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Gibbon JR, Frith J. The effects of caffeine in adults with neurogenic orthostatic hypotension: a systematic review. Clin Auton Res 2021; 31:499-509. [PMID: 34143333 PMCID: PMC8212790 DOI: 10.1007/s10286-021-00814-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2021] [Accepted: 06/12/2021] [Indexed: 01/27/2023]
Abstract
Purpose To systematically review the evidence base for the effectiveness and safety of caffeine for the treatment of neurogenic orthostatic hypotension in adults. Methods Eight electronic databases were searched in January 2021. Original research studies or case reports involving adults with neurogenic orthostatic hypotension were included if caffeine was an intervention and outcomes included symptoms, blood pressure or adverse effects. Relevant studies were screened and underwent qualitative analysis. Insufficient reporting precluded meta-analysis. Results Five studies were identified: four crossover studies and one case report summation. Study size ranged from 5 to 16 participants. Participants had neurogenic orthostatic hypotension, with a mean standing systolic blood pressure of 86 mmHg. Two studies evaluated caffeine alone. Three studies administered caffeine in combination with ergotamine. Caffeine dose ranged from 100 to 300 mg. Nature and timing of outcomes measured varied between studies, with measurements being recorded from 30 to 480 min after intervention. Caffeine/ergotamine improved symptoms in one study and reduced orthostatic blood pressure drop in two studies. Caffeine/ergotamine increased seated blood pressure in three studies, whilst the results for caffeine alone were inconsistent. No serious adverse events were reported. All studies demonstrated high risk of bias. Conclusion Caffeine should only be considered as a treatment for adults with neurogenic orthostatic hypotension when evidence-based treatments have been exhausted. Systematic review registration PROSPERO ID: CRD42020124589. Date of registration: 30/10/2020 Supplementary Information The online version contains supplementary material available at 10.1007/s10286-021-00814-5.
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Affiliation(s)
- Jake Ryan Gibbon
- Population Health Sciences Institute, Newcastle University, Newcastle Upon Tyne, UK.
| | - James Frith
- Population Health Sciences Institute, Newcastle University, Newcastle Upon Tyne, UK
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Banihani SA, Khaled HJ. Caffeine increased progressive motility of human spermatozoa in normozoospermic and asthenozoospermic semen samples and enhanced activity of seminal creatine kinase. Andrologia 2021; 53:e14052. [PMID: 33733465 DOI: 10.1111/and.14052] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2020] [Revised: 02/05/2021] [Accepted: 03/04/2021] [Indexed: 11/30/2022] Open
Abstract
Even though the effect of caffeine on humans' health has been revealed in various research studies, its effect on semen quality has yet to be well explained. Here, we measured the effect of caffeine at 1, 5, 10 and 20 mM on motility of human spermatozoa in normozoospermic and asthenozoospermic semen samples, level of seminal nitric oxide, chelation of seminal calcium ions and activity of seminal creatine kinase. Fifty-one normozoospermic and ten asthenozoospermic semen samples were recruited in this study. Sperm motility was evaluated by Makler counter, and seminal nitric oxide, seminal-free calcium and activity of seminal creatine kinase were measured spectrophotometrically. Caffeine at 10 mM significantly (p < .05) increased progressive motility of spermatozoa in both tested groups. Also, caffeine significantly increased (p < .05) activity of creatine kinase and insignificantly (p > .05) altered nitric oxide and free calcium levels in seminal plasma. In conclusion, progressive motility of human spermatozoa was found to be higher in the presence of caffeine at 10 mM in normozoospermic and asthenozoospermic semen samples; this increase, albeit partially, could be due to increased activity of seminal creatine kinase, but not to increased production of nitric oxide or chelation of free calcium ions.
