L-dihydroxyphenylserine (Droxidopa) in the treatment of orthostatic hypotension: the European experience

Total Synthesis of Eliglustat via Diastereoselective Amination of Chiral para-Methoxycinnamyl Benzyl Ether

Eliglustat (Cerdelga®, Genzyme Corp. Cambridge, MA, USA) is an approved drug for a non-neurological type of Gaucher disease. Herein, we describe the total synthesis of eliglustat 1 starting from readily available 1,4-benzodioxan-6-carbaldehyde via Sharpless asymmetric dihydroxylation and diastereoselective amination of chiral para-methoxycinnamyl benzyl ethers using chlorosulfonyl isocyanate as the key steps. Notably, the reaction between syn-1,2-dibenzyl ether 6 and chlorosulfonyl isocyanate in the mixture of toluene and hexane (10:1) afforded syn-1,2-amino alcohol 5 at a 62% yield with a diastereoselectivity > 20:1. This observation can be explained by competition between the SNi and the SN1 mechanisms, leading to the retention of stereochemistry.

The role of noradrenaline in cognition and cognitive disorders

Many aspects of cognition and behaviour are regulated by noradrenergic projections to the forebrain originating from the locus coeruleus, acting through alpha and beta adrenoreceptors. Loss of these projections is common in neurodegenerative diseases and contributes to their cognitive and behavioural deficits. We review the evidence for a noradrenergic modulation of cognition in its contribution to Alzheimer's disease, Parkinson's disease and other cognitive disorders. We discuss the advances in human imaging and computational methods that quantify the locus coeruleus and its function in humans, and highlight the potential for new noradrenergic treatment strategies.

Cardiology meets neurology: clinical presentation and management of patients with primary neurogenic disorders and orthostatic intolerance

Patients with primary neurogenic disorders such as pure autonomic failure or multiple system atrophy may initially present with cardiocirculatory symptoms such as orthostatic intolerance or fluctuations in heart rate with symptomatic tachycardia. It is therefore clinically important to identify such patients since circulatory manifestations are only one of a series of symptoms resulting from autonomic dysfunction in various organ systems. These patients require a multimodal diagnostic and therapeutic approach and should undergo extensive evaluation in a specialized autonomic nervous system (ANS) outpatient unit. Based on a clinical case presentation, the current review summarizes the diagnostic and therapeutic approach to key cardiovascular symptoms of primary autonomic disorders and their neurological work-up in a specialized autonomic function laboratory.

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.

Pilot Study of Droxidopa With Carbidopa in Adults With ADHD

OBJECTIVE

We conducted a two-period (open-label and double-blind) pilot investigation of droxidopa, with and without carbidopa, for ADHD.

METHOD

Twenty adult ADHD patients received open-label droxidopa titrated from 200 to 600 mg 3 times per day (TID; Weeks 1-3), then open-label droxidopa plus carbidopa titrated from 25 or 50 mg TID (Weeks 4-6). In Weeks 7 to 8, patients were randomized to continued co-treatment or matching placebo substitution.

RESULTS

Improvements in mean total Adult ADHD Investigator Symptom Report Scale (AISRS) scores were seen at Week 1 ( p < .0001) and Week 3 ( p < .0001). Improvements were maintained but not increased with carbidopa. Thirteen of 20 patients completed open-label treatment. In the double-blind period, mean total AISRS scores were similar between the co-treatment ( n = 6) and placebo ( n = 5) groups. No serious adverse events were reported.

CONCLUSION

These preliminary findings indicate that droxidopa can improve adult ADHD symptoms. Further studies are warranted to examine the efficacy and safety of droxidopa in ADHD.

Refractory orthostatic hypotension in a patient with a spinal cord injury: Treatment with droxidopa

CONTEXT

Orthostatic hypotension (OH) is a common complication in patients with a spinal cord injury, mainly affecting complete injuries above neurological level T6. It is generally more severe during the acute phase but can remain symptomatic for several years.

FINDINGS

A 65-year-old male with a grade ASIA A post-traumatic cervical spinal cord injury, at neurological level C4, presenting with symptomatic refractory OH. Increased blood pressure (BP) levels and an overall clinical improvement was observed after administering an increasing dose of droxidopa. Treatment was started at a dose of 100 mg twice daily (bid), one to be taken upon rising in the morning and another one in the afternoon, at least three hours before bedtime. According to the patient's symptomatic response, each individual dose was increased by 100 mg at 48-hour intervals. Both increased mean BP levels and a subjective symptomatic improvement were evidenced at a dose of 300 mg bid.

