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Grable S, Houchard G, Rossfeld Z. Alpha Alert: Utilization of Transdermal Clonidine for Refractory Agitation. J Pain Palliat Care Pharmacother 2024; 38:149-152. [PMID: 38484176 DOI: 10.1080/15360288.2024.2327868] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2023] [Accepted: 03/01/2024] [Indexed: 06/06/2024]
Abstract
Alpha-2 agonists are under-recognized for their class effects yet offer potential benefit in specialty palliative care via decreasing sympathetic output, inducing sedation, and modulating pain. Especially in clinical contexts where agitation predominates and patients are intolerant of oral medication route, transdermal medication delivery is advantageous. We report a case of agitated behaviors in setting of mixed Alzheimer/vascular-type dementia limiting hospital discharge to nursing facility that were ameliorated with transdermal clonidine. We suggest palliative clinicians routinely conceptualize the seemingly disparate alpha-2 agonists as a class for effective symptom palliation especially as new clinical evidence becomes available.
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Affiliation(s)
| | - Gary Houchard
- MD, MA are with the Division of Palliative Medicine, The Ohio State University Wexner Medical Center, Columbus, Ohio, USA
| | - Zach Rossfeld
- PharmD is with the Palliative Medicine, OhioHealth, Columbus, Ohio, USA
- MD, MA are with the Division of Palliative Medicine, The Ohio State University Wexner Medical Center, Columbus, Ohio, USA
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Wang Y, Nguyen DT, Anesi J, Alramahi A, Witting PK, Chai Z, Khan AW, Kelly J, Denton KM, Golledge J. Moxonidine Increases Uptake of Oxidised Low-Density Lipoprotein in Cultured Vascular Smooth Muscle Cells and Inhibits Atherosclerosis in Apolipoprotein E-Deficient Mice. Int J Mol Sci 2023; 24:ijms24043857. [PMID: 36835270 PMCID: PMC9960795 DOI: 10.3390/ijms24043857] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2022] [Revised: 02/07/2023] [Accepted: 02/13/2023] [Indexed: 02/17/2023] Open
Abstract
This study aimed to investigate the effect of the sympatholytic drug moxonidine on atherosclerosis. The effects of moxonidine on oxidised low-density lipoprotein (LDL) uptake, inflammatory gene expression and cellular migration were investigated in vitro in cultured vascular smooth muscle cells (VSMCs). The effect of moxonidine on atherosclerosis was measured by examining aortic arch Sudan IV staining and quantifying the intima-to-media ratio of the left common carotid artery in apolipoprotein E-deficient (ApoE-/-) mice infused with angiotensin II. The levels of circulating lipid hydroperoxides in mouse plasma were measured by ferrous oxidation-xylenol orange assay. Moxonidine administration increased oxidised LDL uptake by VSMCs via activation of α2 adrenoceptors. Moxonidine increased the expression of LDL receptors and the lipid efflux transporter ABCG1. Moxonidine inhibited mRNA expression of inflammatory genes and increased VSMC migration. Moxonidine administration to ApoE-/- mice (18 mg/kg/day) decreased atherosclerosis formation in the aortic arch and left common carotid artery, associated with increased plasma lipid hydroperoxide levels. In conclusion, moxonidine inhibited atherosclerosis in ApoE-/- mice, which was accompanied by an increase in oxidised LDL uptake by VSMCs, VSMC migration, ABCG1 expression in VSMCs and lipid hydroperoxide levels in the plasma.