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Affiliation(s)
- Saleem A Banihani
- Department of Medical Laboratory Sciences, Jordan University of Science and Technology, Irbid, Jordan
| | - Hebah J Khaled
- Department of Medical Laboratory Sciences, Jordan University of Science and Technology, Irbid, Jordan
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Abstract
Orthostatic hypotension (OH) leads to a significant number of hospitalizations each year, and is associated with significant morbidity and mortality among affected individuals. Given the increased risk for cardiovascular events and falls, it is important to identify the underlying etiology of OH and to choose appropriate therapeutic agents. OH can be non-neurogenic or neurogenic (arising from a central or peripheral lesion). The initial evaluation includes orthostatic vital signs, complete history and a physical examination. Patients should also be evaluated for concomitant symptoms of post-prandial hypotension and supine hypertension. Non-pharmacologic interventions are the first step for treatment of OH. The appropriate selection of medications can also help with symptomatic relief. This review highlights the pathophysiology, clinical features, diagnostic work-up and treatment of patients with neurogenic OH.
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Affiliation(s)
- Pearl K Jones
- a 1 Department of Neurology, University of Texas Health Sciences Center, San Antonio, TX, USA
| | - Brett H Shaw
- b 2 Department of Cardiac Science, Libin Cardiovascular Institute, University of Calgary, Calgary, AB, Canada
| | - Satish R Raj
- b 2 Department of Cardiac Science, Libin Cardiovascular Institute, University of Calgary, Calgary, AB, Canada.,c 3 Department of Medicine, Division of Clinical Pharmacology, Autonomic Dysfunction Center, Vanderbilt University, Nashville, Tennessee, USA
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Arnold AC, Ramirez CE, Choi L, Okamoto LE, Gamboa A, Diedrich A, Raj SR, Robertson D, Biaggioni I, Shibao CA. Combination ergotamine and caffeine improves seated blood pressure and presyncopal symptoms in autonomic failure. Front Physiol 2014; 5:270. [PMID: 25104940 PMCID: PMC4109567 DOI: 10.3389/fphys.2014.00270] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2014] [Accepted: 06/30/2014] [Indexed: 11/29/2022] Open
Abstract
Severely affected patients with autonomic failure require pressor agents to counteract the blood pressure fall and improve presyncopal symptoms upon standing. Previous studies suggest that combination ergotamine and caffeine may be effective in the treatment of autonomic failure, but the efficacy of this drug has not been evaluated in controlled trials. Therefore, we compared the effects of ergotamine/caffeine on seated blood pressure and orthostatic tolerance and symptoms in 12 primary autonomic failure patients without history of coronary artery disease. Patients were randomized to receive a single oral dose of placebo, midodrine (5–10 mg), or ergotamine and caffeine (1 and 100 mg, respectively) in a single-blind, crossover study. Blood pressure was measured while patients were seated and after standing for up to 10 min, at baseline and at 1 h post-drug. Ergotamine/caffeine increased seated systolic blood pressure (SBP), the primary outcome, compared with placebo (131 ± 19 and 95 ± 12 mmHg, respectively, at 1 h post-drug; p = 0.003 for time effect). Midodrine also significantly increased seated SBP (121 ± 19 mmHg at 1 h post-drug; p = 0.015 for time effect vs. placebo), but this effect was not different from ergotamine/caffeine (p = 0.621). There was no significant effect of either medication on orthostatic tolerance; however, ergotamine/caffeine improved presyncopal symptoms (p = 0.034). These findings suggest that combination ergotamine and caffeine elicits a seated pressor response that is similar in magnitude to midodrine, and improves symptoms in autonomic failure. Thus, ergotamine/caffeine could be used as an alternate treatment for autonomic failure, in carefully selected patients without comorbid coronary artery disease.
