Supine plasma NE predicts the pressor response to droxidopa in neurogenic orthostatic hypotension

Effects of Atomoxetine for the Treatment of Neurogenic Orthostatic Hypotension in Patients With Alpha-synucleinopathies: A Systematic Review of Randomized Controlled Trials and a Focus-Group Discussion

BACKGROUND AND PURPOSE

Neurogenic orthostatic hypotension (nOH) is one of the most important nonmotor symptoms in patients with α-synucleinopathies. Atomoxetine is a selective norepinephrine transporter blocker that is a treatment option for nOH. This systematic review and expert focus-group study was designed to obtain evidence from published data and clinical experiences of Korean movement-disorder specialists about the efficacy and safety of atomoxetine for the pharmacological treatment of nOH in patients with α-synucleinopathies.

METHODS

The study comprised a systematic review and a focus-group discussion with clinicians. For the systematic review, multiple comprehensive databases including MEDLINE, Embase, Cochrane Library, CINAHL, PsycInfo, and KoreaMed were searched to retrieve articles that assessed the outcomes of atomoxetine therapy. A focus-group discussion was additionally performed to solicit opinions from experts with experience in managing nOH.

RESULTS

The literature review process yielded only four randomized controlled trials on atomoxetine matching the inclusion criteria. Atomoxetine effectively increased systolic blood pressure and improved OH-related symptoms as monotherapy or in combination with other drugs. Its effects were pronounced in cases with central autonomic failure, including multiple-system atrophy (MSA). Atomoxetine might be a safe monotherapy regarding the risk of supine hypertension.

CONCLUSIONS

Atomoxetine is an effective and safe option for short-term nOH management, which could be more evident in patients with central autonomic dysfunction such as MSA. However, there is a paucity of evidence in the literature, and data from the focus-group discussion were inadequate, and so further investigation is warranted.

Updates on the Diagnosis and Treatment of Peripheral Autonomic Neuropathies

PURPOSE OF REVIEW

Autonomic neuropathies are a complex group of disorders and result in diverse clinical manifestations that affect the cardiovascular, gastrointestinal, urogenital, and sudomotor systems. We focus this review on the diagnosis and treatment of peripheral autonomic neuropathies. We summarize the diagnostic tools and current treatment options that will help the clinician care for individuals with peripheral autonomic neuropathies.

RECENT FINDINGS

Autonomic neuropathies occur often in conjunction with somatic neuropathies but they can also occur in isolation. The autonomic reflex screen is a validated tool to assess sympathetic postganglionic sudomotor, cardiovascular sympathetic noradrenergic, and cardiac parasympathetic (i.e., cardiovagal) function. Initial laboratory evaluation for autonomic neuropathies includes fasting glucose or oral glucose tolerance test, thyroid function tests, kidney function tests, vitamin-B12, serum, and urine protein electrophoresis with immunofixation. Other laboratory tests should be guided by the clinical context. Reduced intraepidermal nerve density on skin biopsy is a finding, not a diagnosis. Skin biopsy can be helpful in selected individuals for the diagnosis of disorders affecting small nerve fibers; however, we strongly discourage the use of skin biopsy without clinical-physiological correlation. Ambulatory blood pressure monitoring may lead to early identification of patients with cardiovascular autonomic neuropathy in the primary care setting. Disease-modifying therapies should be used when available in combination with nonpharmacological management and symptomatic pharmacologic therapies. Autonomic function testing can guide the therapeutic decisions and document improvement with treatment. A systematic approach guided by the autonomic history and standardized autonomic function testing may help clinicians when identifying and/or counseling patients with autonomic neuropathies. Treatment should be individualized and disease-modifying therapies should be used when available.