CLINICAL RELEVANCE

Treatment with droxidopa increases BP levels and improves symptoms related to refractory OH using all physical and pharmacological measures available. It could therefore constitute an effective alternative treatment for OH in patients with a spinal cord injury.

An update on emerging drugs for fibromyalgia treatment

INTRODUCTION

Fibromyalgia (FM) is a chronic disorder whose symptoms of pain, fatigue, sleep disturbances and depression have a devastating effect on patients' lives as it limits their ability to engage in everyday working and social activities, and make it difficult to maintain normal relationships with family, friends and employers. None of the currently available drugs are fully effective against the whole spectrum of symptoms. The aim of this narrative review is to summarise the data relating to the new therapeutic options that have become available over the last few years. Areas covered: Increasing efforts by the pharmaceutical industry have led to the introduction of new investigational drugs and new formulations of older drugs, and studies have been carried out in order to investigate the possibility of using drugs that are currently used for other diseases. Expert opinion: Slight improvements in the health of FM patients treated with drugs targeting a range of molecular mechanisms have been observed, but there is still no single drug that is capable of offering substantial efficacy against all of the characteristic symptoms of FM. The identification of new and improved therapies for FM requires consideration of the heterogeneity of the condition, which suggests the existence of different patient subgroups, a relationship between central and peripheral aspects of the pathophysiology, and the need for combined treatment with drugs targeting multiple molecular mechanisms.

Effectiveness of droxidopa compared to midodrine in standing blood pressure and orthostatic tolerance in adults with neurogenic orthostatic hypotension: a systematic review protocol

REVIEW QUESTION

The question of this review is: what is the effectiveness of droxidopa compared to midodrine on standing blood pressure and orthostatic intolerance symptoms in adults with neurogenic orthostatic hypotension?

Integrated analysis of droxidopa trials for neurogenic orthostatic hypotension

Background

Droxidopa, a prodrug of norepinephrine, was approved for treatment of neurogenic orthostatic hypotension (nOH) due to primary autonomic disorders based on 3 randomized double-blind studies. We performed safety and efficacy analyses of this pooled dataset (n = 460).

Methods

Efficacy was assessed using Orthostatic Hypotension Questionnaire (OHQ) scores (composite and individual items). Safety and tolerability were also examined.

Results

Droxidopa improved virtually all nOH symptom scores compared with placebo, significantly reducing OHQ composite score (−2.68 ± 2.20 vs −1.82 ± 2.34 units; P < 0.001), dizziness/lightheadedness score (−3.0 ± 2.9 vs −1.8 ± 3.1 units; P < 0.001), and 3 of 5 other symptom assessments (visual disturbances, weakness, and fatigue [P ≤ 0.010]). Droxidopa significantly improved 3 of 4 measures of activities of daily living (standing a long time, walking a short time, and walking a long time [P ≤ 0.003]) and significantly increased upright systolic blood pressure (11.5 ± 20.5 vs 4.8 ± 21.0 mmHg for placebo; P < 0.001). Droxidopa was effective in patients using inhibitors of dopa decarboxylase (DDCI; the enzyme that converts droxidopa to norepinephrine), but its efficacy was numerically greater in non-DDCI users. Droxidopa was well-tolerated. Rates of most adverse events were similar between groups. Supine hypertension rates were low, but slightly higher in patients receiving droxidopa (≤7.9% vs ≤4.6% for placebo); patients with severe hypertension at screening were excluded from these studies.

Conclusions

Droxidopa is effective for the treatment of nOH in patients with primary autonomic disorders and is generally well-tolerated. A longer trial is underway to confirm efficacy beyond the ≤2 to 10 - week period assessed in the current trials.

Trial registration

ClinicalTrials.gov identifiers: NCT00782340, first received October 29, 2008; NCT00633880, first received March 5, 2008; and NCT01176240, first received July 30, 2010.

New Horizons in orthostatic hypotension

Background

orthostatic hypotension (OH) is a common disabling condition associated with increased morbidity and mortality. Much of the evidence available is derived from younger populations with chronic neurological disease leading to uncertainty for the diagnosis and management of older people.