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Affiliation(s)
- Yutang Wang
- Discipline of Life Science, Institute of Innovation, Science and Sustainability, Federation University Australia, Ballarat, VIC 3350, Australia
- Correspondence:
| | - Dinh Tam Nguyen
- Discipline of Life Science, Institute of Innovation, Science and Sustainability, Federation University Australia, Ballarat, VIC 3350, Australia
| | - Jack Anesi
- Discipline of Life Science, Institute of Innovation, Science and Sustainability, Federation University Australia, Ballarat, VIC 3350, Australia
| | - Ahmed Alramahi
- Discipline of Life Science, Institute of Innovation, Science and Sustainability, Federation University Australia, Ballarat, VIC 3350, Australia
| | - Paul K. Witting
- Molecular Biomedicine Theme, School of Medical Sciences, Faculty of Medicine and Health, Charles Perkins Centre, The University of Sydney, Sydney, NSW 2006, Australia
| | - Zhonglin Chai
- Department of Diabetes, Central Clinical School, Monash University, Melbourne, VIC 3004, Australia
| | - Abdul Waheed Khan
- Department of Diabetes, Central Clinical School, Monash University, Melbourne, VIC 3004, Australia
| | - Jason Kelly
- Fiona Elsey Cancer Research Institute, Ballarat, VIC 3350, Australia
| | - Kate M. Denton
- Department of Physiology, Monash University, Melbourne, VIC 3800, Australia
- Cardiovascular Disease Program, Monash Biomedicine Discovery Institute, Monash University, Melbourne, VIC 3800, Australia
| | - Jonathan Golledge
- Queensland Research Centre for Peripheral Vascular Disease, College of Medicine and Dentistry, James Cook University, Townsville, QLD 4811, Australia
- Department of Vascular and Endovascular Surgery, The Townsville University Hospital, Townsville, QLD 4814, Australia
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Ojeda ML, Sobrino P, Rua RM, Gallego-Lopez MDC, Nogales F, Carreras O. Selenium, a dietary-antioxidant with cardioprotective effects, prevents the impairments in heart rate and systolic blood pressure in adolescent rats exposed to binge drinking treatment. THE AMERICAN JOURNAL OF DRUG AND ALCOHOL ABUSE 2021; 47:680-693. [PMID: 34582310 DOI: 10.1080/00952990.2021.1973485] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
BACKGROUND Binge drinking (BD) during adolescence is related to cardiovascular alterations. Selenium (Se) is an essential trace element with antioxidant, anti-inflammatory and antiapoptotic properties, essential for correct heart function. OBJECTIVES To study the protective cardiovascular effects of selenium in adolescent rats exposed to a BD-like procedure. METHODS 32 adolescent male rats exposed to an intraperitoneally BD-like model or not, and supplemented with 0.4ppm of selenite or not, were divided into 4 groups: control, alcohol, control-selenium and alcohol-selenium. Blood pressure and heart rate (HR) were determined after experimentation. Se deposits, oxidative balance and the expression of glutathione peroxidases (GPxs), NF-kB and caspase-3 were measured in the heart. Also, DNA instability in rat lymphocytes and serum vascular markers were determined. Statistical analysis was performed with the ANOVA model. RESULTS The BD-like model depleted Se heart deposits (p < .01), decreased GPx activity (p < .01) and GPx1 (p < .001) and GPx4 (p < .05) expression, increased NF-kB (p < .01), caspase-3 (p < .001) expression, and generated oxidation in myocytes. Outside the heart, the BD-like model caused double-strand breaks in lymphocyte DNA and increased all the vascular markers measured. These cardiovascular alterations were related to higher systolic (p < .001) and diastolic (p < .05) blood pressure and HR (p < .05). In the heart, Se supplementation in BD-exposed rats significantly increased Se deposits (p < .001) and improved oxidative balance and vascular damage, including increased GPxs and decreased NF-kB and caspase-3 activation, consequently decreasing systolic (p < .05) blood pressure and HR (p < .01). CONCLUSIONS Se supplementation presents cardioprotective effects since it reversed HR and systolic blood pressure observed in BD-exposed adolescent rats.
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Affiliation(s)
- M Luisa Ojeda
- Department of Physiology, Faculty of Pharmacy, Seville University, Seville, Spain
| | - Paula Sobrino
- Department of Physiology, Faculty of Pharmacy, Seville University, Seville, Spain
| | - Rui Manuel Rua
- Faculty of Health Sciences, University Fernando Pessoa, Porto, Portugal
| | | | - Fátima Nogales
- Department of Physiology, Faculty of Pharmacy, Seville University, Seville, Spain
| | - Olimpia Carreras
- Department of Physiology, Faculty of Pharmacy, Seville University, Seville, Spain
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Safaryan AS, Nebieridze DV. Sympathetic hyperactivity in patients with hypertension: pathogenesis and treatment. Part II. КАРДИОВАСКУЛЯРНАЯ ТЕРАПИЯ И ПРОФИЛАКТИКА 2021. [DOI: 10.15829/1728-8800-2021-2845] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022] Open
Abstract
The second part of the review considers different classes of drugs affecting blood pressure in increased activity of the sympathetic nervous system. Additional possibilities are discussed on how to reduce the negative effect of sympathetic hyperactivity on cardiovascular system and improve the prognosis.
