions in marine ecosystems.
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6
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Wang Z, Bosma R, Kuhne S, van den Bor J, Garabitian W, Vischer HF, Wijtmans M, Leurs R, de Esch IJ. Exploring the Effect of Cyclization of Histamine H 1 Receptor Antagonists on Ligand Binding Kinetics. ACS OMEGA 2021; 6:12755-12768. [PMID: 34056427 PMCID: PMC8154229 DOI: 10.1021/acsomega.0c06358] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/28/2021] [Accepted: 04/16/2021] [Indexed: 06/12/2023]
Abstract
There is an increasing interest in guiding hit optimization by considering the target binding kinetics of ligands. However, compared to conventional structure-activity relationships, structure-kinetics relationships have not been as thoroughly explored, even for well-studied archetypical drug targets such as the histamine H1 receptor (H1R), a member of the family A G-protein coupled receptor. In this study, we show that the binding kinetics of H1R antagonists at the H1R is dependent on the cyclicity of both the aromatic head group and the amine moiety of H1R ligands, the chemotypes that are characteristic for the first-generation H1R antagonists. Fusing the two aromatic rings of H1R ligands into one tricyclic aromatic head group prolongs the H1R residence time for benchmark H1R ligands as well as for tailored synthetic analogues. The effect of constraining the aromatic rings and the basic amines is systematically explored, leading to a coherent series and detailed discussions of structure-kinetics relationships. This study shows that cyclicity has a pronounced effect on the binding kinetics.
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Affiliation(s)
| | | | | | - Jelle van den Bor
- Amsterdam Institute of Molecular
and Life Sciences (AIMMS), Division of Medicinal Chemistry, Faculty
of Science, Vrije Universiteit Amsterdam, De Boelelaan 1108, 1081 HZ Amsterdam, The Netherlands
| | - Wrej Garabitian
- Amsterdam Institute of Molecular
and Life Sciences (AIMMS), Division of Medicinal Chemistry, Faculty
of Science, Vrije Universiteit Amsterdam, De Boelelaan 1108, 1081 HZ Amsterdam, The Netherlands
| | - Henry F. Vischer
- Amsterdam Institute of Molecular
and Life Sciences (AIMMS), Division of Medicinal Chemistry, Faculty
of Science, Vrije Universiteit Amsterdam, De Boelelaan 1108, 1081 HZ Amsterdam, The Netherlands
| | - Maikel Wijtmans
- Amsterdam Institute of Molecular
and Life Sciences (AIMMS), Division of Medicinal Chemistry, Faculty
of Science, Vrije Universiteit Amsterdam, De Boelelaan 1108, 1081 HZ Amsterdam, The Netherlands
| | - Rob Leurs
- Amsterdam Institute of Molecular
and Life Sciences (AIMMS), Division of Medicinal Chemistry, Faculty
of Science, Vrije Universiteit Amsterdam, De Boelelaan 1108, 1081 HZ Amsterdam, The Netherlands
| | - Iwan J.P. de Esch
- Amsterdam Institute of Molecular
and Life Sciences (AIMMS), Division of Medicinal Chemistry, Faculty
of Science, Vrije Universiteit Amsterdam, De Boelelaan 1108, 1081 HZ Amsterdam, The Netherlands
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7
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van der Velden WJC, Heitman LH, Rosenkilde MM. Perspective: Implications of Ligand-Receptor Binding Kinetics for Therapeutic Targeting of G Protein-Coupled Receptors. ACS Pharmacol Transl Sci 2020; 3:179-189. [PMID: 32296761 DOI: 10.1021/acsptsci.0c00012] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2020] [Indexed: 12/16/2022]
Abstract
The concept of ligand-receptor binding kinetics has been broadly applied in drug development pipelines focusing on G protein-coupled receptors (GPCRs). The ligand residence time (RT) for a receptor describes how long a ligand-receptor complex exists, and is defined as the reciprocal of the dissociation rate constant (k off). RT has turned out to be a valuable parameter for GPCR researchers focusing on drug development as a good predictor of in vivo efficacy. The positive correlation between RT and in vivo efficacy has been established for several drugs targeting class A GPCRs (e.g., the neurokinin-1 receptor (NK1R), the β2 adrenergic receptor (β2AR), and the muscarinic 3 receptor (M3R)) and for drugs targeting class B1 (e.g., the glucagon-like peptide 1 receptor (GLP-1R)). Recently, the association rate constant (k on) has gained similar attention as another parameter affecting in vivo efficacy. In the current perspective, we address the importance of studying ligand-receptor binding kinetics for therapeutic targeting of GPCRs, with an emphasis on how binding kinetics can be altered by subtle molecular changes in the ligands and/or the receptors and how such changes affect treatment outcome. Moreover, we speculate on the impact of binding kinetic parameters for functional selectivity and sustained receptor signaling from endosomal compartments; phenomena that have gained increasing interest in attempts to improve therapeutic targeting of GPCRs.
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Affiliation(s)
- Wijnand J C van der Velden
- Laboratory for Molecular Pharmacology, Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen DK 2200, Denmark
| | - Laura H Heitman
- Division of Drug Discovery and Safety, Leiden Academic Centre for Drug Research, Leiden University, Leiden 2333 CC, The Netherlands
| | - Mette M Rosenkilde
- Laboratory for Molecular Pharmacology, Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen DK 2200, Denmark
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8
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Yonekura S, Okamoto Y, Sakurai D, Iinuma T, Sakurai T, Yoneda R, Kurita J, Hanazawa T, Kawasaki Y. Efficacy of Desloratadine and Levocetirizine in Patients with Cedar Pollen-Induced Allergic Rhinitis: A Randomized, Double-Blind Study. Int Arch Allergy Immunol 2019; 180:274-283. [PMID: 31618733 DOI: 10.1159/000503065] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2019] [Accepted: 09/02/2019] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND No comparative study of antihistamines that differ in structural system has been conducted in allergic rhinitis. OBJECTIVE This was a randomized, double-blind, crossover comparative study to verify the efficacy of antihistamines that differ in structural system. METHODS A total of 50 patients with moderate or more severe Japanese cedar pollen-induced allergic rhinitis were randomized to receive either placebo, desloratadine 5 mg (a tricyclic), or levocetirizine 5 mg (a piperazine). One dose of the study drug was orally administered at 9 pm on the day before a pollen exposure test, which was performed for 3 h (9 a.m. to 12 p.m.) to assess symptoms in an environmental challenge chamber (ECC). Nasal and ocular symptoms were compared at an airborne pollen level of 8,000 grains/m3. The primary endpoint was mean total nasal symptom score (TNSS) from 120 to 180 min in the ECC. Subjects with a difference of ≥1 in TNSS between 2 drugs were extracted to the relevant drug-responsive group. RESULTS The difference in TNSS from placebo was -2.42 (p < 0.0001) with levocetirizine and -1.66 (p < 0.01) with desloratadine, showing that both drugs were significantly more effective than placebo in controlling symptoms, but with no statistically significant difference between the 2 drugs. There were 12 subjects in the desloratadine-responsive group and 24 subjects in the levocetirizine-responsive group, with no contributor to response was detected. CONCLUSION Levocetirizine tended to control nasal symptoms more effectively than desloratadine. However, the response to each antihistamine varied among individuals and the predictors to the response are unknown. CLINICAL TRIAL REGISTRATION NUMBER UMIN ID: UMIN000029653.