Objective

to provide an overview of recent and emerging evidence for the diagnosis, management and prognosis of OH in older persons.

Methods

a narrative review of recent studies, emerging therapies and relevant regulatory updates.

Findings

revisions to the diagnostic criteria for OH include the duration of the blood pressure drop, specific criteria for initial and delayed OH and OH with hypertension. Non-drug therapies remain the first-line treatment option and Comprehensive Geriatric Assessment appears to result in lower rates of OH. Recent evidence concerning withdrawal of causative medication is inconsistent. Midodrine has recently become the only licenced medication for OH in the UK. Other emerging treatments include atomoxetine and droxidopa but these require further evaluation. Many other agents may be used but are not supported by high-quality evidence. The increase in mortality associated with OH is less apparent in older people.

Summary

OH remains common in older people, the new diagnostic criteria address some of the previous uncertainty but evidence concerning withdrawal of antihypertensives is conflicting. Midodrine is now the only licenced medication for OH in the UK, but non-drug therapies remain first line and fludrocortisone may be considered before midodrine. We may see other agents such as droxidopa becoming increasingly used over the coming years.

Stability-Indicating Related Substances HPLC Method for Droxidopa and Characterization of Related Substances Using LC-MS and NMR

Stress degradation studies using high-performance liquid chromatography (HPLC) was performed and validated for Droxidopa (L-DOPS). Droxidopa was susceptible to acid hydrolysis (0.1 N HCl), alkaline hydrolysis (0.15 N NaOH) and thermal degradation (105°C). It was found to be resistant to white light, oxidation and UV light exposure (72 h). The thermal, acid and alkali degradation impurities were detected with the retention time (RT) of 12.7, 19.25 and 22.95 min. Our HPLC method detected process impurities (2R,3R)-2-amino-3-(3,4-dihydroxyphenyl)-3-hydroxypropionic acid (Impurity H), N-Hydroxypthalimide (Impurity N), (2R,3S)-2-amino-3-(benzo[d][1,3]dioxol-5-yl)-3-hydroxypropionic acid (Impurity L) and L-threo n-phthaloyl-3-(3, 4-dihydroxyphenyl)-serine (Intermediate) with RTs of 3.48, 15.5, 25.76 and 28.0 min. The related substances were further characterized and confirmed by liquid chromatography-mass spectroscopy (LC-MS), and nuclear magnetic resonance spectroscopy analysis. Our HPLC method detected up to 0.05 µg/mL of Droxidopa with S/N > 3.0 and quantified up to 0.10 µg /mL of Droxidopa with S/N ratio > 10.0. Droxidopa was highly stable for 12 h after its preparation for HPLC analysis. Our newly developed HPLC method was highly precise, specific, reliable and accurate for the analysis of Droxidopa and its related substances.

Fibromyalgia syndrome: novel therapeutic targets

Fibromyalgia syndrome (FMS) is a chronic disorder characterized by widespread pain and tenderness, accompanied by disturbed sleep, chronic fatigue and multiple additional functional symptoms. FMS continues to pose an unmet need regarding pharmacological treatment and many patients fail to achieve sufficient relief from existing treatments. As FMS is considered to be a condition in which pain amplification occurs within the CNS, therapeutic interventions, both pharmacological and otherwise, have revolved around attempts to influence pain processing in the CNS. In the current review, we present an update on novel targets in the search for effective treatment of FMS.

Neurogenic orthostatic hypotension: roles of norepinephrine deficiency in its causes, its treatment, and future research directions

BACKGROUND

Although a diversity of neurotransmitters and hormones participate in controlling blood pressure, norepinephrine released from postganglionic sympathetic nerve terminals is an important mediator of the rapid regulation of cardiovascular function required for homeostasis of cerebral perfusion. Hence, neurogenic orthostatic hypotension (NOH) often represents a deficiency of noradrenergic responsiveness to postural change.

RESEARCH DESIGN AND METHODS

PubMed searches with 'orthostatic hypotension' and 'norepinephrine' as conjoint search terms and no restriction on language or date, so as to survey the pathophysiologic and clinical relevance of norepinephrine deficiency for current NOH interventions and for future directions in treatment and research.