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Affiliation(s)
- A. S. Safaryan
- National Medical Research Center for Therapy and Preventive Medicine
| | - D. V. Nebieridze
- National Medical Research Center for Therapy and Preventive Medicine
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Taguchi K, Bessho N, Hasegawa M, Narimatsu H, Matsumoto T, Kobayashi T. Co-treatment with clonidine and a GRK2 inhibitor prevented rebound hypertension and endothelial dysfunction after withdrawal in diabetes. Hypertens Res 2018; 41:263-274. [DOI: 10.1038/s41440-018-0016-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2017] [Revised: 09/28/2017] [Accepted: 11/17/2017] [Indexed: 12/25/2022]
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van Zwieten PA. Antihypertensive drugs interacting with central imidazoline (I1)-receptors. Expert Opin Investig Drugs 2005; 7:1781-93. [PMID: 15991929 DOI: 10.1517/13543784.7.11.1781] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Central imidazoline (I(1))-receptors have been recognised as targets of a new class of centrally acting antihypertensives. The stimulation of these I(1)-receptors induces peripheral sympatho-inhibition and a reduction of (elevated) blood pressure. Moxonidine and rilmenidine are the prototypes of this new class of centrally acting antihypertensives. These imidazoline receptor stimulants are effective antihypertensives with a haemodynamic profile which is attractive from a pathophysiological point of view. Since both moxonidine and rilmenidine have a much weaker affinity for central (2)-adrenoceptors than classic centrally acting drugs, for example, clonidine and alpha-methyl-DOPA, the side-effects profile of the I(1)-receptor stimulants is significantly better. The imidazoline (I(1))-receptor stimulants are the subject of the current survey. They appear to offer the possibility of developing centrally acting antihypertensives with the same attractive haemodynamic characteristics as the classic alpha(2)-adrenoceptor stimulants, but with clearly better tolerability. Their potential use in the treatment of congestive heart failure and the metabolic syndrome is subject to clinical investigation.
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Affiliation(s)
- P A van Zwieten
- Department of Pharmacotherapy, Academic Medical Centre, University of Amsterdam, Meibergdreef 15, 1105 AZ Amsterdam, The Netherlands
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Abstract
Recent years have seen a considerable media interest in the adverse effects of the selective serotonin reuptake inhibitors (SSRIs). This has led to claims that these antidepressants may lead to suicide and homicide and that they cause dependence or even addiction. Such claims have caused great concerns to many patients and have confused doctors in both primary care and psychiatric practice. In this article I review the basis of these claims and show that many seem to emerge from the misinterpretation of evidence and the use of imprecise definitions. Although the SSRIs are not free of problems they compare very favourably with other antidepressants and other classes of psychotropic drugs. There is no evidence they are addictive in the formal sense of leading to a drug dependence syndrome. Some suggestions on the way these issues can be more precisely defined and studied in future are given.
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Affiliation(s)
- David J Nutt
- University of Bristol, Psychopharmacology Unit, School of Medical Sciences, University Walk, Bristol, UK.
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Kroin JS, McCarthy RJ, Penn RD, Lubenow TJ, Ivankovich AD. Continuous intrathecal clonidine and tizanidine in conscious dogs: analgesic and hemodynamic effects. Anesth Analg 2003; 96:776-782. [PMID: 12598262 DOI: 10.1213/01.ane.0000048087.57487.0c] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
UNLABELLED Alpha-2-adrenergic agonists, such as clonidine, produce antinociception in animal pain models after intrathecal administration. However, clinical usage is limited by cardiovascular side effects. To investigate alternative alpha(2)-adrenergic agonists as analgesics, we implanted six dogs with an intrathecal catheter and infusion pump. After baseline saline infusion, animals received clonidine or tizanidine (crossover study) each week at escalating doses of 125-750 microg/h. Analgesia, blood pressure, heart rate, respiratory rate, sedation, and coordination were evaluated. A 28-day safety study was performed with another nine dogs receiving intrathecal tizanidine (3 or 6 mg/d) or saline. Equal doses of clonidine and tizanidine produce the same antinociception in thermal withdrawal tests. Blood pressure was reduced with 125-500 microg/h of clonidine, but not with tizanidine at any dose. Clonidine 250 microg/h reduced heart rate by 45.8%, and five of six animals had bradyarrhythmias (marked bradycardia), whereas tizanidine decreased heart rate by 15.1% without arrhythmias, even at the largest dose. Respiratory rate decreased with 250 microg/h of clonidine and larger doses. Sedation or incoordination occurred only at the largest dose for either drug. The safety study indicated that 3 mg/d of tizanidine in dogs produced no side effects or histopathologic changes. Tizanidine may be a useful alternative in patients experiencing cardiovascular side effects with intrathecal infusion of clonidine. IMPLICATIONS Clonidine is an effective spinal analgesic, but it is dose-limited by cardiovascular side effects. We compared the analgesic properties and side effects of clonidine with those of a similar drug, tizanidine. Continuous spinal infusion of tizanidine produced similar analgesia as clonidine, but with fewer adverse effects on blood pressure and heart rate.