Management of Orthostatic Hypotension in the Hospitalized Patient: A Narrative Review

Orthostatic hypotension is a frequent cause of falls and syncope, impairing quality of life. It is an independent risk factor of mortality and a common cause of hospitalizations, which exponentially increases in the geriatric population. We present a management plan based on a systematic literature review and understanding of the underlying pathophysiology and relevant clinical pharmacology. Initial treatment measures include removing offending medications and avoiding large meals. Clinical assessment of the patients' residual sympathetic tone can aid in the selection of initial therapy between norepinephrine "enhancers" or "replacers." Role of splanchnic venous pooling is overlooked, and applying abdominal binders to improve venous return may be effective. The treatment goal is not normalizing upright blood pressure but increasing it above the cerebral autoregulation threshold required to improve symptoms. Hypertension is the most common associated comorbidity, and confining patients to bed while using pressor agents only increases supine blood pressure, leading to worsening pressure diuresis and orthostatic hypotension. Avoiding bedrest deconditioning and using pressors as part of an orthostatic rehab program are crucial in reducing hospital stay.

Safety and efficacy of ampreloxetine in symptomatic neurogenic orthostatic hypotension: a phase 2 trial

PURPOSE

In neurogenic orthostatic hypotension, blood pressure falls when upright owing to impaired release of norepinephrine, leading to dizziness. Ampreloxetine, a selective norepinephrine reuptake inhibitor, increases circulating norepinephrine levels. This study explored the safety of ampreloxetine and its effect on blood pressure and symptoms in patients with neurogenic orthostatic hypotension.

METHODS

A multicenter ascending-dose trial (range 1-20 mg, Part A) was followed by a 1 day, double-blind, randomized, placebo-controlled study (median dose 15 mg, Part B). Eligible patients then enrolled in a 20-week, open-label, steady-state extension phase (median dose 10 mg, Part C) followed by a 4-week withdrawal. Assessments included the Orthostatic Hypotension Symptom Assessment Scale (item 1), supine/seated/standing blood pressure, and safety.

RESULTS

Thirty-four patients (age 66 ± 8 years, 22 men) were enrolled. Part A: The proportion of participants with a positive response (i.e., increase from baseline in seated systolic blood pressure of ≥ 10 mmHg) was greater with the 5 and 10 mg ampreloxetine doses than with placebo or other active ampreloxetine doses. Part B: Seated blood pressure increased 15.7 mmHg 4 h after ampreloxetine and decreased 14.2 mmHg after placebo [least squares mean difference (95% CI) 29.9 mmHg (7.6-52.3); P = 0.0112]. Part C: Symptoms of dizziness/lightheadedness improved 3.1 ± 3.0 points from baseline and standing systolic blood pressure increased 11 ± 12 mmHg. After 4 weeks of withdrawal, symptoms returned to pretreatment levels. The effect of ampreloxetine on supine blood pressure was minimal throughout treatment duration.

CONCLUSION

Ampreloxetine was well tolerated and improved orthostatic symptoms and seated/standing blood pressure with little change in supine blood pressure.

TRIAL REGISTRATION

NCT02705755 (first posted March 10, 2016).

Management of Orthostatic Hypotension in Parkinson's Disease

Orthostatic hypotension (OH) is a common non-motor feature of Parkinson's disease that may cause unexplained falls, syncope, lightheadedness, cognitive impairment, dyspnea, fatigue, blurred vision, shoulder, neck, or low-back pain upon standing. Blood pressure (BP) measurements supine and after 3 minutes upon standing screen for OH at bedside. The medical history and cardiovascular autonomic function tests ultimately distinguish neurogenic OH, which is due to impaired sympathetic nerve activity, from non-neurogenic causes of OH, such as hypovolemia and BP lowering drugs. The correction of non-neurogenic causes and exacerbating factors, lifestyle changes and non-pharmacological measures are the cornerstone of OH treatment. If these measures fail, pharmacological interventions (sympathomimetic agents and/or fludrocortisone) should be introduced stepwise depending on the severity of symptoms. About 50% of patients with neurogenic OH also suffer from supine and nocturnal hypertension, which should be monitored for with in-office, home and 24 h-ambulatory BP measurements. Behavioral measures help prevent supine hypertension, which is eventually treated with non-pharmacological measures and bedtime administration of short-acting anti-hypertensive drugs in severe cases. If left untreated, OH impacts on activity of daily living and increases the risk of syncope and falls. Supine hypertension is asymptomatic, but often limits an effective treatment of OH, increases the risk of hypertensive emergencies and, combined with OH, facilitates end-organ damage. A timely management of both OH and supine hypertension ameliorates quality of life and prevents short and long-term complications in patients with Parkinson's disease.