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Affiliation(s)
- Syuji Yonekura
- Department of Otolaryngology, Head and Neck Surgery, Graduate School of Medicine, Chiba University, Chiba, Japan
| | - Yoshitaka Okamoto
- Department of Otolaryngology, Head and Neck Surgery, Graduate School of Medicine, Chiba University, Chiba, Japan, .,Chiba Rosai Hospital, Chiba, Japan,
| | - Daiju Sakurai
- Department of Otolaryngology, Head and Neck Surgery, Graduate School of Medicine, Chiba University, Chiba, Japan
| | - Tomohisa Iinuma
- Department of Otolaryngology, Head and Neck Surgery, Graduate School of Medicine, Chiba University, Chiba, Japan
| | - Toshioki Sakurai
- Department of Otolaryngology, Head and Neck Surgery, Graduate School of Medicine, Chiba University, Chiba, Japan.,Chiba Cancer Center, Chiba, Japan
| | - Riyo Yoneda
- Department of Otolaryngology, Head and Neck Surgery, Graduate School of Medicine, Chiba University, Chiba, Japan
| | - Junya Kurita
- Department of Otolaryngology, Head and Neck Surgery, Graduate School of Medicine, Chiba University, Chiba, Japan
| | - Toyoyuki Hanazawa
- Department of Otolaryngology, Head and Neck Surgery, Graduate School of Medicine, Chiba University, Chiba, Japan
| | - Yohei Kawasaki
- Biostatistics Section, Clinical Research Center, Chiba University Hospital, Chiba, Japan
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9
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Sykes DA, Jain P, Charlton SJ. Investigating the Influence of Tracer Kinetics on Competition-Kinetic Association Binding Assays: Identifying the Optimal Conditions for Assessing the Kinetics of Low-Affinity Compounds. Mol Pharmacol 2019; 96:378-392. [PMID: 31436538 DOI: 10.1124/mol.119.116764] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2019] [Accepted: 06/22/2019] [Indexed: 12/16/2022] Open
Abstract
An increased appreciation of the importance of optimizing drug-binding kinetics has lead to the development of various techniques for measuring the kinetics of unlabeled compounds. One approach is the competition-association kinetic binding method first described in the 1980s. The kinetic characteristics of the tracer employed greatly affects the reliability of estimated kinetic parameters, a barrier to successfully introducing these kinetic assays earlier in the drug discovery process. Using a modeling and Monte Carlo simulation approach, we identify the optimal tracer characteristics for determining the kinetics of the range of unlabeled ligands typically encountered during the different stages of a drug discovery program (i.e., rapidly dissociating, e.g., k off = 10 minute-1 low-affinity "hits" through to slowly dissociating e.g., k off = 0.01 minute-1 high-affinity "candidates"). For more rapidly dissociating ligands (e.g., k off = 10 minute-1), the key to obtaining accurate kinetic parameters was to employ a tracer with a relatively fast off-rate (e.g., k off = 1 minute-1) or, alternatively, to increase the tracer concentration. Reductions in assay start-time ≤1second and read frequency ≤5 seconds significantly improved the reliability of curve fitting. Timing constraints are largely dictated by the method of detection, its inherent sensitivity (e.g., TR-FRET versus radiometric detection), and the ability to inject samples online. Furthermore, we include data from TR-FRET experiments that validate this simulation approach, confirming its practical utility. These insights into the optimal experimental parameters for development of competition-association assays provide a framework for identifying and testing novel tracers necessary for profiling unlabeled competitors, particularly rapidly dissociating low-affinity competitors.
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Affiliation(s)
- David A Sykes
- School of Life Sciences, Queen's Medical Centre, University of Nottingham, Nottingham, United Kingdom (D.A.S., P.J., S.J.C.); Centre of Membrane and Protein and Receptors (COMPARE), University of Birmingham and University of Nottingham, Midlands, United Kingdom (D.A.S., P.J., S.J.C.); and Excellerate Bioscience Ltd, Discovery Building, BioCity, Nottingham, United Kingdom (S.J.C.)
| | - Palash Jain
- School of Life Sciences, Queen's Medical Centre, University of Nottingham, Nottingham, United Kingdom (D.A.S., P.J., S.J.C.); Centre of Membrane and Protein and Receptors (COMPARE), University of Birmingham and University of Nottingham, Midlands, United Kingdom (D.A.S., P.J., S.J.C.); and Excellerate Bioscience Ltd, Discovery Building, BioCity, Nottingham, United Kingdom (S.J.C.)
| | - Steven J Charlton
- School of Life Sciences, Queen's Medical Centre, University of Nottingham, Nottingham, United Kingdom (D.A.S., P.J., S.J.C.); Centre of Membrane and Protein and Receptors (COMPARE), University of Birmingham and University of Nottingham, Midlands, United Kingdom (D.A.S., P.J., S.J.C.); and Excellerate Bioscience Ltd, Discovery Building, BioCity, Nottingham, United Kingdom (S.J.C.)
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10
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Bosma R, Wang Z, Kooistra AJ, Bushby N, Kuhne S, van den Bor J, Waring MJ, de Graaf C, de Esch IJ, Vischer HF, Sheppard RJ, Wijtmans M, Leurs R. Route to Prolonged Residence Time at the Histamine H 1 Receptor: Growing from Desloratadine to Rupatadine. J Med Chem 2019; 62:6630-6644. [PMID: 31274307 PMCID: PMC6750840 DOI: 10.1021/acs.jmedchem.9b00447] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
![]()
Drug–target
binding kinetics are an important predictor of in vivo drug efficacy,
yet the relationship
between ligand structures and their binding kinetics is often poorly
understood. We show that both rupatadine (1) and desloratadine
(2) have a long residence time at the histamine H1 receptor (H1R). Through development of a [3H]levocetirizine radiolabel, we find that the residence time
of 1 exceeds that of 2 more than 10-fold.
This was further explored with 22 synthesized rupatadine and desloratadine
analogues. Methylene-linked cycloaliphatic or β-branched substitutions
of desloratadine increase the residence time at the H1R,
conveying a longer duration of receptor antagonism. However, cycloaliphatic
substituents directly attached to the piperidine amine (i.e., lacking
the spacer) have decreased binding affinity and residence time compared
to their methylene-linked structural analogues. Guided by docking
studies, steric constraints within the binding pocket are hypothesized
to explain the observed differences in affinity and binding kinetics
between analogues.