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Affiliation(s)
- Jeffrey S Kroin
- Departments of *Anesthesiology and †Neurosurgery, Rush Medical College, Chicago, Illinois
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11
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Parkin ML, Godwin SJ, Head GA. Importance of imidazoline-preferring receptors in the cardiovascular actions of chronically administered moxonidine, rilmenidine and clonidine in conscious rabbits. J Hypertens 2003; 21:167-78. [PMID: 12544449 DOI: 10.1097/00004872-200301000-00027] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
OBJECTIVE To determine the involvement of central imidazoline receptors in the cardiovascular actions of the chronically administered antihypertensive agents moxonidine, rilmenidine and clonidine. DESIGN AND METHODS In 21 rabbits with implanted fourth-ventricular catheters, we investigated the central effects of three cumulative doses of an I(1)-imidazoline/alpha(2)-adrenoceptor antagonist, efaroxan, and of an alpha(2)-adrenoceptor antagonist, 2-methoxyidazoxan (2-MI), on the changes in blood pressure and heart rate (HR) elicited by chronic subcutaneous administration of moxonidine, rilmenidine and clonidine, after 1 and 3 weeks of treatment. A low, medium and high dose of 2-MI was matched to three doses of efaroxan, such that each produced equal reversal of the hypotension induced by fourth-ventricular alpha-methyldopa and hence produced a similar degree of alpha(2)-adrenoceptor blockade. RESULTS Clonidine and moxonidine, at doses of 1 mg/kg per day, and rilmenidine at 5 mg/kg per day, produced sustained reductions in mean arterial pressure of 13 +/- 3, 15 +/- 2 and 13 +/- 2 mmHg, respectively over the 3-week treatment period, but did not alter HR. Central administration of efaroxan on day 9 and day 23 of treatment produced a greater increase in blood pressure than did 2-MI with all three antihypertensive agents. Blood pressure reached levels that were significantly above the original control values. By contrast, the alpha(2)-adrenoceptor antagonist 2-MI only induced a rebound blood pressure effect in clonidine- and to a lesser extent in rilmenidine-treated rabbits. Both efaroxan and 2-MI produced a similar degree of tachycardia in moxonidine-, rilmenidine- and clonidine-treated animals.(2) CONCLUSIONS The greater effect of efaroxan compared to the alpha(2)-adrenoceptor antagonist 2-MI suggests that the hypotension induced by chronic subcutaneous administration of moxonidine, rilmenidine and clonidine is mediated predominantly via an action on central imidazoline receptors. Furthermore, all agents showed a propensity to produce rebound hypertension with imidazoline receptor blockade. However, only clonidine showed a rebound phenomenon when challenged by acute central alpha(2)-adrenoceptor blockade
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Affiliation(s)
- Monique L Parkin
- Neuropharmacology Laboratory, Baker Heart Research Institute, Commercial Road Prahran, St Kilda Road Central, Melbourne, Victoria 8008, Australia
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Robles Pérez-Monteoliva N. Tratamiento de la hipertensión arterial con agentes centrales. HIPERTENSION Y RIESGO VASCULAR 2003. [DOI: 10.1016/s1889-1837(03)71339-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Wenzel RR, Bruck H, Noll G, Schäfers RF, Daul AE, Philipp T. Antihypertensive drugs and the sympathetic nervous system. J Cardiovasc Pharmacol 2001; 35:S43-52. [PMID: 11346218 DOI: 10.1097/00005344-200000004-00006] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
The sympathetic nervous system (SNS) plays an important role in the regulation of blood pressure homeostasis and cardiac function. Furthermore, the increased SNS activity is a predictor of mortality in patients with hypertension, coronary artery disease and congestive heart failure. Experimental data and a few clinical trials suggest that there are important interactions between the main pressor systems, i.e. the SNS, the renin-angiotensin system and the vascular endothelium with the strongest vasoconstrictor, endothelin. The main methods for the assessment of SNS activity are described. Cardiovascular drugs of different classes interfere differently with the SNS and the other pressor systems. Pure vasodilators including nitrates, alpha-blockers and dihydropyridine (DHP)-calcium channel blockers increase SNS activity. Finally, central sympatholytics and possibly phenylalkylamine-type calcium channel blockers reduce SNS activity. The effects of angiotensin-II receptor antagonists on SNS activity in humans is not clear; experimental data are discussed in this review. There are important interactions between the pressor systems under experimental conditions. Recent studies in humans suggest that an activation of the SNS with pure vasodilators in parallel increases plasma endothelin. It can be assumed that, in cardiovascular diseases with already enhanced SNS activity, drugs which do not increase SNS activity or even lower it are preferable. Whether this reflects in lower mortality needs to be investigated in intervention trials.