RESULTS

Norepinephrine deficiency in NOH can arise peripherally, due to cardiovascular sympathetic denervation (as in pure autonomic failure, Parkinson's disease, and a variety of neuropathies), or centrally, due to a failure of viscerosensory signals to generate adequate sympathetic traffic to intact sympathetic nerve endings (as in multiple system atrophy). Nonpharmacologic countermeasures such as pre-emptive water intake may yield blood-pressure increases exceeding those achieved pharmacologically. For patients with symptomatic NOH unresponsive to such strategies, a variety of pharmacologic interventions have been administered off-label on the basis of drug mechanisms expected to increase blood pressure via blood-volume expansion or vasoconstriction. Two pressor agents have received FDA approval: the sympathomimetic midodrine and more recently the norepinephrine prodrug droxidopa.

CONCLUSIONS

Pressor agents are important for treating symptomatic NOH in patients unresponsive to lifestyle changes alone. However, the dysautonomia underlying NOH often permits blood-pressure excursions toward both hypotension and hypertension. Future research should aim to shed light on the resulting management issues, and should also explore the possibility of pharmacotherapy selectively targeting orthostatic blood-pressure decreases.

Structural analysis of enzymes used for bioindustry and bioremediation

Microbial enzymes have been widely applied in the large-scale, bioindustrial manufacture of food products and pharmaceuticals due to their high substrate specificity and stereoselectivity, and their effectiveness under mild conditions with low environmental burden. At the same time, bioremedial techniques using microbial enzymes have been developed to solve the problem of industrial waste, particularly with respect to persistent chemicals and toxic substances. And finally, structural studies of these enzymes have revealed the mechanistic basis of enzymatic reactions, including the stereoselectivity and binding specificity of substrates and cofactors. The obtained structural insights are useful not only to deepen our understanding of enzymes with potential bioindustrial and/or bioremedial application, but also for the functional improvement of enzymes through rational protein engineering. This review shows the structural bases for various types of enzymatic reactions, including the substrate specificity accompanying cofactor-controlled and kinetic mechanisms.

New developments in the management of neurogenic orthostatic hypotension

Orthostatic hypotension (OH) is defined as a sustained reduction of ≥ 20 mmHg systolic blood pressure or ≥ 10 mmHg diastolic blood pressure upon standing for ≤ 3 min. Orthostatic hypotension is commonly associated with hypertension, and its prevalence is highest in those with uncontrolled hypertension compared to those with controlled hypertension or normotensive community elderly subjects. Orthostatic hypotension can cause significant disability, with patients experiencing dizziness, lightheadedness or syncope, and other problems that potentially have a profound negative impact on activities of daily living that require standing or walking. Furthermore, OH increases the risk of falls and, importantly, is an independent risk factor of mortality. Despite its importance, there is a paucity of treatment options for this condition. Most of the advances in treatment options have relied on small studies of repurposed drugs done in patients with severe OH due to rare neurodegenerative conditions. Midodrine, an oral prodrug converted to the selective α1-adrenoceptor agonist desglymidodrine, was approved by the FDA for the treatment of OH in 1996. For almost two decades, no other pharmacotherapy was developed specifically for the treatment of OH until 2014, when droxidopa was approved by the FDA for the treatment of neurogenic OH associated with primary autonomic neuropathies including Parkinson disease, multiple system atrophy, and pure autonomic failure. These are neurodegenerative diseases ultimately characterized by failure of the autonomic nervous system to generate norepinephrine responses appropriate to postural challenge. Droxidopa is a synthetic amino acid that is converted to norepinephrine by dopa-decarboxylase, the same enzyme that converts levodopa into dopamine in the treatment of Parkinson disease. We will review this and other advances in the treatment of OH in an attempt to provide a practical guide to its management.

Syncope due to Autonomic Dysfunction: Diagnosis and Management

Syncope is one of several disorders that cause transient loss of consciousness. Cerebral hypoperfusion is the proximate cause of syncope. Transient or fixed autonomic nervous system dysfunction is a major contributor in many causes. A structured approach to the evaluation of syncope allows for more effective therapy.