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Affiliation(s)
- Amy C Arnold
- Division of Clinical Pharmacology, Department of Medicine, Autonomic Dysfunction Center, Vanderbilt University School of Medicine Nashville, TN, USA
| | - Claudia E Ramirez
- Division of Clinical Pharmacology, Department of Medicine, Autonomic Dysfunction Center, Vanderbilt University School of Medicine Nashville, TN, USA
| | - Leena Choi
- Department of Biostatistics, Vanderbilt University School of Medicine Nashville, TN, USA
| | - Luis E Okamoto
- Division of Clinical Pharmacology, Department of Medicine, Autonomic Dysfunction Center, Vanderbilt University School of Medicine Nashville, TN, USA
| | - Alfredo Gamboa
- Division of Clinical Pharmacology, Department of Medicine, Autonomic Dysfunction Center, Vanderbilt University School of Medicine Nashville, TN, USA
| | - André Diedrich
- Division of Clinical Pharmacology, Department of Medicine, Autonomic Dysfunction Center, Vanderbilt University School of Medicine Nashville, TN, USA
| | - Satish R Raj
- Division of Clinical Pharmacology, Department of Medicine, Autonomic Dysfunction Center, Vanderbilt University School of Medicine Nashville, TN, USA
| | - David Robertson
- Division of Clinical Pharmacology, Department of Medicine, Autonomic Dysfunction Center, Vanderbilt University School of Medicine Nashville, TN, USA
| | - Italo Biaggioni
- Division of Clinical Pharmacology, Department of Medicine, Autonomic Dysfunction Center, Vanderbilt University School of Medicine Nashville, TN, USA
| | - Cyndya A Shibao
- Division of Clinical Pharmacology, Department of Medicine, Autonomic Dysfunction Center, Vanderbilt University School of Medicine Nashville, TN, USA
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5
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Management of neurogenic orthostatic hypotension. J Am Med Dir Assoc 2014; 15:234-9. [PMID: 24388946 DOI: 10.1016/j.jamda.2013.10.014] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2013] [Revised: 10/25/2013] [Accepted: 10/25/2013] [Indexed: 11/20/2022]
Abstract
The burden of orthostatic hypotension (OH) on public health is a universally recognized enigmatic clinical condition that is associated with significant increases on morbidity and mortality rates, and can take a major toll on one's quality of life. Orthostatic hypotension is predictive of vascular deaths from acute myocardial infarction, strokes in the middle aged population, and increases mortality rates when associated with diabetes, hypertension, Parkinson's disease, and patients receiving renal dialysis. The consensus definition for OH is a fall in systolic blood pressure of at least 20 mm Hg and/or diastolic blood pressure of at least 10 mm Hg within 3 minutes of quiet standing. Because neurogenic OH is often accompanied by supine hypertension, the treatment program should aim toward minimizing OH and the potential fall injuries related to cerebral hypoperfusion without exacerbating nocturnal hypertension that may lead to excessive cardiovascular complications.
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Sánchez-Ferro A, Benito-León J, Gómez-Esteban JC. The management of orthostatic hypotension in Parkinson's disease. Front Neurol 2013; 4:64. [PMID: 23772219 PMCID: PMC3677136 DOI: 10.3389/fneur.2013.00064] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2013] [Accepted: 05/19/2013] [Indexed: 12/23/2022] Open
Abstract
Orthostatic hypotension (OH) is a common and disabling symptom affecting Parkinson's disease (PD) patients. We present the effect of the different therapies commonly used to manage PD on this clinical manifestation. For this purpose, we describe the relationship between OH and the current treatments employed in PD, such as L-DOPA, dopaminergic agonists, and continuous dopaminergic stimulation therapies. Additionally, we review the therapeutic measures that could be used to ameliorate OH. There are different approaches to deal with this manifestation, including pharmacological and non-pharmacological treatments, although none of them is specifically aimed for treating OH in PD.
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Affiliation(s)
- Alvaro Sánchez-Ferro
- Department of Neurology, University Hospital "12 de Octubre," Madrid , Spain ; Department of Medicine, Faculty of Medicine, Complutense University , Madrid , Spain ; Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas , Madrid , Spain ; Instituto de Salud Carlos III , Madrid , Spain
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Shibao C, Okamoto L, Biaggioni I. Pharmacotherapy of autonomic failure. Pharmacol Ther 2011; 134:279-86. [PMID: 21664375 DOI: 10.1016/j.pharmthera.2011.05.009] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2011] [Accepted: 05/13/2011] [Indexed: 10/18/2022]
Abstract
The clinical picture of autonomic failure is characterized by severe and disabling orthostatic hypotension. These disorders can develop as a result of damage of central neural pathways or peripheral autonomic nerves, caused either by a primary autonomic neurodegenerative disorder or secondary to systemic illness. Treatment should be focused on decreasing pre-syncopal symptoms instead of achieving blood pressure goals. Non-pharmacologic strategies such as physical counter-maneuvers, dietary changes (i.e. high salt diet, rapid water drinking or compression garments) are the first line therapy. Affected patients should be screened for co-morbid conditions such as post-prandial hypotension and supine hypertension that can worsen orthostatic hypotension if not treated. If symptoms are not controlled with these conservative measures the next step is to start pharmacological agents; these interventions should be aimed at increasing intravascular volume either by promoting water and salt retention (fludrocortisone) or by increasing red blood cell mass when anemia is present (recombinant erythropoietin). When pressor agents are needed, direct pressor agents (midodrine) or agents that potentiate sympathetic activity (atomoxetine, yohimbine, pyridostigmine) can be used. It is preferable to use short-acting pressor agents that can be taken on as needed basis in preparation for upright activities.