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Affiliation(s)
- Reggie Bosma
- Amsterdam Institute for Molecules, Medicines and Systems, Division of Medicinal Chemistry, Faculty of Science , VU University Amsterdam , De Boelelaan 1083 , 1081 HV Amsterdam , The Netherlands
| | - Zhiyong Wang
- Amsterdam Institute for Molecules, Medicines and Systems, Division of Medicinal Chemistry, Faculty of Science , VU University Amsterdam , De Boelelaan 1083 , 1081 HV Amsterdam , The Netherlands
| | - Albert J Kooistra
- Amsterdam Institute for Molecules, Medicines and Systems, Division of Medicinal Chemistry, Faculty of Science , VU University Amsterdam , De Boelelaan 1083 , 1081 HV Amsterdam , The Netherlands
| | - Nick Bushby
- Operations, BioPharmaceuticals R&D , AstraZeneca , Alderley Park , Macclesfield SK10 4TG , United Kingdom
| | - Sebastiaan Kuhne
- Amsterdam Institute for Molecules, Medicines and Systems, Division of Medicinal Chemistry, Faculty of Science , VU University Amsterdam , De Boelelaan 1083 , 1081 HV Amsterdam , The Netherlands
| | - Jelle van den Bor
- Amsterdam Institute for Molecules, Medicines and Systems, Division of Medicinal Chemistry, Faculty of Science , VU University Amsterdam , De Boelelaan 1083 , 1081 HV Amsterdam , The Netherlands
| | - Michael J Waring
- Medicinal Chemistry, Research and Early Development, Oncology R&D , AstraZeneca , Alderley Park , Macclesfield SK10 4TG , United Kingdom
| | - Chris de Graaf
- Amsterdam Institute for Molecules, Medicines and Systems, Division of Medicinal Chemistry, Faculty of Science , VU University Amsterdam , De Boelelaan 1083 , 1081 HV Amsterdam , The Netherlands
| | - Iwan J de Esch
- Amsterdam Institute for Molecules, Medicines and Systems, Division of Medicinal Chemistry, Faculty of Science , VU University Amsterdam , De Boelelaan 1083 , 1081 HV Amsterdam , The Netherlands
| | - Henry F Vischer
- Amsterdam Institute for Molecules, Medicines and Systems, Division of Medicinal Chemistry, Faculty of Science , VU University Amsterdam , De Boelelaan 1083 , 1081 HV Amsterdam , The Netherlands
| | - Robert J Sheppard
- Medicinal Chemistry, Research and Early Development, Cardiovascular, Renal and Metabolism, BioPharmaceuticals R&D , AstraZeneca , Gothenburg 431 50 , Sweden
| | - Maikel Wijtmans
- Amsterdam Institute for Molecules, Medicines and Systems, Division of Medicinal Chemistry, Faculty of Science , VU University Amsterdam , De Boelelaan 1083 , 1081 HV Amsterdam , The Netherlands
| | - Rob Leurs
- Amsterdam Institute for Molecules, Medicines and Systems, Division of Medicinal Chemistry, Faculty of Science , VU University Amsterdam , De Boelelaan 1083 , 1081 HV Amsterdam , The Netherlands
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11
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Probe dependency in the determination of ligand binding kinetics at a prototypical G protein-coupled receptor. Sci Rep 2019; 9:7906. [PMID: 31133718 PMCID: PMC6536503 DOI: 10.1038/s41598-019-44025-5] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2019] [Accepted: 04/25/2019] [Indexed: 01/28/2023] Open
Abstract
Drug-target binding kinetics are suggested to be important parameters for the prediction of in vivo drug-efficacy. For G protein-coupled receptors (GPCRs), the binding kinetics of ligands are typically determined using association binding experiments in competition with radiolabelled probes, followed by analysis with the widely used competitive binding kinetics theory developed by Motulsky and Mahan. Despite this, the influence of the radioligand binding kinetics on the kinetic parameters derived for the ligands tested is often overlooked. To address this, binding rate constants for a series of histamine H1 receptor (H1R) antagonists were determined using radioligands with either slow (low koff) or fast (high koff) dissociation characteristics. A correlation was observed between the probe-specific datasets for the kinetic binding affinities, association rate constants and dissociation rate constants. However, the magnitude and accuracy of the binding rate constant-values was highly dependent on the used radioligand probe. Further analysis using recently developed fluorescent binding methods corroborates the finding that the Motulsky-Mahan methodology is limited by the employed assay conditions. The presented data suggest that kinetic parameters of GPCR ligands depend largely on the characteristics of the probe used and results should therefore be viewed within the experimental context and limitations of the applied methodology.
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12
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Rzemieniec J, Litwa E, Wnuk A, Lason W, Kajta M. Bazedoxifene and raloxifene protect neocortical neurons undergoing hypoxia via targeting ERα and PPAR-γ. Mol Cell Endocrinol 2018; 461:64-78. [PMID: 28859903 DOI: 10.1016/j.mce.2017.08.014] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/28/2017] [Revised: 07/04/2017] [Accepted: 08/28/2017] [Indexed: 12/12/2022]
Abstract
Selective estrogen receptor modulators (SERMs) such as bazedoxifene and raloxifene are recognized to mainly act via estrogen receptors (ERs), but there is no study examining the involvement of PPAR-γ in their actions, especially in neurons undergoing hypoxia. Little is also known about age-dependent actions of the SERMs on neuronal tissue challenged with hypoxia. In this study, bazedoxifene and raloxifene protected neocortical cells against hypoxia at early and later developmental stages. Both SERMs evoked caspase-3-independent neuroprotection and increased protein levels of ERα (66 and 46 kDa isoforms) and PPAR-γ. In addition, bazedoxifene enhanced expression of ERα-regulated Cyp19a1 mRNA. Using double siRNA silencing, for the first time we demonstrated a key role of ERα and PPAR-γ in the neuroprotective action of the SERMs in neocortical neurons undergoing hypoxia. This study provides prospects for the development of a new therapeutic strategies against hypoxic brain injury that selectively target ERα and/or PPAR-γ.
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Affiliation(s)
- J Rzemieniec
- Institute of Pharmacology, Polish Academy of Sciences, Department of Experimental Neuroendocrinology, 31-343 Krakow, Smetna Street 12, Poland
| | - E Litwa
- Institute of Pharmacology, Polish Academy of Sciences, Department of Experimental Neuroendocrinology, 31-343 Krakow, Smetna Street 12, Poland
| | - A Wnuk
- Institute of Pharmacology, Polish Academy of Sciences, Department of Experimental Neuroendocrinology, 31-343 Krakow, Smetna Street 12, Poland
| | - W Lason
- Institute of Pharmacology, Polish Academy of Sciences, Department of Experimental Neuroendocrinology, 31-343 Krakow, Smetna Street 12, Poland
| | - M Kajta
- Institute of Pharmacology, Polish Academy of Sciences, Department of Experimental Neuroendocrinology, 31-343 Krakow, Smetna Street 12, Poland.
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Bosma R, Witt G, Vaas LAI, Josimovic I, Gribbon P, Vischer HF, Gul S, Leurs R. The Target Residence Time of Antihistamines Determines Their Antagonism of the G Protein-Coupled Histamine H1 Receptor. Front Pharmacol 2017; 8:667. [PMID: 29033838 PMCID: PMC5627017 DOI: 10.3389/fphar.2017.00667] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2017] [Accepted: 09/07/2017] [Indexed: 11/13/2022] Open
Abstract
The pharmacodynamics of drug-candidates is often optimized by metrics that describe target binding (Kd or Ki value) or target modulation (IC50). However, these metrics are determined at equilibrium conditions, and consequently information regarding the onset and offset of target engagement and modulation is lost. Drug-target residence time is a measure for the lifetime of the drug-target complex, which has recently been receiving considerable interest, as target residence time is shown to have prognostic value for the in vivo efficacy of several drugs. In this study, we have investigated the relation between the increased residence time of antihistamines at the histamine H1 receptor (H1R) and the duration of effective target-inhibition by these antagonists. Hela cells, endogenously expressing low levels of the H1R, were incubated with a series of antihistamines and dissociation was initiated by washing away the unbound antihistamines. Using a calcium-sensitive fluorescent dye and a label free, dynamic mass redistribution based assay, functional recovery of the H1R responsiveness was measured by stimulating the cells with histamine over time, and the recovery was quantified as the receptor recovery time. Using these assays, we determined that the receptor recovery time for a set of antihistamines differed more than 40-fold and was highly correlated to their H1R residence times, as determined with competitive radioligand binding experiments to the H1R in a cell homogenate. Thus, the receptor recovery time is proposed as a cell-based and physiologically relevant metric for the lead optimization of G protein-coupled receptor antagonists, like the H1R antagonists. Both, label-free or real-time, classical signaling assays allow an efficient and physiologically relevant determination of kinetic properties of drug molecules.