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Affiliation(s)
- R R Wenzel
- Department of Internal Medicine, University Hospital, Essen, Germany
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Abstract
The I1-imidazoline receptor is a novel neurotransmitter receptor found mainly in the brainstem, adrenal medulla and kidney. The actions of moxonidine are described at the level of individual biomolecules, cells, tissues, organs and finally with integrative functions. The receptor functions at the cellular level works through arachidonic acid and phospholipid signaling cascades in neuronal cells with the net result of inhibiting sympathetic premotor neurons.
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Affiliation(s)
- P Ernsberger
- Department of Nutrition, Case Western University, School of Medicine Cleveland, Ohio 44106, USA
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15
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van Zwieten PA. Centrally acting imidazoline I1-receptor agonists: do they have a place in the management of hypertension? Am J Cardiovasc Drugs 2001; 1:321-6. [PMID: 14728014 DOI: 10.2165/00129784-200101050-00002] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Centrally acting imidazoline I(1)-receptor agonists such as moxonidine and rilmenidine induce peripheral sympathoinhibition via the stimulation of hypothetical I(1)-receptors in the rostral ventrolateral medulla. Because of a rather weak affinity for alpha(2)-adrenoceptors, the use of these agents is associated with a lower incidence of adverse reactions, such as sedation and dry mouth, compared with classic centrally acting alpha(2)-adrenoceptor agonists (clonidine, guanfacine, methyldopa). The antihypertensive efficacy of moxonidine and rilmenidine is well documented, and they display a favorable hemodynamic profile. Their tolerability is better than that of the aforementioned centrally acting antihypertensive agents. However, long-term outcome data for moxonidine and rilmenidine are not available, and neither is a quantitative evaluation of their adverse effects. There exists some uncertainty with respect to the identity of the imidazoline I(1)-receptor, which has so far not been cloned. Furthermore, it would be desirable to develop highly selective I(1)-receptor agonists as successor drugs to moxonidine and rilmenidine. Although available data indicate that I(1)-receptor agonists are effective in patients with hypertension, comparative data versus agents such as beta-blockers, diuretics, calcium channel antagonists and ACE inhibitors are required to establish their position in the treatment of hypertension. Finally, I(1)-receptor agonists have potential in the treatment of patients with CHF and those with the metabolic syndrome; syndrome X.
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Affiliation(s)
- P A van Zwieten
- Department of Pharmacotherapy, Cardiology and Cardiothoracic Surgery, Academic Medical Centre, University of Amsterdam, Amsterdam, The Netherlands
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16
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Lusthof KJ, Lameijer W, Zweipfenning PG. Use of clonidine for chemical submission. JOURNAL OF TOXICOLOGY. CLINICAL TOXICOLOGY 2000; 38:329-32. [PMID: 10866335 DOI: 10.1081/clt-100100940] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
CASE REPORT An East-European prostitute in Amsterdam robbed several victims, after having sedated them with clonidine solution (available as plastic ampoules of eyedrops) added to her victims' drinks. One victim was hospitalized. His symptoms included bradycardia, hypotension, hypothermia, pallor, cyanosis, and impaired consciousness. Treatment included isoprenaline for 28 hours. The victim was released from hospital the next day. In court, the female offender confessed and was sentenced to prison for 3 1/2 years. She may have administered doses as high as 8 mg clonidine.