Predictors of the Pressor Response to the Norepinephrine Transporter Inhibitor, Atomoxetine, in Neurogenic Orthostatic Hypotension

[Figure: see text].

A practical approach to peripheral autonomic neuropathies

PURPOSE OF THE REVIEW

The review focuses on the practical evaluation and management of patients with autonomic neuropathies.

RECENT FINDINGS

Autonomic neuropathies are complex disorders and result in diverse clinical manifestations that affect the cardiovascular, gastrointestinal, urogenital, and sudomotor systems. The autonomic medical history is key when seeing a patient with suspected autonomic neuropathy. The history guides the clinical evaluation, laboratory testing, and autonomic testing in patients with autonomic neuropathies. The treatment of autonomic neuropathies is based on the combination of disease-modifying therapies, symptomatic pharmacologic therapies, and nonpharmacological management. Response to treatment can be assessed with quantitative autonomic biomarkers.

SUMMARY

Treatment of autonomic neuropathies should be individualized, guided by disease state, medications' mechanism of action and adverse event profile as well as cost. Genetic discoveries and pathologic understanding lead to the development of disease-modifying therapies as seen in familial amyloid polyneuropathy.

Pharmacokinetics and pharmacodynamics of ampreloxetine, a novel, selective norepinephrine reuptake inhibitor, in symptomatic neurogenic orthostatic hypotension

Purpose

Ampreloxetine is a novel, selective, long-acting norepinephrine reuptake (NET) inhibitor being investigated as a once-daily oral treatment for symptomatic neurogenic orthostatic hypotension (nOH) in patients with autonomic synucleinopathies. The purpose of this study was to characterize the pharmacokinetic and pharmacodynamic profiles of ampreloxetine in this target population.

Methods

Patients with nOH were enrolled in a multicenter, phase II clinical trial of ampreloxetine (NCT02705755). They received escalating doses over 5 days in the clinical research unit, followed by 20 weeks of open-label treatment and then a 4-week withdrawal. As neurochemical biomarkers of NET inhibition, we assayed plasma concentrations of norepinephrine (NE) and its main intraneuronal metabolite 3,4-dihydroxyphenylglycol (DHPG) pre- and post-ampreloxetine.

Results

Thirty-four patients with nOH were enrolled. Plasma ampreloxetine concentrations increased with repeated escalating doses, with peak concentrations observed 6–9 h post-drug administration. The median ampreloxetine dose in the 20-week treatment phase was 10 mg once daily. Plasma ampreloxetine concentrations reached steady state by 2 weeks, with stable plasma levels over 24 h. No influence of age or renal function on ampreloxetine plasma concentrations was observed. On treatment, compared to baseline, plasma NE significantly increased by 71% (p < 0.005), plasma DHPG significantly declined by 22% (p < 0.05), and the NE:DHPG ratio significantly increased (p < 0.001).

Conclusions

Persistent elevation of plasma NE levels accompanied by reduced DHPG levels after ampreloxetine suggests reduced neuronal reuptake and metabolism of NE in postganglionic efferent sympathetic neurons. The findings are consistent with long-lasting NET inhibition, which may increase vasoconstrictor tone, supporting once-daily ampreloxetine dosing in patients with nOH.