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Affiliation(s)
- Reggie Bosma
- Amsterdam Institute for Molecules, Medicines and Systems, Division of Medicinal Chemistry, Faculty of Science, VU University AmsterdamAmsterdam, Netherlands
| | - Gesa Witt
- Fraunhofer Institute for Molecular Biology and Applied Ecology Screening PortHamburg, Germany
| | - Lea A I Vaas
- Fraunhofer Institute for Molecular Biology and Applied Ecology Screening PortHamburg, Germany
| | - Ivana Josimovic
- Amsterdam Institute for Molecules, Medicines and Systems, Division of Medicinal Chemistry, Faculty of Science, VU University AmsterdamAmsterdam, Netherlands
| | - Philip Gribbon
- Fraunhofer Institute for Molecular Biology and Applied Ecology Screening PortHamburg, Germany
| | - Henry F Vischer
- Amsterdam Institute for Molecules, Medicines and Systems, Division of Medicinal Chemistry, Faculty of Science, VU University AmsterdamAmsterdam, Netherlands
| | - Sheraz Gul
- Fraunhofer Institute for Molecular Biology and Applied Ecology Screening PortHamburg, Germany
| | - Rob Leurs
- Amsterdam Institute for Molecules, Medicines and Systems, Division of Medicinal Chemistry, Faculty of Science, VU University AmsterdamAmsterdam, Netherlands
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Improving the accuracy of high-throughput protein-protein affinity prediction may require better training data. BMC Bioinformatics 2017; 18:102. [PMID: 28361672 PMCID: PMC5374557 DOI: 10.1186/s12859-017-1533-z] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Background One goal of structural biology is to understand how a protein’s 3-dimensional conformation determines its capacity to interact with potential ligands. In the case of small chemical ligands, deconstructing a static protein-ligand complex into its constituent atom-atom interactions is typically sufficient to rapidly predict ligand affinity with high accuracy (>70% correlation between predicted and experimentally-determined affinity), a fact that is exploited to support structure-based drug design. We recently found that protein-DNA/RNA affinity can also be predicted with high accuracy using extensions of existing techniques, but protein-protein affinity could not be predicted with >60% correlation, even when the protein-protein complex was available. Methods X-ray and NMR structures of protein-protein complexes, their associated binding affinities and experimental conditions were obtained from different binding affinity and structural databases. Statistical models were implemented using a generalized linear model framework, including the experimental conditions as new model features. We evaluated the potential for new features to improve affinity prediction models by calculating the Pearson correlation between predicted and experimental binding affinities on the training and test data after model fitting and after cross-validation. Differences in accuracy were assessed using two-sample t test and nonparametric Mann–Whitney U test. Results Here we evaluate a range of potential factors that may interfere with accurate protein-protein affinity prediction. We find that X-ray crystal resolution has the strongest single effect on protein-protein affinity prediction. Limiting our analyses to only high-resolution complexes (≤2.5 Å) increased the correlation between predicted and experimental affinity from 54 to 68% (p = 4.32x10−3). In addition, incorporating information on the experimental conditions under which affinities were measured (pH, temperature and binding assay) had significant effects on prediction accuracy. We also highlight a number of potential errors in large structure-affinity databases, which could affect both model training and accuracy assessment. Conclusions The results suggest that the accuracy of statistical models for protein-protein affinity prediction may be limited by the information present in databases used to train new models. Improving our capacity to integrate large-scale structural and functional information may be required to substantively advance our understanding of the general principles by which a protein’s structure determines its function. Electronic supplementary material The online version of this article (doi:10.1186/s12859-017-1533-z) contains supplementary material, which is available to authorized users.
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15
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Kanamitsu K, Arakawa R, Sugiyama Y, Suhara T, Kusuhara H. Prediction of CNS occupancy of dopamine D2 receptor based on systemic exposure and in vitro experiments. Drug Metab Pharmacokinet 2016; 31:395-404. [DOI: 10.1016/j.dmpk.2016.07.003] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2016] [Revised: 07/14/2016] [Accepted: 07/23/2016] [Indexed: 01/27/2023]
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Kanamitsu K, Nozaki Y, Nagaya Y, Sugiyama Y, Kusuhara H. Quantitative prediction of histamine H1 receptor occupancy by the sedative and non-sedative antagonists in the human central nervous system based on systemic exposure and preclinical data. Drug Metab Pharmacokinet 2016; 32:135-144. [PMID: 28190755 DOI: 10.1016/j.dmpk.2016.11.007] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2016] [Revised: 10/28/2016] [Accepted: 11/07/2016] [Indexed: 12/15/2022]
Abstract
Significant histamine H1 receptor occupation in the central nervous system (CNS) is associated with sedation. Here we examined the time profiles of the H1 receptor occupancy (RO) in the CNS using sedative (diphenhydramine and ketotifen) and non-sedative (bepotastine and olopatadine) antagonists at their therapeutic doses by integrating in vitro and animal data. A pharmacokinetic model was constructed to associate plasma concentrations and receptor binding in the brain. Dissociation and association rate constants with the H1 receptor and plasma and brain unbound fractions were determined in vitro. Passive and active clearances across the blood-brain barrier (BBB) were estimated based on physicochemical properties and microdialysis studies in mice and monkeys. The estimated RO values were comparable with the reported values determined at time to maximum concentration (Tmax) of plasma by positron-emission tomography in humans. The simulation suggested that the predicted maximum ROs by bepotastine and olopatadine were greater than the reported values. Sensitivity analysis showed that active transport across BBB had a significant impact on the RO duration of the H1 antagonists examined. The present study demonstrated that modeling and simulation permits a reasonable RO estimation in the human CNS. Our findings will facilitate the development of CNS-acting drugs.
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Affiliation(s)
- Kayoko Kanamitsu
- Laboratory of Molecular Pharmacokinetics, Graduate School of Pharmaceutical Sciences, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan; Tokushima Research Institute, Otsuka Pharmaceutical Co., Ltd., 463-10 Kagasuno, Kawauchi-cho, Tokushima-shi, Tokushima, 771-0192, Japan
| | - Yoshitane Nozaki
- Drug Metabolism and Pharmacokinetics Tsukuba, Tsukuba Research Laboratories, Eisai Co., Ltd., 5-1-3 Tokodai, Tsukuba-shi, Ibaraki, 300-2635, Japan
| | - Yoko Nagaya
- Drug Metabolism and Pharmacokinetics Tsukuba, Tsukuba Research Laboratories, Eisai Co., Ltd., 5-1-3 Tokodai, Tsukuba-shi, Ibaraki, 300-2635, Japan
| | - Yuichi Sugiyama
- Sugiyama Laboratory, RIKEN Innovation Center, Research Cluster for Innovation, RIKEN, 1-7-22 Suehiro-cho, Tsurumi-ku, Yokohama-shi, Kanagawa, 230-0045, Japan
| | - Hiroyuki Kusuhara
- Laboratory of Molecular Pharmacokinetics, Graduate School of Pharmaceutical Sciences, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan.