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Affiliation(s)
- Cyndya Shibao
- Department of Medicine, Division of Clinical Pharmacology and the Autonomic Dysfunction Center, Vanderbilt University School of Medicine, Nashville, TN 37212, USA
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Abstract
SummaryThe autonomic nervous system comprises the sympathetic, parasympathetic and enteric nervous systems and plays an integral role in homeostasis. This includes cardiovascular and temperature control, glucose metabolism, gastrointestinal and reproductive function and increasing evidence to support its involvement in the inflammatory response to infection and cancer. Ageing is associated with autonomic dysfunction, and many clinical syndromes associated with older adults are due to inadequate autonomic responses to physiological stressors. The aim of this review is to explore the relationship between autonomic dysfunction and ageing illustrated with examples of maladaptive autonomic responses in a variety of different clinical syndromes including an exploration of autonomic cellular changes. Appropriate investigation and management strategies are outlined, recognizing the fine balance needed to improve symptoms without creating further medical complications.
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Abstract
Although extrapyramidal diseases are commonly thought to solely affect the extrapyramidal motor system, nonmotor symptoms such as behavioural abnormalities, dysautonomia, sleep disturbances and sensory dysfunctions are also frequently observed. Autonomic dysfunction as an important clinical component of extrapyramidal disease (idiopathic Parkinson's disease, multiple system atrophy, progressive supranuclear palsy, dementia with Lewy bodies) is often not formally assessed and thus frequently misdiagnosed. Symptoms of autonomic dysfunction in general impact more on quality of life than motor symptoms. Appropriate symptom-oriented diagnosis and symptomatic treatment as part of an interdisciplinary approach can greatly benefit the patient. Unfortunately, double-blind, randomized, controlled studies are scarce with the consequence that most recommendations are not based on the highest level of evidence. This review elaborates a limited overview on the treatment of cardiovascular, gastrointestinal, urogenital and sudomotor autonomic dysfunction in various extrapyramidal syndromes.
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Affiliation(s)
- Tjalf Ziemssen
- ANF Laboratory, Department of Neurology, University Clinic Carl Gustav Carus, Dresden University of Technology, Dresden, Germany
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Abstract
Orthostatic hypotension (OH) occurs in 0.5% of individuals and as many as 7-17% of patients in acute care settings. Moreover, OH may be more prevalent in the elderly due to the increased use of vasoactive medications and the concomitant decrease in physiologic function, such as baroreceptor sensitivity. OH may result in the genesis of a presyncopal state or result in syncope. OH is defined as a reduction of systolic blood pressure (SBP) of at least 20 mm Hg or diastolic blood pressure (DBP) of at least 10 mm Hg within 3 minutes of standing. A review of symptoms, and measurement of supine and standing BP with appropriate clinical tests should narrow the differential diagnosis and the cause of OH. The fall in BP seen in OH results from the inability of the autonomic nervous system (ANS) to achieve adequate venous return and appropriate vasoconstriction sufficient to maintain BP. An evaluation of patients with OH should consider hypovolemia, removal of offending medications, primary autonomic disorders, secondary autonomic disorders, and vasovagal syncope, the most common cause of syncope. Although further research is necessary to rectify the disease process responsible for OH, patients suffering from this disorder can effectively be treated with a combination of nonpharmacologic treatment, pharmacologic treatment, and patient education. Agents such as fludrocortisone, midodrine, and selective serotonin reuptake inhibitors have shown promising results. Treatment for recurrent vasovagal syncope includes increased salt and water intake and various drug treatments, most of which are still under investigation.