Management Strategies for Comorbid Supine Hypertension in Patients with Neurogenic Orthostatic Hypotension

PURPOSE OF REVIEW

In autonomic failure, neurogenic orthostatic hypotension (nOH) and neurogenic supine hypertension (nSH) are interrelated conditions characterized by postural blood pressure (BP) dysregulation. nOH results in a sustained BP drop upon standing, which can lead to symptoms that include lightheadedness, orthostatic dizziness, presyncope, and syncope. nSH is characterized by elevated BP when supine and, although often asymptomatic, may increase long-term cardiovascular and cerebrovascular risk. This article reviews the pathophysiology and clinical characteristics of nOH and nSH, and describes the management of patients with both nOH and nSH.

RECENT FINDINGS

Pressor medications required to treat the symptoms of nOH also increase the risk of nSH. Because nOH and nSH are hemodynamically opposed, therapies to treat one condition may exacerbate the other. The management of patients with nOH who also have nSH can be challenging and requires an individualized approach to balance the short- and long-term risks associated with these conditions. Approaches to manage neurogenic BP dysregulation include nonpharmacologic approaches and pharmacologic treatments. A stepwise treatment approach is presented to help guide neurologists in managing patients with both nOH and nSH.

Management of Orthostatic Hypotension

PURPOSE OF REVIEW

This article reviews the management of orthostatic hypotension with emphasis on neurogenic orthostatic hypotension.

RECENT FINDINGS

Establishing whether the cause of orthostatic hypotension is a pathologic lesion in sympathetic neurons (ie, neurogenic orthostatic hypotension) or secondary to other medical causes (ie, non-neurogenic orthostatic hypotension) can be achieved by measuring blood pressure and heart rate at the bedside. Whereas fludrocortisone has been extensively used as first-line treatment in the past, it is associated with adverse events including renal and cardiac failure and increased risk of all-cause hospitalization. Distinguishing whether neurogenic orthostatic hypotension is caused by central or peripheral dysfunction has therapeutic implications. Patients with peripheral sympathetic denervation respond better to norepinephrine agonists/precursors such as droxidopa, whereas patients with central autonomic dysfunction respond better to norepinephrine reuptake inhibitors.

SUMMARY

Management of orthostatic hypotension is aimed at improving quality of life and reducing symptoms rather than at normalizing blood pressure. Nonpharmacologic measures are the key to success. Pharmacologic options include volume expansion with fludrocortisone and sympathetic enhancement with midodrine, droxidopa, and norepinephrine reuptake inhibitors. Neurogenic supine hypertension complicates management of orthostatic hypotension and is primarily ameliorated by avoiding the supine position and sleeping with the head of the bed elevated.

Acute Sensory and Autonomic Neuronopathy: A Devastating Disorder Affecting Sensory and Autonomic Ganglia

Acute-onset and severe sensory and autonomic deficits with no motor dysfunction, typically preceded by a febrile illness, with poor recovery, and often fatal outcome are the hallmark features of acute sensory and autonomic neuronopathy (ASANN). Pathologically and electrophysiologically, ASANN is characterized by an extensive ganglionopathy affecting sensory and autonomic ganglia with preservation of motor neurons. Consequently, patients, usually children or young adult, develop acute-onset profound widespread loss of all sensory modalities resulting in automutilations, as well as autonomic failure causing neurogenic orthostatic hypotension, neurogenic underactive bladder, and gastroparesis and constipation. The diagnosis is clinical with support of nerve conduction studies and autonomic testing, as well as spinal cord magnetic resonance imaging showing characteristic posterior cord hyperintensities. Although the presumed etiology is immune-mediated, further studies are required to clarify the physiopathology of the disease. We here performed a systematic review of the epidemiology, pathophysiology, diagnosis, and management of ASANN, with three representative cases that recently presented at our clinic. All three patients had the typical clinical manifestations of ASANN but in different combinations, illustrating the variable phenotype of the disorder. Immunosuppression is seldom effective. Management options are limited to supportive and symptomatic care with the goal of minimizing complications and preventing death.