Structural optimization of SadA, an Fe(II)- and α-ketoglutarate-dependent dioxygenase targeting biocatalytic synthesis of N-succinyl-L-threo-3,4-dimethoxyphenylserine

L-threo-3,4-Dihydroxyphenylserine (l-DOPS, Droxidopa) is a psychoactive drug and synthetic amino acid precursor that acts as a prodrug to the neurotransmitters. SadA, a dioxygenase from Burkholderia ambifaria AMMD, is an Fe(II)- and α-ketoglutarate (KG)-dependent enzyme that catalyzes N-substituted branched-chain or aromatic l-amino acids. SadA is able to produce N-succinyl-l-threo-3,4-dimethoxyphenylserine (NSDOPS), which is a precursor of l-DOPS, by catalyzing the hydroxylation of N-succinyl-3,4-dimethoxyphenylalanine (NSDOPA). However, the catalytic activity of SadA toward NSDOPS is much lower than that toward N-succinyl branched-chain l-amino acids. Here, we report an improved biocatalytic synthesis of NSDOPS with SadA. Structure-based protein engineering was applied to improve the α-KG turnover activity for the synthesis of NSDOPS. The G79A, G79A/F261W or G79A/F261R mutant showed a more than 6-fold increase in activity compared to that of the wild-type enzyme. The results provide a new insight into the substrate specificity toward NSDOPA and will be useful for the rational design of SadA mutants as a target of industrial biocatalysts.

Management of neurogenic orthostatic hypotension in patients with autonomic failure

The maintenance of blood pressure in the upright position requires intact autonomic cardiovascular reflexes. Diseases that affect the sympathetic innervation of the cardiovascular system result in a sustained fall in blood pressure upon standing (i.e., neurogenic orthostatic hypotension) that can impair the blood supply to the brain and other organs and cause considerable morbidity and mortality. Here we review treatment options for neurogenic orthostatic hypotension and include an algorithm for its management that emphasizes the importance of non-pharmacologic measures and provides guidance on pharmacologic treatment options.

Orthostatic hypotension in patients with Parkinson's disease and atypical parkinsonism

Orthostatic hypotension (OH) is one of the commonly occurring nonmotor symptoms in patients with idiopathic Parkinson's disease (IPD) and atypical parkinsonism (AP). We aimed to review current evidences on epidemiology, diagnosis, treatment, and prognosis of OH in patients with IPD and AP. Major electronic medical databases were assessed including PubMed/MEDLINE and Embase up to February 2013. English-written original or review articles with keywords such as "Parkinson's disease," "atypical parkinsonism," and "orthostatic hypotension" were searched for relevant evidences. We addressed different issues such as OH definition, epidemiologic characteristics, pathophysiology, testing and diagnosis, risk factors for symptomatic OH, OH as an early sign of IPD, prognosis, and treatment options of OH in parkinsonian syndromes. Symptomatic OH is present in up to 30% of IPD, 80% of multiple system atrophy (MSA), and 27% of other AP patients. OH may herald the onset of PD before cardinal motor symptoms and our review emphasises the importance of its timely diagnosis (even as one preclinical marker) and multifactorial treatment, starting with patient education and lifestyle approach. Advancing age, male sex, disease severity, and duration and subtype of motor symptoms are predisposing factors. OH increases the risk of falls, which affects the quality of life in PD patients.

Orthostatic hypotension in Parkinson’s disease

SUMMARY Orthostatic hypotension (OH) is a frequent non-motor symptom in Parkinson’s disease (PD), affecting between 22.9 and 38.4% of patients. In PD, OH is related to an increased risk of falls, and possibly to cognitive dysfunction and increased mortality. These data emphasize the importance of its prompt recognition and treatment. OH is related to pre- and post-ganglionic adrenergic denervation, but other factors, such as drugs, heat, meals or alcohol intake, might also induce or aggravate it. Evidence about the efficacy and safety of pharmacological or nonpharmacological strategies for OH treatment in PD is weak. Nonpharmacological measures include liberal addition of salt to the diet, exercise, compression stockings or physical maneuvers. Severe cases may be treated with midodrine or fludrocortisone. Some results suggest that droxidopa and fipamezole may be effective treatments. We finish this review article by discussing the most important unanswered questions about PD-related OH, which may be the focus of future research.