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Affiliation(s)
- K J Lusthof
- Department of Toxicology, Forensic Sciences Institute, Rijswijk, The Netherlands.
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McKnight KA, Rupp H, Dhalla KS, Beamish RE, Dhalla NS. Biphasic changes in heart performance with food restriction in rats. J Appl Physiol (1985) 1999; 87:1909-13. [PMID: 10562636 DOI: 10.1152/jappl.1999.87.5.1909] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
To examine effects of food restriction resembling very-low-calorie dieting on heart performance, normal rats were fed 25% of ad libitum food intake for 14 days. Although heart weight decreased (P < 0.05) after 5 days, left ventricular systolic pressure as well as rates of pressure development and fall were increased (P < 0.05) at 7 days and decreased (P < 0.05) after 14 days. Systolic and diastolic blood pressures were also increased from 5 to 7 days and decreased after 14 days. The increased hemodynamic performance of heart was associated with a raised plasma norepinephrine concentration, which peaked at day 7 of food restriction; epinephrine concentration was increased (P < 0.05) also at day 7. An increased catecholamine synthesis was indicated by the raised (P < 0.05) plasma dopamine beta-hydroxylase activity at 3 days, but this was decreased (P < 0. 05) at 14 days. The concentration of dopamine in the heart was increased (P < 0.05) at 2-14 days, of norepinephrine at 7-14 days, and of epinephrine at 10 and 14 days. Food restriction thus appears initially to be associated with an enhanced catecholamine influence on the heart and is followed by a depressed cardiac performance.
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Affiliation(s)
- K A McKnight
- Institute of Cardiovascular Sciences, St. Boniface General Hospital Research Centre, and Department of Physiology, Faculty of Medicine, University of Manitoba, Winnipeg, Canada
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Abstract
The classic centrally acting antihypertensives such as clonidine, guanfacine and alpha-methyl-DOPA (via its active metabolite alpha-methyl-noradrenaline) induce peripheral sympathoinhibition and a fall in blood pressure as a result of alpha2-adrenoceptor stimulation in the brain stem. These drugs have lost much of their clinical importance because of their unfavourable side-effects (sedation, dry mouth, impotence), which are also mediated by alpha2-adrenoceptors, although in other anatomical regions. Moxonidine and rilmenidine are the examples of a new class of centrally acting antihypertensives, which cause peripheral sympathoinhibition mediated by imidazoline (I1)-receptors in the rostral ventromedulla (RVLM). Their side-effect profile appears to be better than that of clonidine and alpha-methyl-DOPA, probably because of a weaker affinity for alpha2-adrenoceptors. The mode of action, haemodynamic profile, antihypertensive efficacy and adverse reactions of the classic and newer centrally acting antihypertensives are the subject of the present survey. Attention is also paid to other therapeutic applications of centrally acting antihypertensives, such as congestive heart failure and the metabolic syndrome.
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Affiliation(s)
- P A van Zwieten
- Department of Pharmacotherapy, Academic Medical Centre, University of Amsterdam, The Netherlands
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Abstract
In addition to genetic factors, lifestyle has a predominant influence on primary hypertension and noninsulin-dependent diabetic mellitus (NIDDM). We initiated studies using radiotelemetry for characterizing molecular events linked with excess calorie intake and psychologic stress. An increased calorie intake was associated with raised (p < 0.05) systolic and diastolic blood pressure as well as heart rate independent of day-night cycle. Sympathetic activity was in excess when related to the unchanged motility. The hyperkinetic hypertension is expected to result in adverse remodeling of resistance vessels and to aggravate insulin resistance. To examine adverse effects of psychological stress, rats were subjected to intermittent food pellet feeding. Urinary catecholamines and cardiac norepinephrine stores were increased (p < 0.05). The depressed (p < 0.05) rate of Ca2+ uptake of sarcoplasmic reticulum is expected to contribute to cellular Ca2+ overload. These lifestyle influences strengthen the notion of an excess catecholamine syndrome which requires selective reduction of sympathetic outflow of the brain by I1-receptor agonists.