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Abstract
BACKGROUND Symptomatic postural hypotension in diabetes is uncommon. When it does occur, it can prove debilitating and difficult to treat. We report here the therapeutic challenges encountered in managing a patient with severe postural hypotension secondary to diabetes-related autonomic neuropathy. CASE REPORT A 69-year-old gentleman with a 23-year history of Type 1 diabetes mellitus and multiple microvascular complications was admitted with symptoms of severe postural hypotension. Cardiovascular autonomic testing confirmed the presence of severe autonomic neuropathy. He failed to respond to non-pharmacological measures, fludrocortisone, midodrine, octreotide, erythropoietin and increased caffeine intake. Eventually he was commenced on half a Cafergot suppository (giving him a dose of ergotamine 1 mg and caffeine 50 mg) which resulted in dramatic clinical improvement. CONCLUSION Ergotamine may be considered in refractory cases of postural hypotension.
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Affiliation(s)
- V Toh
- Oxford Centre of Diabetes, Endocrinology and Metabolism, Churchill Hospital, Oxford, UK.
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12
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Abstract
We discuss 2 cases presenting clinically with disabling orthostatic hypotension and severe supine hypertension. This is a common presentation of autonomic failure, and one that challenges conventional treatment. Clinical findings of isolated autonomic failure were the most prominent manifestation in case 1, whereas a movement disorder was the key finding in case 2. The differential diagnosis and treatment of orthostatic hypotension is discussed from a pathophysiological approach. Understanding of the underlying mechanisms of disorders of the autonomic nervous system is fundamental for an effective management of these patients and provides insight into more common disorders such as essential hypertension.
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Affiliation(s)
- Cyndya Shibao
- Division of Clinical Pharmacology, Department of Medicine and Pharmacology, and the Autonomic Dysfunction Center, Vanderbilt University School of Medicine, Nashville, Tenn 37212, USA
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13
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Affiliation(s)
- Richard B Dewey
- Department of Neurology, University of Texas Southwestern Medical School, 5323 Harry Hines Boulevard, Dallas, TX 75390, USA.
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Siebert U, Bornschein B, Walbert T, Dodel RC. Systematic assessment of decision models in Parkinson's disease. VALUE IN HEALTH : THE JOURNAL OF THE INTERNATIONAL SOCIETY FOR PHARMACOECONOMICS AND OUTCOMES RESEARCH 2004; 7:610-626. [PMID: 15367256 DOI: 10.1111/j.1524-4733.2004.75012.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
OBJECTIVE To give an insight into the structural and methodological approaches used in published decision-analytic models evaluating interventions in Parkinson's disease (PD) and to derive recommendations for future comprehensive PD decision models. METHODS A systematic literature review was performed to identify studies that evaluated PD interventions using mathematical decision models. Using a standardized assessment form, information on the study design, methodological framework, and data sources was extracted from each publication and systematically reported. Strengths and limitations were assessed. RESULTS We identified eight studies that used mathematical models to evaluate different pharmaceutical (n=7) and surgical (n=1) treatment options in PD. All models included economic evaluations. Modeling approaches comprised mathematical equations, decision trees, and Markov models with a time horizon ranging from 5 years to lifetime. All based progression on the evolution of clinical surrogate endpoints. Treatment effects were either modeled via reduction of symptomatic progression and/or initial symptomatic improvement or via reduction of adverse effect rates. No model is currently available that encompasses both the underlying biologic disease progression and the spectrum of all relevant complications and also links them to patient preferences and economic outcomes. CONCLUSIONS Models have been successfully applied to evaluate PD treatments. However, currently available models have substantial limitations. We recommend that a comprehensive, generic, and flexible decision model for PD that can be applied to different treatment strategies should consider a large spectrum of clinically relevant outcomes and complications of the disease during a sufficiently long time horizon, include PD-specific mortality, systematically evaluate uncertainty including heterogeneity effects, and should be validated by independent data or other models. Approaches to model treatment effects included reduction of symptomatic progression, initial symptomatic improvement, or reduction of adverse effects. We believe that structural bias could be avoided if underlying disease progression and treatment effects on symptoms are modeled separately.