L-DOPS and the treatment of neurogenic orthostatic hypotension

L-threo-dihydroxyphenylserine (L-DOPS) is an oral prodrug that is converted to the sympathetic neurotransmitter noradrenaline through a single-step decarboxylation by the endogenous enzyme 3,4-dihydrophenylalanine decarboxylase. DOPS can provide an exogenous source of noradrenaline to adrenergic neurons that are involved in the maintenance of blood pressure. Impaired secretion of noradrenaline at the synaptic junction can result in neurogenic orthostatic hypotension and cause faints and falls. The safety and efficacy of DOPS has been evaluated in patients with neurogenic orthostatic hypotension caused by a variety of neurological conditions that can result in autonomic failure, such as Parkinson’s disease, multiple system atrophy, pure autonomic failure and dopamine-β-hydroxylase deficiency. In this review, we include Phase II and III clinical trials undertaken that have examined the safety, efficacy and tolerability of DOPS in the treatment of neurogenic orthostatic hypotension. Drug mechanisms and pharmacology of the drug are also discussed.

The management of orthostatic hypotension in Parkinson's disease

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.

Update on the theory and management of orthostatic intolerance and related syndromes in adolescents and children

Orthostasis means standing upright. One speaks of orthostatic intolerance (OI) when signs, such as hypotension, and symptoms, such as lightheadedness, occur when upright and are relieved by recumbence. The experience of transient mild OI is part of daily life. 'Initial orthostatic hypotension' on rapid standing is a normal form of OI. However, other people experience OI that seriously interferes with quality of life. These include episodic acute OI, in the form of postural vasovagal syncope, and chronic OI, in the form of postural tachycardia syndrome. Less common is neurogenic orthostatic hypotension, which is an aspect of autonomic failure. Normal orthostatic physiology and potential mechanisms for OI are discussed, including forms of sympathetic hypofunction, forms of sympathetic hyperfunction and OI that results from regional blood volume redistribution. General and specific treatment options are proposed.

Hemodynamic effects of L-threo-3,4-dihydroxyphenylserine (Droxidopa) in hypotensive individuals with spinal cord injury

OBJECTIVES

To determine the effect of an escalating dose of droxidopa (100, 200, and 400 mg) compared with placebo on seated blood pressure (BP) in hypotensive individuals with spinal cord injury (SCI). Secondarily, we aimed to determine the effect of droxidopa on (1) supine BP and heart rate, (2) the change in BP and heart rate when these individuals were transferred from the supine to the seated position, and (3) adverse event (AE) reporting.

DESIGN

Open-label dose titration trial.

SETTING

A Veterans Administration Medical Center.

PARTICIPANTS

Participants with SCI (C3-T12) (N=10) were studied during 4 laboratory visits. Subjects visited the laboratory for about 5 hours on each visit, which incorporated a 30-minute seated baseline, a 30- to 60-minute supine, and a 4-hour seated postdrug observation.

INTERVENTIONS

Placebo on visit 1, droxidopa 100 mg on visit 2, droxidopa 200 mg on visit 3, and droxidopa 400 mg on visit 4.

MAIN OUTCOME MEASURES

BP and heart rate changes from baseline to the postdrug period, orthostatic heart rate and BP responses, and subjective AE reporting.

RESULTS

Seated BP was significantly elevated with 400 mg droxidopa compared with placebo and 100 mg droxidopa for 3 hours and was elevated for 2 hours compared with 200 mg droxidopa. Increase in supine BP was not worsened following droxidopa, and the expected fall in BP when transferred to the seated position was prevented with droxidopa 200 and 400 mg. There were no significant differences in the heart rate response or AE reporting among the study visits.

CONCLUSIONS

Our preliminary findings suggest that droxidopa, at the doses tested, does not cause excessive increases in supine BP and the 400-mg dose appears to be effective at increasing seated BP for up to 3 hours in persons with SCI.

Is there room for non-dopaminergic treatment in Parkinson disease?

Although levodopa and dopaminergic drugs remain the mainstay of therapy for the motor symptoms of Parkinson disease (PD), they fail to address many of the non-motor symptoms of PD including orthostatic hypotension, freezing of gait (FOG) and difficulty with balance, drug-induced paranoia and hallucinations, and drug-induced dyskinesias. Droxidopa, a drug that increases norepinephrine, treats orthostatic hypotension, cholinomimetic drugs sometimes help with FOG and difficulty with balance, pimavanserin, a drug that blocks serotonin receptors, treats paranoia and hallucinations, and anti-glutaminergic drugs treat dyskinesias. Thus, there are ample opportunities for non-dopaminergic drugs in PD.