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Affiliation(s)
- H Rupp
- Molecular Cardiology Laboratory, Philipps University of Marburg, Germany
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20
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Van Zwieten PA, Peters SL. Central I1-imidazoline receptors as targets of centrally acting antihypertensive drugs. Clinical pharmacology of moxonidine and rilmenidine. Ann N Y Acad Sci 1999; 881:420-9. [PMID: 10415946 DOI: 10.1111/j.1749-6632.1999.tb09390.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Moxonidine and rilmenidine are moderately selective I1-receptor stimulants. The imidazoline (I1) agonists cause peripheral sympathoinhibition, triggered at the level of central nervous imidazoline receptors. Imidazoline receptor stimulants are effective antihypertensive agents with a hemodynamic profile that is attractive from a pathophysiologic point of view. The antihypertensive activity of these agents is caused by vasodilatation and reduced peripheral vascular resistance. Left ventricular end-diastolic and end-systolic volume is reduced, whereas heart rate, stroke volume, cardiac output, and pulmonary artery pressures are largely unchanged. Long-term left ventricular hypertrophy is reduced. Both drugs, when applied in a once-daily dosage schedule, appear to control hypertension in most patients. Both drugs have been compared with representative agents from the major classes of antihypertensive drugs in controlled trials and found to be equally effective in blood pressure control. The incidence and severity of side effects are lower than those for clonidine, particularly with respect to sedation. A rebound (withdrawal) phenomenon has so far not been reported for moxonidine and rilmenidine. Therefore, I1-receptor stimulants offer the possibility of developing centrally acting agents with a better side-effect profile than do the classic alpha 2-adrenoceptor stimulants.
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Affiliation(s)
- P A Van Zwieten
- Department of Pharmacotherapy, University of Amsterdam, The Netherlands
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21
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New or developing antihypertensive agents. Curr Opin Cardiol 1997. [DOI: 10.1097/00001573-199707000-00006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Ernsberger P, Friedman JE, Koletsky RJ. The I1-imidazoline receptor: from binding site to therapeutic target in cardiovascular disease. JOURNAL OF HYPERTENSION. SUPPLEMENT : OFFICIAL JOURNAL OF THE INTERNATIONAL SOCIETY OF HYPERTENSION 1997; 15:S9-23. [PMID: 9050981 PMCID: PMC1351308 DOI: 10.1097/00004872-199715011-00002] [Citation(s) in RCA: 106] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
OBJECTIVE To review previous work and present additional evidence characterizing the I1-imidazoline receptor and its role in cellular signaling, central cardiovascular control, and the treatment of metabolic syndromes. Second-generation centrally-acting antihypertensives inhibit sympathetic activity mainly via imidazoline receptors, whereas first-generation agents act via alpha2-adrenergic receptors. The I1 subtype of imidazoline receptor resides in the plasma membrane and binds central antihypertensives with high affinity. METHODS AND RESULTS Radioligand binding assays have characterized I1-imidazoline sites in the brainstem site of action for these agents in the rostral ventrolateral medulla. Binding affinity at I1-imidazoline sites, but not at other classes of imidazoline binding sites, correlates closely with the potency of central antihypertensive agents in animals and in human clinical trials. The antihypertensive action of systemic moxonidine is eliminated by the I1/alpha2-antagonist efaroxan, but not by selective blockade of alpha2-adrenergic receptors. Until now, the cell signaling pathway coupled to I1-imidazoline receptors was unknown. Using a model system lacking alpha2-adrenergic receptors (PC12 pheochromocytoma cells) we have found that moxonidine acts as an agonist at the cell level and I1-imidazoline receptor activation leads to the production of the second messenger diacylglycerol, most likely through direct activation of phosphatidylcholine-selective phospholipase C. The obese spontaneously hypertensive rat (SHR; SHROB strain) shows many of the abnormalities that cluster in human syndrome X, including elevations in blood pressure, serum lipids and insulin. SHROB and their lean SHR littermates were treated with moxonidine at 8 mg/kg per day. SHROB and SHR treated with moxonidine showed not only lowered blood pressure but also improved glucose tolerance and facilitated insulin secretion in response to a glucose load. Because alpha2-adrenergic agonists impair glucose tolerance, I1-imidazoline receptors may contribute to the multiple beneficial effects of moxonidine treatment. CONCLUSION The I1-imidazoline receptor is a specific high-affinity binding site corresponding to a functional cell-surface receptor mediating the antihypertensive actions of moxonidine and other second-generation centrally-acting agents, and may play a role in countering insulin resistance in an animal model of metabolic syndrome X.
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Affiliation(s)
- P Ernsberger
- Department of Medicine, Case Western Reserve School of Medicine, Cleveland, Ohio 44106-4982, USA
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