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BRET-based β-arrestin2 recruitment to the histamine H1 receptor for investigating antihistamine binding kinetics. Pharmacol Res 2016; 111:679-687. [PMID: 27468652 DOI: 10.1016/j.phrs.2016.07.034] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/30/2016] [Revised: 06/14/2016] [Accepted: 07/24/2016] [Indexed: 01/23/2023]
Abstract
Ligand residence time is thought to be a critical parameter for optimizing the in vivo efficacy of drug candidates. For the histamine H1 receptor (H1R) and other G protein-coupled receptors, the kinetics of ligand binding are typically measured by low throughput radioligand binding experiments using homogenized cell membranes expressing the target receptor. In this study, a real-time proximity assay between H1R and β-arrestin2 in living cells was established to investigate the dynamics of antihistamine binding to the H1R. No receptor reserve was found for the histamine-induced recruitment of β-arrestin2 to the H1R and the transiently recruited β-arrestin2 therefore reflected occupancy of the receptor by histamine. Antihistamines displayed similar kinetic signatures on antagonizing histamine-induced β-arrestin2 recruitment as compared to displacing radioligand binding from the H1R. This homogeneous functional method unambiguously determined the fifty-fold difference in the dissociation rate constant between mepyramine and the long residence time antihistamines levocetirizine and desloratadine.
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18
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Mocking TAM, Bosma R, Rahman SN, Verweij EWE, McNaught-Flores DA, Vischer HF, Leurs R. Molecular Aspects of Histamine Receptors. HISTAMINE RECEPTORS 2016. [DOI: 10.1007/978-3-319-40308-3_1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
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Rzemieniec J, Litwa E, Wnuk A, Lason W, Krzeptowski W, Kajta M. Selective Aryl Hydrocarbon Receptor Modulator 3,3'-Diindolylmethane Impairs AhR and ARNT Signaling and Protects Mouse Neuronal Cells Against Hypoxia. Mol Neurobiol 2015; 53:5591-606. [PMID: 26476840 DOI: 10.1007/s12035-015-9471-0] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2015] [Accepted: 10/01/2015] [Indexed: 01/01/2023]
Abstract
The neuroprotective potential of 3,3'-diindolylmethane (DIM), which is a selective aryl hydrocarbon receptor modulator, has recently been shown in cellular and animal models of Parkinson's disease and lipopolysaccharide-induced inflammation. However, there are no data concerning the protective capacity and mechanisms of DIM action in neuronal cells exposed to hypoxia. The aim of the present study was to investigate the neuroprotective potential of DIM against the hypoxia-induced damage in mouse hippocampal cells in primary cultures, with a particular focus on DIM interactions with the aryl hydrocarbon receptor (AhR), its nuclear translocator ARNT, and estrogen receptor β (ERβ). In the present study, 18 h of hypoxia induced apoptotic processes, in terms of the mitochondrial membrane potential, activation of caspase-3, and fragmentation of cell nuclei. These effects were accompanied by substantial lactate dehydrogenase release and neuronal cell death. The results of the present study demonstrated strong neuroprotective and anti-apoptotic actions of DIM in hippocampal cells exposed to hypoxia. In addition, DIM decreased the Ahr and Arnt mRNA expression and stimulated Erβ mRNA expression level. DIM-induced mRNA alterations were mirrored by changes in protein levels, except for ERβ, as detected by ELISA, Western blotting, and immunofluorescence labeling. We also demonstrated that DIM decreased the expression of AhR-regulated CYP1A1. Using specific siRNAs, we provided evidence that impairment of AhR and ARNT, but not ERβ plays a key role in the neuroprotective action of DIM against hypoxia-induced cell damage. This study may have implication for identifying new agents that could protect neurons against hypoxia by targeting AhR/ARNT signaling.
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Affiliation(s)
- J Rzemieniec
- Department of Experimental Neuroendocrinology, Institute of Pharmacology, Polish Academy of Sciences, 12 Smetna Street, 31-343, Krakow, Poland
| | - E Litwa
- Department of Experimental Neuroendocrinology, Institute of Pharmacology, Polish Academy of Sciences, 12 Smetna Street, 31-343, Krakow, Poland
| | - A Wnuk
- Department of Experimental Neuroendocrinology, Institute of Pharmacology, Polish Academy of Sciences, 12 Smetna Street, 31-343, Krakow, Poland
| | - W Lason
- Department of Experimental Neuroendocrinology, Institute of Pharmacology, Polish Academy of Sciences, 12 Smetna Street, 31-343, Krakow, Poland
| | - W Krzeptowski
- Department of Cell Biology and Imaging, Confocal Microscopy Laboratory, Institute of Zoology, Jagiellonian University, 9 Gronostajowa Street, 30-387, Krakow, Poland
| | - M Kajta
- Department of Experimental Neuroendocrinology, Institute of Pharmacology, Polish Academy of Sciences, 12 Smetna Street, 31-343, Krakow, Poland.
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Hoffmann C, Castro M, Rinken A, Leurs R, Hill SJ, Vischer HF. Ligand Residence Time at G-protein–Coupled Receptors—Why We Should Take Our Time To Study It. Mol Pharmacol 2015; 88:552-60. [DOI: 10.1124/mol.115.099671] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2015] [Accepted: 07/07/2015] [Indexed: 12/15/2022] Open
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Rzemieniec J, Litwa E, Wnuk A, Lason W, Gołas A, Krzeptowski W, Kajta M. Neuroprotective action of raloxifene against hypoxia-induced damage in mouse hippocampal cells depends on ERα but not ERβ or GPR30 signalling. J Steroid Biochem Mol Biol 2015; 146:26-37. [PMID: 24846829 DOI: 10.1016/j.jsbmb.2014.05.005] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/26/2014] [Revised: 05/07/2014] [Accepted: 05/11/2014] [Indexed: 01/03/2023]
Abstract
Raloxifene is the selective estrogen receptor modulator (SERM) currently used in clinical practice to activate estrogen receptors (ERs) in bone tissue and to antagonise ERs in breast and uterine cancers. Little is known, however, about mechanisms of action of raloxifene on hypoxia-induced neuronal cell damage. The aim of the present study was to investigate the neuroprotective potential of raloxifene against hypoxia-induced damage of mouse hippocampal cells in primary cultures, with a particular focus on raloxifene interactions with the classical nuclear ERs (ERα, ERβ) and the recently identified membrane ER G-protein-coupled receptor 30 (GPR30). In this study, 18 h of hypoxia increased hypoxia inducible factor 1 alpha (Hif1α) mRNA expression and induced apoptotic processes, such as loss of the mitochondrial membrane potential, activation of caspase-3 and fragmentation of cell nuclei based on Hoechst 33342 staining. These effects were accompanied by reduced ATPase and intracellular esterase activities as well as substantial lactate dehydrogenase (LDH) release from cells exposed to hypoxia. Our study demonstrated strong neuroprotective and anti-apoptotic caspase-3-independent actions of raloxifene in hippocampal cells exposed to hypoxia. Raloxifene also inhibited the hypoxia-induced decrease in Erα mRNA expression and attenuated the hypoxia-induced rise in Erβ and Gpr30 mRNA expression levels. Impact of raloxifene on hypoxia-affected Erα mRNA was mirrored by fluctuations in the protein level of the receptor as demonstrated by Western blot and immunofluorescent labelling. Raloxifene-induced changes in Erβ mRNA expression level were in parallel with ERβ immunofluorescent labeling. However, changes in Gpr30 mRNA level were not reflected by changes in the protein levels measured either by ELISA, Western blot or immunofluorescent staining at 24h post-treatment. Using specific siRNAs, we provided evidence for a key involvement of ERα, but not ERβ or GPR30 in neuroprotective action of raloxifene against hypoxia-induced cell damage. This study may have implications for the treatment or prevention of hypoxic brain injury and the administration of current or new generations of SERMs specific to ERα. This article is part of a Special Issue entitled "Sex steroids and brain disorders".