Droxidopa, an oral norepinephrine precursor, improves hemodynamic and renal alterations of portal hypertensive rats

We aimed to evaluate the effects of droxidopa (an oral synthetic precursor of norepinephrine) on the hemodynamic and renal alterations of portal hypertensive rats. Sham, portal vein-ligated (PVL), and 4-week biliary duct-ligated (BDL) rats received a single oral dose of droxidopa (25-50 mg/kg) or vehicle and hemodynamic parameters were monitored for 2 hours. Two groups of BDL and cirrhotic rats induced by carbon tetrachloride (CCl(4) ) were treated for 5 days with droxidopa (15 mg/kg, twice daily, orally); hemodynamic parameters and blood and urinary parameters were assessed. The droxidopa effect on the Rho kinase (RhoK) / protein kinase B (AKT) / endothelial nitric oxide synthase (eNOS) pathways was analyzed by western blot in superior mesenteric artery (SMA). The acute administration of droxidopa in PVL and BDL rats caused a significant and maintained increase in arterial pressure and mesenteric arterial resistance, with a significant decrease of mesenteric arterial and portal blood flow, without changing portal pressure and renal blood flow. Two-hour diuresis greatly increased. Carbidopa (DOPA decarboxylase inhibitor) blunted all effects of droxidopa. Chronic droxidopa therapy in BDL rats produced the same beneficial hemodynamic effects observed in the acute study, did not alter liver function parameters, and caused a 50% increase in 24-hour diuresis volume (7.4 ± 0.9 mL/100g in BDL vehicle versus 11.8 ± 2.5 mL/100g in BDL droxidopa; P = 0.01). Droxidopa-treated rats also showed a decreased ratio of p-eNOS/eNOS and p-AKT/AKT and increased activity of RhoK in SMA. The same chronic treatment in CCl(4) rats caused similar hemodynamic effects and produced significant increases in diuresis volume and 24-hour natriuresis (0.08 ± 0.02 mmol/100g in CCl(4) vehicle versus 0.23 ± 0.03 mmol/100g in CCl(4) droxidopa; P = 0.014).

CONCLUSION

Droxidopa might be an effective therapeutic agent for hemodynamic and renal alterations of liver cirrhosis and should be tested in cirrhosis patients.

Upcoming treatments in Parkinson's disease, including gene therapy

Progress is being made in the development of three categories of therapy for Parkinson's disease: (1) Symptomatic, (2) Neuroprotective, (3) Neurorestorative. Evolving approaches to symptomatic therapy, already in clinical trials, include the use of adenosine 2(A) antagonists, novel glutamate antagonists, and serotonin receptor antagonists, the latter for the therapy of Parkinson's psychosis and/or levodopa-induced dyskinesias. Examples of promising neuroprotective therapies under evaluation include the administration of creatine, urate-inducing compounds, calcium channel blockers, and pioglitazone, a peroxisome proliferator-activated receptor agonist. Cell-based restorative therapies are not the subject of this presentation, but various forms of gene therapy have shown promise in human Parkinson's disease trials. These protocols typically involve gene transfer into the CNS through the use of viral vectors. Currently, the most advanced studies of this technique involve delivery of an adeno-associated viral vector encoding glutamic acid decarboxylase into the subthalamic nucleus. This treatment has shown modest benefit in early clinical trials. Other gene therapies, in various stages of human clinical trials, include gene transfer for the production of trophic factors, for aromatic amino acid decarboxylase alone, and most recently, a lentiviral vector transfer of an enzymatic dopamine "factory" consisting of three essential enzymes required for production for this neurotransmitter.

Norepinephrine: the next therapeutics frontier for Parkinson's disease

Tissue concentrations of norepinephrine (NE) are markedly decreased in various regions of the Parkinson's disease (PD) brain. As in the substantia nigra pars compacta, neuronal dropout and Lewy bodies are prominent changes affecting the locus coeruleus, which is the source of ascending NErgic projections. Despite the major roles of NE throughout the brain, there has been only minimal exploration of pharmacological intervention with NErgic neurotransmission. Cognitive operations, "freezing" of gait, tremor, dyskinesia, REM sleep regulation, and other aspects of brain function are tied into signaling by NE, and there is also evidence that it may have a role in the neurodegenerative process itself. This article reviews the reported pharmacological experience in PD therapeutics.