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Affiliation(s)
- Uwe Siebert
- Institute for Technology Assessment and Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
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Lamarre-Cliche M. Drug treatment of orthostatic hypotension because of autonomic failure or neurocardiogenic syncope. Am J Cardiovasc Drugs 2004; 2:23-35. [PMID: 14727996 DOI: 10.2165/00129784-200202010-00004] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Orthostatic hypotension either because of autonomic failure or neurocardiogenic syncope can be very incapacitating and should be treated accordingly. Drug therapy is frequently needed to alleviate orthostatic symptoms. The physiopathological basis of neurocardiogenic syncope and of autonomic failure is completely different and their treatment should be distinct. In the past 5 years, many randomized, placebo-controlled trials have shed light on the efficacy of specific pressor drugs. In patients with orthostatic hypotension because of autonomic failure, alpha-adrenoceptor agonists, and midodrine in particular, have been shown to increase standing blood pressure and decrease orthostatic symptoms. Other drugs such as octreotide, indomethacin or ergotamine have also been shown to elevate standing blood pressure and/or orthostatic tolerance. Fludrocortisone is a well known and frequently used pressor drug but randomized controlled studies are needed to measure its efficacy. In patients with orthostatic hypotension associated with neurocardiogenic syncope, clinical trials have demonstrated that beta-blockers, especially beta(1)-selective agents without intrinsic sympathomimetic activity such as atenolol, midodrine and paroxetine can decrease recurrence of syncope. Treatment algorithms, such as those presented in this review, should always be interpreted in the light of individual patient characteristics. Many of the drugs used for orthostatic hypotension have multiple indications and contraindications that should influence therapeutic decisions. Little is known about the effectiveness and tolerability of specific combinations of pressor drugs. Consequently, sound clinical judgment and close follow-up of patients should always guide combination therapy.
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Maule S, Tredici M, Del Colle S, Chiandussi L. Treatment of Patients with Neurogenic Orthostatic Hypotension. High Blood Press Cardiovasc Prev 2003. [DOI: 10.2165/00151642-200310020-00007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022] Open
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Victor RG, Talman WT. Comparative effects of clonidine and dihydroergotamine on venomotor tone and orthostatic tolerance in patients with severe hypoadrenergic orthostatic hypotension. Am J Med 2002; 112:361-8. [PMID: 11904110 DOI: 10.1016/s0002-9343(02)01023-9] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
PURPOSE Clonidine, an alpha(2)-adrenergic agonist, raises blood pressure in patients with autonomic failure, in whom failure of reflex neurogenic venoconstriction leads to severe orthostatic hypotension. Because animal studies suggest that postjunctional alpha(2)-adrenoreceptors are located mainly on venous capacitance rather than arterial resistance vessels, we tested the hypothesis that venoconstriction is the main mechanism by which clonidine raises blood pressure in patients with autonomic failure. SUBJECTS AND METHODS We measured forearm venous and arterial tone using plethysmography in 4 patients with autonomic failure before and after acute administration of clonidine (0.4 mg orally) or dihydroergotamine (0.15 mg intravenously), a known venoconstrictor agent. We also recorded supine intraarterial pressure at rest and during graded orthostatic stress with lower body negative pressure. RESULTS Clonidine and dihydroergotamine caused similar increases in supine (mean +/- SD) arterial pressure (+23 +/- 11 mm Hg vs. and +27 +/- 5 mm Hg) and forearm vascular resistance (+36% +/- 13% vs. +28% +/- 9%). However, the drugs had different effects on forearm venous tone, which increased by 38% +/- 9% with dihydroergotamine (P = 0.01 vs. control) but was unaffected by clonidine (change = 0% +/- 14%). A single dose of clonidine was less effective than a single dose of dihydroergotamine in maintaining arterial pressure during graded orthostatic stress. CONCLUSION In contrast with what has been hypothesized, clonidine appears to function mainly as an arterial constrictor in patients with hypoadrenergic orthostatic hypotension. Further studies are needed to determine if venoconstrictor agents are of greater therapeutic benefit in this condition than are pure arterial vasoconstrictors.
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Affiliation(s)
- Ronald G Victor
- Donald W. Reynolds Clinical Cardiovascular Research Center, Department of Internal Medicine, Hypertension Division, University of Texas Southwestern Medical Center at Dallas, 5323 Harry Hines Boulevard, Dallas, TX 75235-8586, USA
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