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Affiliation(s)
- J Rzemieniec
- Department of Experimental Neuroendocrinology, Institute of Pharmacology, Polish Academy of Sciences, 12 Smetna Street, 31-343 Krakow, Poland
| | - E Litwa
- Department of Experimental Neuroendocrinology, Institute of Pharmacology, Polish Academy of Sciences, 12 Smetna Street, 31-343 Krakow, Poland
| | - A Wnuk
- Department of Experimental Neuroendocrinology, Institute of Pharmacology, Polish Academy of Sciences, 12 Smetna Street, 31-343 Krakow, Poland
| | - W Lason
- Department of Experimental Neuroendocrinology, Institute of Pharmacology, Polish Academy of Sciences, 12 Smetna Street, 31-343 Krakow, Poland
| | - A Gołas
- Department of Genetics and Evolution, Institute of Zoology, Jagiellonian University, 9 Gronostajowa Street, 30-387 Krakow, Poland
| | - W Krzeptowski
- Department of Cell Biology and Imaging, Confocal Microscopy Laboratory, Institute of Zoology, Jagiellonian University, 9 Gronostajowa Street, 30-387 Krakow, Poland
| | - M Kajta
- Department of Experimental Neuroendocrinology, Institute of Pharmacology, Polish Academy of Sciences, 12 Smetna Street, 31-343 Krakow, Poland.
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Sunsandee N, Leepipatpiboon N, Ramakul P. Selective enantioseparation of levocetirizine via a hollow fiber supported liquid membrane and mass transfer prediction. KOREAN J CHEM ENG 2013. [DOI: 10.1007/s11814-013-0044-5] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Abstract
This article reviews the molecular biology of the interaction of histamine with its H1-receptor and describes the concept that H1-antihistamines are not receptor antagonists but are inverse agonists i.e. they produce the opposite effect on the receptor to histamine. It then discourages the use of first-generation H1-antihistamines in clinical practice today for two main reasons. First, they are less effective than second generation H1-antihistamines. Second, they have unwanted side effects, particularly central nervous system and anti-cholinergic effects, and have the potential for causing severe toxic reactions which are not shared by second-generation H1-antihistamines. There are many efficacious and safe second-generation H1-antihistamines on the market for the treatment of allergic disease. Of the three drugs highlighted in this review, levocetirizine and fexofenadine are the most efficacious in humans in vivo. However, levocetirizine may cause somnolence in susceptible individuals while fexofenadine has a relatively short duration of action requiring twice daily administration for full all round daily protection. While desloratadine is less efficacious, it has the advantages of rarely causing somnolence and having a long duration of action. Lastly, all H1-antihistamines have anti-inflammatory effects but it requires regular daily dosing rather than dosing 'on-demand' for this effect to be clinically demonstrable.
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Abstract
This article reviews the molecular biology of the interaction of histamine with
its H1-receptor and describes the concept that
H1-antihistamines are not receptor antagonists but are inverse
agonists i.e. they produce the opposite effect on the receptor to histamine. It
then discourages the use of first-generation H1-antihistamines in
clinical practice today for two main reasons. First, they are less effective
than second generation H1-antihistamines. Second, they have unwanted
side effects, particularly central nervous system and anti-cholinergic effects,
and have the potential for causing severe toxic reactions which are not shared
by second-generation H1-antihistamines. There are many efficacious
and safe second-generation H1-antihistamines on the market for the
treatment of allergic disease. Of the three drugs highlighted in this review,
levocetirizine and fexofenadine are the most efficacious in humans in
vivo. However, levocetirizine may cause somnolence in susceptible
individuals while fexofenadine has a relatively short duration of action
requiring twice daily administration for full all round daily protection. While
desloratadine is less efficacious, it has the advantages of rarely causing
somnolence and having a long duration of action. Lastly, all
H1-antihistamines have anti-inflammatory effects but it requires
regular daily dosing rather than dosing 'on-demand' for this effect to be
clinically demonstrable.
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Kusuhara H, Miura M, Yasui-Furukori N, Yoshida K, Akamine Y, Yokochi M, Fukizawa S, Ikejiri K, Kanamitsu K, Uno T, Sugiyama Y. Effect of Coadministration of Single and Multiple Doses of Rifampicin on the Pharmacokinetics of Fexofenadine Enantiomers in Healthy Subjects. Drug Metab Dispos 2012; 41:206-13. [DOI: 10.1124/dmd.112.048330] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
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26
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Slack RJ, Russell LJ, Hall DA, Luttmann MA, Ford AJ, Saunders KA, Hodgson ST, Connor HE, Browning C, Clark KL. Pharmacological characterization of GSK1004723, a novel, long-acting antagonist at histamine H(1) and H(3) receptors. Br J Pharmacol 2012; 164:1627-41. [PMID: 22022805 DOI: 10.1111/j.1476-5381.2011.01285.x] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
BACKGROUND AND PURPOSE Preclinical pharmacological characterization of GSK1004723, a novel, dual histamine H(1) and H(3) receptor antagonist. EXPERIMENTAL APPROACH GSK1004723 was characterized in vitro and in vivo using methods that included radioligand binding, intracellular calcium mobilization, cAMP production, GTPγS binding, superfused human bronchus and guinea pig whole body plethysmography. KEY RESULTS In cell membranes over-expressing human recombinant H(1) and H(3) receptors, GSK1004723 displayed high affinity, competitive binding (H(1) pKi = 10.2; H(3) pKi = 10.6). In addition, GSK1004723 demonstrated slow dissociation from both receptors with a t(1/2) of 1.2 and 1.5 h for H(1) and H(3) respectively. GSK1004723 specifically antagonized H(1) receptor mediated increases in intracellular calcium and H(3) receptor mediated increases in GTPγS binding. The antagonism exerted was retained after cell washing, consistent with slow dissociation from H(1) and H(3) receptors. Duration of action was further evaluated using superfused human bronchus preparations. GSK1004723 (100 nmol·L(-1) ) reversed an established contractile response to histamine. When GSK1004723 was removed from the perfusate, only 20% recovery of the histamine response was observed over 10 h. Moreover, 21 h post-exposure to GSK1004723 there remained almost complete antagonism of responses to histamine. In vivo pharmacology was studied in conscious guinea pigs in which nasal congestion induced by intranasal histamine was measured indirectly (plethysmography). GSK1004723 (0.1 and 1 mg·mL(-1) intranasal) antagonized the histamine-induced response with a duration of up to 72 h. CONCLUSIONS AND IMPLICATIONS GSK1004723 is a potent and selective histamine H(1) and H(3) receptor antagonist with a long duration of action and represents a potential novel therapy for allergic rhinitis.