Spectrum of diabetic neuropathies

The diabetic state results in neuropathy. The main causative mechanism is hyperglycemia, although microvascular involvement, hypertriglyceridemia, as well as genetic and immune mechanisms may be contributory. There is a growing spectrum of types of diabetic neuropathies that differ based on the type of fibers involved (e.g. myelinated, unmyelinated, autonomic, somatic), distribution of nerves involved, and mechanisms of neuropathy. The most common type is distal sensory neuropathy (DSN), which affects the distal ends of large myelinated fibers, more often sensory than motor, and is often asymptomatic. The next-most common is distal small fiber neuropathy (DSFN), which largely affects the unmyelinated fibers and carries the phenotype of burning feet syndrome. Diabetic autonomic neuropathy (DAN) occurs when widespread involvement of autonomic unmyelinated fibers occurs, and patients can be incapacitated with orthostatic hypotension as well as neurogenic bladder and bowel involvement. Radiculoplexus diabetic neuropathy causes proximal weakness and pain, usually in the lower extremity, and has a combination of immune, inflammatory, and vascular mechanisms. The nerve roots and plexus are involved. These patients present with proximal weakness of a subacute onset, often with severe pain and some autonomic failure. Finally, rapid and sustained reduction of blood glucose can result in treatment-induced diabetic neuropathy (TIND), which largely affects the sensory and autonomic fibers. This occurs if HbA1c is rapidly reduced within 3 months, and the likelihood is proportional to the original A1c and the size of the reduction.

Managing autonomic dysfunction in Parkinson's disease: a review of emerging drugs

Introduction: Autonomic dysfunction is an integral part of Parkinson disease (PD) complex and can be seen both in early and advanced stages. There is a paucity of medicines available to manage autonomic dysfunction in PD and this adds to the considerable morbidity associated with the illness.Areas covered: The pathophysiology and the available therapeutic options of autonomic dysfunction seen in PD are discussed in detail. The potential targets for novel regimens are reviewed and the available literature on the drugs emerging in management of autonomic dysfunction in PD is highlighted.Expert opinion: In the current scenario, there are several drugs that can be tried for constipation viz stool laxatives, prucalopride, prokinetic agents and a high fiber diet. Bladder dysfunction has been treated with β-agonists and with mirabegron, a selective β-3 agonist, the anticholinergic side effects are minimized, and the drug has been found to be effective. Orthostatic hypotension is managed with midodrine while droxidopa is a new drug with promising efficacy. Botulinum toxin works best for management of sialorrhea, but repeated injections are needed.

Neurogenic Orthostatic Hypotension in Parkinson Disease: A Primer

Parkinson disease (PD) is associated with a variety of motor and non-motor clinical manifestations, including cardiovascular autonomic dysfunction. Neurogenic orthostatic hypotension (nOH) is a potentially serious manifestation of cardiovascular sympathetic failure that occurs in approximately 30% of patients with PD. Here we review the pathophysiology and effects of the condition as well as treatment considerations for patients with PD and nOH. Screening for nOH using orthostatic symptom questionnaires, orthostatic blood pressure measurements, and specialized autonomic testing is beneficial for the identification of symptomatic and asymptomatic cases because cardiac sympathetic denervation and nOH can occur even at early (premotor) stages of PD. Symptoms of nOH, such as orthostatic lightheadedness, in patients with PD, have been shown to adversely affect patient safety (with increased risk of falls) and quality of life and should prompt treatment with non-pharmacologic and, occasionally, pharmacologic measures. Patients with nOH are also at increased risk of supine hypertension, which requires balancing various management strategies. FUNDING: Lundbeck (Deerfield, IL).