New insights into atypical parkinsonism

PURPOSE OF REVIEW

Atypical parkinsonian disorders (APDs) comprise a heterogenous group of disorders including multiple system atrophy (MSA), dementia with Lewy bodies (DLB), progressive supranuclear palsy (PSP) and corticobasal degeneration (CBD). Based on literature published in 2010, we here review recent advances in the APD field.

RECENT FINDINGS

Genome-wide association studies have provided robust evidence of increased disease risk conferred by synuclein and tau gene variants in MSA and PSP. Furthermore, advanced imaging tools have been established in the differential diagnosis and as surrogate markers of disease activity in patients with APDs. Finally, although therapeutic options are still disappointing, translational research into disease-modifying strategies has accelerated with the increasing availability of transgenic animal models, particularly for MSA.

SUMMARY

Remarkable progress has been achieved in the field of APDs, and advances in the genetics, molecular biology and neuroimaging of these disorders will continue to facilitate intensified clinical trial activity.

Multiple system atrophy: current and future approaches to management

Multiple system atrophy (MSA) is a rare neurodegenerative disorder without any effective treatment in slowing or stopping disease progression. It is characterized by poor levodopa responsive Parkinsonism, cerebellar ataxia, pyramidal signs and autonomic failure in any combination. Current therapeutic strategies are primarily based on dopamine replacement and improvement of autonomic failure. However, symptomatic management remains disappointing and no curative treatment is yet available. Recent experimental evidence has confirmed the key role of alpha-synuclein aggregation in the pathogenesis of MSA. Referring to this hypothesis, transgenic and toxic animal models have been developed to assess candidate drugs for MSA. The standardization of diagnosis criteria and assessment procedures will allow large multicentre clinical trials to be conducted. In this article we review the available symptomatic treatment, recent results of studies investigating potential neuroprotective drugs, and future approaches for the management in MSA.

The Movement Disorders task force review of dysautonomia rating scales in Parkinson's disease with regard to symptoms of orthostatic hypotension

Orthostatic hypotension is defined as a blood pressure fall of > 20 mm Hg systolic and/or 10 mm Hg diastolic within 3 minutes of an upright position. The Movement Disorders Society commissioned a task force to assess existing clinical rating scales addressing symptoms of orthostatic hypotension in Parkinson's disease. Seven neurologists and a clinimetrician assessed each scale's previous use and critiqued its clinimetric properties. A scale was "recommended" if it had been applied to populations of patients with Parkinson's disease, with data on its use in studies beyond the group that developed the scale, and was found to be clinimetrically valid. A scale was considered "suggested" if it had been applied to Parkinson's disease, but only 1 of the other criteria was applied. A scale was "listed" if it met only 1 criterion. Symptoms of orthostatic hypotension are generally assessed in scales on wider autonomic or nonmotor symptoms. Some scales designed to detect orthostatic hypotension-related symptoms provide information on their severity: the AUTonomic SCale for Outcomes in PArkinson's Disease and the COMPosite Autonomic Symptom Scale met criteria for recommended with some limitations; the Novel Non-Motor Symptoms Scale and the Orthostatic Grading Scale were classified as suggested. The Self-completed Non-Motor Symptoms Questionnaire for Parkinson's Disease was classified as suggested as a tool for screening orthostatic symptoms. However, these and the listed scales need further validation and application before they can be recommended for clinical use in patients with Parkinson's disease.

Pharmacological options in the management of orthostatic hypotension in older adults

Orthostatic hypotension (OH) is a common disorder in older adults with potentially serious clinical consequences. Understanding the key underlying pathophysiological processes that predispose individuals to OH is essential when making treatment decisions for this group of patients. In this article, we discuss the key antihypotensive agents used in the management of OH in older adults. Commonly, midodrine is used as a first-line agent, given its supportive data in randomized, controlled trials. Fludrocortisone has been evaluated in open-label trials and has long-established usage in clinical practice. Other agents are available and in clinical use, either alone or in combination, but larger randomized trial evaluations are yet to be published. It is important to bear in mind that a patient may be taking medications that predispose to or exacerbate the symptoms of OH. Withdrawal of such medications, where possible, should be considered before commencing other pharmacological agents that attenuate the symptoms of OH.