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Affiliation(s)
- R J Slack
- Respiratory Biology, Respiratory CEDD, GlaxoSmithKline, Stevenage, UK
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Crowe A, Wright C. The impact of P-glycoprotein mediated efflux on absorption of 11 sedating and less-sedating antihistamines using Caco-2 monolayers. Xenobiotica 2011; 42:538-49. [PMID: 22188412 DOI: 10.3109/00498254.2011.643256] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Caco-2 cells were used to compare P-gp mediated efflux and passive permeability using bidirectional transport of 11 antihistamines. An efflux ratio >2 indicated active efflux, with PSC833 and GF120918 used as functional P-gp inhibitors. Antihistamines were measured directly by HPLC or LC/MS. Fexofenadine had an efflux ratio of 37, yet had negligible passive permeability, even in the presence of a pH gradient (0.1 × 10(-6) cm/sec). Its precursor, terfenadine, had an efflux ratio of 2.5, while cetirizine, desloratadine and hydroxyzine were 4, 7 and 14, respectively. After incubation with P-gp inhibitors, these ratios dropped significantly. Loratadine, by contrast, had equivalent transport in both directions and passive permeability was high (24 × 10(-6) cm/sec). Dimenhydrinate was the only other sedating antihistamine to exhibit efflux, with a ratio of 10. Gradient conditions of pH (6/7.4) increased efflux of terfenadine and desloratadine to over 31 and 38 fold respectively, yet this increased efflux was not associated with P-gp. Altering functional P-gp in the gut is likely to influence absorption of some sedating antihistamines such as dimenhydrinate and hydroxyzine and most less-sedating antihistamines except loratadine. In addition, desloratadine exhibits pH dependent efflux which could further induce variable absorption of this antihistamine.
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Affiliation(s)
- Andrew Crowe
- School of Pharmacy and Curtin Health Innovative Research Institute (CHIRI), Curtin University, Perth, Western Australia.
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Wittmann HJ, Seifert R, Strasser A. Influence of the N-terminus and the E2-loop onto the binding kinetics of the antagonist mepyramine and the partial agonist phenoprodifen to H1R. Biochem Pharmacol 2011; 82:1910-8. [DOI: 10.1016/j.bcp.2011.09.005] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2011] [Revised: 09/07/2011] [Accepted: 09/07/2011] [Indexed: 10/17/2022]
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In vitro characterisation of the duration of action of the histamine-1 receptor antagonist azelastine. Eur J Pharmacol 2011; 670:586-92. [PMID: 21946109 DOI: 10.1016/j.ejphar.2011.09.017] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2011] [Revised: 09/03/2011] [Accepted: 09/11/2011] [Indexed: 02/06/2023]
Abstract
Azelastine is a selective antagonist at the human histamine-1 receptor and is used clinically in the treatment of allergic rhinitis. In this study we have investigated its duration of action in vitro in an effort to characterise the receptor and tissue components involved. Chinese hamster ovary cell membrane fragments were used to determine the kinetics of azelastine at the H₁ receptor in a radioligand binding assay. Further duration of action studies were completed in tissue preparations using guinea-pig trachea and human bronchus. In radioligand binding studies, azelastine reached steady state at the H₁ receptor after approximately 41 min and exhibited a significantly slower dissociation rate constant from the receptor than the first generation antihistamine, diphenhydramine. In washout studies completed in guinea-pig and human airway in vitro tissue preparations, azelastine continued to antagonise the effects of histamine at the H₁ receptor for at least 18 h post-washout of the antagonist. This outcome was reversed following removal of the epithelium from guinea-pig isolated tracheal strips. These studies indicate there is a tissue component contributing to azelastine's duration of action, in addition to its direct H₁ receptor binding, with evidence suggesting a role for the epithelial layer.
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Pinyot A, Nikolovski Z, Bosch J, Segura J, Gutiérrez-Gallego R. On the use of cells or membranes for receptor binding: Growth hormone secretagogues. Anal Biochem 2010; 399:174-81. [DOI: 10.1016/j.ab.2010.01.003] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2009] [Revised: 12/17/2009] [Accepted: 01/06/2010] [Indexed: 11/16/2022]
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Watelet JB, Gillard M, Benedetti MS, Lelièvre B, Diquet B. Therapeutic management of allergic diseases. Drug Metab Rev 2009; 41:301-43. [PMID: 19601717 DOI: 10.1080/10837450902891204] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
Allergic diseases are characterized by the activation of inflammatory cells and by a massive release of mediators. The aim of this chapter was to describe succinctly the modes of action, indications, and side effects of the major antiallergic and antiasthmatic drugs. When considering the ideal pharmacokinetic characteristics of a drug, a poorly metabolized drug may confer a lower variability in plasma concentrations and metabolism-based drug interactions, although poorly metabolized drugs may be prone to transporter-based disposition and interactions. The ideal pharmacological properties of a drug include high binding affinity, high selectivity, and appropriate association and dissociation rates. Finally, from a patient perspective, the frequency and route of administration are important considerations for ease of use.
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Affiliation(s)
- Jean-Baptiste Watelet
- Department of Otohinolaryngology, Head and Neck Surgery, Ghent University Hospital, Ghent University, Belgium.
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Malany S, Hernandez LM, Smith WF, Crowe PD, Hoare SRJ. Analytical method for simultaneously measuring ex vivo drug receptor occupancy and dissociation rate: application to (R)-dimethindene occupancy of central histamine H1 receptors. J Recept Signal Transduct Res 2009; 29:84-93. [PMID: 19308787 DOI: 10.1080/10799890902721339] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
We introduce a novel experimental method to determine both the extent of ex vivo receptor occupancy of administered compound and its dissociation rate constant (k4). [Here, we reference k4 as the rate of offset of unlabeled ligand in convention with Motulsky and Mahan (1)]. We derived a kinetic rate equation based on the dissociation rate constant for an unlabeled compound competing for the same site as a labeled compound and describe a model to simulate fractional occupancy. To validate our model, we performed in vitro kinetics and ex vivo occupancy experiments in rat cortex with varying concentrations of (R)-dimethindene, a sedating antihistamine. Brain tissue was removed at various times post oral administration, and histamine H1 receptor ligand [3H]-doxepin binding to homogenates from drug-treated or vehicle-treated rats was measured at multiple time points at room temperature. Fractional occupancy and k4 for (R)-dimethindene binding to H1 receptors were calculated by using our proposed model. Rats dosed with 30 and 60 mg/kg (R)-dimethindene showed 42% and 67% occupancy of central H1 receptors, respectively. These results were comparable to occupancy data determined by equilibrium radioligand binding. In addition, drug k4 rate determined by using our ex vivo method was equivalent to k4 determined by in vitro competition kinetics (dissociation half-life t(1/2) approximately 30 min). The outlined method can be used to assess, by simulation and experiment, occupancy for compounds based on dissociation rate constants and contributes to current efforts in drug optimization to profile antagonist efficacy in terms of its kinetic drug-target binding parameters. Data described by the method may be analyzed with commercially available software. Suggested fitting procedures are given in the appendix.
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Affiliation(s)
- Siobhan Malany
- Division of Emerging New Technologies, Neurocrine Biosciences, San Diego, California, USA.