Orthostatic Hypotension in Parkinson Disease

Orthostatic hypotension (OH) is a sustained fall in blood pressure on standing that can cause symptoms of organ hypoperfusion. OH is associated with increased morbidity and mortality and leads to a significant number of hospital admissions. OH can be caused by volume depletion, blood loss, cardiac pump failure, large varicose veins, medications, or defective activation of sympathetic nerves and reduced norepinephrine release upon standing. Neurogenic OH is a frequent and disabling problem in patients with synucleinopathies such as Parkinson disease, multiple system atrophy, and pure autonomic failure, and it is commonly associated with supine hypertension. Several therapeutic options are available.

Alpha-Synuclein Deposition Within Sympathetic Noradrenergic Neurons Is Associated With Myocardial Noradrenergic Deficiency in Neurogenic Orthostatic Hypotension

Lewy body diseases involve neurogenic orthostatic hypotension (nOH), cardiac noradrenergic deficiency, and deposition of the protein AS (alpha-synuclein) in sympathetic ganglion tissue. Mechanisms linking these abnormalities are poorly understood. One link may be AS deposition within sympathetic neurons. We validated methodology to quantify AS colocalization with TH (tyrosine hydroxylase), a marker of sympathetic noradrenergic innervation, and assessed associations of AS/TH colocalization with myocardial norepinephrine content and cardiac sympathetic neuroimaging data in nOH. Postmortem sympathetic ganglionic AS/TH colocalization indices and myocardial norepinephrine contents were measured in 4 Lewy body and 3 rare non-Lewy body nOH patients. Sixteen Lewy body and 11 non-Lewy body nOH patients underwent in vivo skin biopsies and thoracic 18F-dopamine positron emission tomographic scanning, with cutaneous colocalization indices expressed versus cardiac 18F-dopamine-derived radioactivity. Ganglionic AS/TH colocalization indices were higher and myocardial norepinephrine lower in Lewy body than non-Lewy body nOH ( P=0.0020, P=0.014). The Lewy body nOH group had higher AS/TH colocalization indices in skin biopsies and lower myocardial 18F-dopamine-derived radioactivity than did the non-Lewy body nOH group ( P<0.0001 each). All Lewy body nOH patients had colocalization indices >1.5 in skin biopsies and 18F-dopamine-derived radioactivity <6000 nCi-kg/cc-mCi, a combination not seen in non-Lewy body nOH patients ( P<0.0001). In Lewy body nOH, AS deposition in sympathetic noradrenergic nerves is related to postmortem neurochemical and in vivo neuroimaging evidence of myocardial noradrenergic deficiency. These associations raise the possibility that intraneuronal AS deposition plays a pathophysiological role in the myocardial sympathetic neurodegeneration attending Lewy body nOH.

Droxidopa for the treatment of neurogenic orthostatic hypotension in neurodegenerative diseases

INTRODUCTION

L-threo-3,4-dihydroxyphenylserine (droxidopa), a pro-drug metabolized to norepinephrine in nerve endings and other tissues, has been commercially available in Japan since 1989 for treating orthostatic hypotension symptoms in Parkinson's disease (PD) patients with a Hoehn & Yahr stage III rating, as well as patients with Multiple System Atrophy (MSA), familial amyloid polyneuropathy, and hemodialysis. Recently, the FDA has approved its use in symptomatic neurogenic orthostatic hypotension (NOH). Areas covered: The authors review the effects of droxidopa in NOH with a focus on the neurodegenerative diseases PD, MSA, and pure autonomic failure (PAF). Expert opinion: A few small and short placebo-controlled clinical trials in NOH showed significant reductions in the manometric drop in blood pressure (BP) after posture changes or meals. Larger Phase III studies showed conflicting results, with two out of four trials meeting their primary outcome and thus suggesting a positive yet short-lasting effect of the drug on OH Questionnaire composite score, light-headedness/dizziness score, and standing BP during the first two treatment-weeks. Results appear essentially similar in PD, MSA, and PAF. The FDA granted droxidopa approval in the frame of an 'accelerated approval program' provided further studies are conducted to assess its long-term effects on OH symptoms.