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Church MK, Gillard M, Sargentini-Maier ML, Poggesi I, Campbell A, Benedetti MS. From pharmacokinetics to therapeutics. Drug Metab Rev 2009; 41:455-74. [PMID: 19601722 DOI: 10.1080/10837450902891535] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
Whilst pharmacokinetics describe the relationship between dose levels and concentration-time profiles of a drug in the body and pharmacodynamics describe the concentration-response relationships, pharmacokinectics-pharmacodynamics(PK-PD) models link these two items providing a framework for modelling the time course of drug response. In this chapter, PK-PD models, describing the therapeutic effects of drugs used for the therapy of allergic diseases have been reviewed. Emphasis was given also to the description of the receptor occupancy, which is tightly related to the downstream clinical response. PK - PD models describing unwanted effects were also commented. An integrated use of these models allows choosing appropriate dosing regimens and providing an objective evaluation of the benefit/risk balance.
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Affiliation(s)
- Martin K Church
- Charité - Universitätsmedizini Berlin, Germany. mkc@ southampton.ac.uk
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Nettis E, Calogiuri GF, Di Leo E, Cardinale F, Macchia L, Ferrannini A, Vacca A. Once daily levocetirizine for the treatment of allergic rhinitis and chronic idiopathic urticaria. J Asthma Allergy 2008; 2:17-23. [PMID: 21437140 PMCID: PMC3048603 DOI: 10.2147/jaa.s3022] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Levocetirizine is the pharmacologically active enantiomer of cetirizine. It is a potent histamine H-1 receptor antagonist with anti-inflammatory and antiallergic properties. The review analyses the levocetirizine's properties in terms of safety and efficacy both in allergic rhinitis and urticarioid syndromes.
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Affiliation(s)
- E Nettis
- Section of Allergology and Clinical Immunology, Department of Internal Medicine and Infectious Diseases
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Devillier P, Roche N, Faisy C. Clinical Pharmacokinetics and Pharmacodynamics of Desloratadine, Fexofenadine and Levocetirizine. Clin Pharmacokinet 2008; 47:217-30. [PMID: 18336052 DOI: 10.2165/00003088-200847040-00001] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Affiliation(s)
- Philippe Devillier
- Laboratory of Pharmacology, UPRES EA 220, Université de Versailles Saint-Quentin, Hôpital Foch, Suresnes, France.
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Ständer S, Weisshaar E, Luger TA. Neurophysiological and neurochemical basis of modern pruritus treatment. Exp Dermatol 2007; 17:161-9. [PMID: 18070080 DOI: 10.1111/j.1600-0625.2007.00664.x] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Chronic pruritus of any origin is a frequent discomfort in daily medical practice, and its therapy is challenging. Frequently, the underlying origin may not be identified and symptomatic therapy is necessary. Conventional treatment modalities such as antihistamines often lack efficacy, and hence new therapeutic strategies are necessary. The neuronal mechanisms underlying chronic pruritus have been partly identified during the past years and offer new therapeutic strategies. For example, mast cell degranulation, activation of neuroreceptors on sensory nerve fibres and neurogenic inflammation have been identified to be involved in induction and chronification of the symptom. Accordingly, controlling neuroreceptors such as cannabinoid receptors by agonists or antagonists showed high antipruritic efficacy. Pruritus is transmitted to the central nervous system by specialized nerve fibres and sensory receptors. It has been demonstrated that pruritus and pain have their own neuronal pathways with broad interactions. Accordingly, classical analgesics for neuropathic pain (gabapentin, antidepressants) also exhibit antipruritic efficacy upon clinical use. In summary, these recent developments show that highlighting the basis of pruritus offers modern neurophysiological and neurochemical therapeutic models and the possibility to treat patients with refractory itching of different origin.
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Affiliation(s)
- Sonja Ständer
- Clinical Neurodermatology, Department of Dermatology, University of Muenster, Muenster, Germany.
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Hair PI, Scott LJ. Levocetirizine: a review of its use in the management of allergic rhinitis and skin allergies. Drugs 2006; 66:973-96. [PMID: 16740020 DOI: 10.2165/00003495-200666070-00017] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Levocetirizine (Xyzal) is a selective, potent, oral histamine H(1) receptor antagonist of the latest generation that is licensed for the symptomatic treatment of allergic rhinitis (including persistent allergic rhinitis [PER]) and chronic idiopathic urticaria (CIU). Large, well designed trials indicate that levocetirizine is effective and generally well tolerated in the treatment of allergic rhinitis and CIU. Its pharmacological profile offers many positive aspects: a rapid onset and long duration of antihistaminic effect; rapid absorption and high bioavailability; a low potential for drug interactions; a low volume of distribution; and a lack of effect on cognition, psychomotor function and the cardiovascular system. Allergen challenge chamber studies suggest that levocetirizine has better efficacy than desloratadine, loratadine or fexofenadine. Well controlled, long-term studies with other later-generation H(1) receptor antagonists are required to fully define its clinical profile relative to other agents in this class. Overall, levocetirizine is a valuable addition to the oral H(1) receptor antagonists available for the treatment of allergic rhinitis and as first-line therapy in patients with CIU.
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Affiliation(s)
- Philip I Hair
- Adis International Limited, 51 Centorian Drive, Mairangi Bay, Auckland 1311, New Zealand.
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Forsten-Williams K, Cassino TR, Delo LJ, Bellis AD, Robinson AS, Ryan TE. Enhanced insulin-like growth factor-I (IGF-I) cell association at reduced pH is dependent on IGF binding protein-3 (IGFBP-3) interaction. J Cell Physiol 2006; 210:298-308. [PMID: 17044083 DOI: 10.1002/jcp.20849] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
The cellular microenvironment impacts how signals are transduced by cells and plays a key role in tissue homeostasis. Although pH is generally well regulated, there are a number of situations where acidosis occurs and our work addresses how low pH impacts cell association of insulin-like growth factor-I (IGF-I) in the presence of IGF binding protein-3 (IGFBP-3). We have previously shown that IGF-I cell binding was enhanced in the presence of IGFBP-3 at low pH and now show that this binding is IGFBP-mediated as it is inhibited by Y60L-IGF-I, a mutant with reduced affinity for the IGF receptor (IGF-IR), and unaffected by insulin, which binds but not IGFBPs. Using surface plasmon resonance (SPR), we show that direct binding between IGF-I and IGFBP-3 is pH sensitive. Despite this, the key step in the process appears to be IGFBP-3 cell surface association as Long-R(3)-IGF-I, a mutant with reduced affinity for IGFBPs, shows a similar increase in cell association at pH 5.8 in the presence of IGFBP-3 but does not exhibit pH-dependent binding by SPR. Further, analysis indicates a large increase in low-affinity binding sites for IGF-I in the presence of IGFBP-3 and an elimination of IGF-I enhanced binding when a non-cell associating mutant of IGFBP-3 is added in place of IGFBP-3. That the IGFBP-3-mediated binding localizes IGF-I away from IGF-IR is suggested by triton-solubility testing and indicates additional complexities to IGF-I regulation by IGFBP-3. Identifying the pH-dependent binding partner(s) for IGFBP-3 is a necessary next step in deciphering this process.
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Affiliation(s)
- Kimberly Forsten-Williams
- Department of Chemical Engineering, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061, USA.
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