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

OBJECTIVE: To test whether the plasma levels of norepinephrine (NE) in patients with neurogenic orthostatic hypotension (nOH) predict their pressor response to droxidopa. METHODS: This was an observational study, which included patients with nOH. All patients had standardized autonomic function testing including determination of venous plasma catecholamine levels drawn through an indwelling catheter while resting supine. This was followed by a droxidopa titration with 100 mg increments in successive days until relief of symptoms, side effects, or the maximum dose of 600 mg was reached. No response was defined as an increase of <10 mm Hg in systolic blood pressure (BP) after 3-minute standing 1 hour after droxidopa administration. Nonlinear regression models were used to determine the relationship between BP response and plasma NE levels. RESULTS: We studied 20 patients with nOH due to Parkinson disease, pure autonomic failure, multiple system atrophy, or autoimmune autonomic neuropathies. Their supine plasma NE levels ranged from 44 to 850 pg/mL. Lower supine plasma NE levels were associated with greater pressor effect 1 hour after dose (R2 = 0.49) and higher standing BP (R2 = 0.45). Patients with no pressor response to droxidopa had higher NE levels (382 ± 100 vs 115 ± 20 pg/mL, p = 0.0014). A supine NE level of <219.5 pg/mL had 83% sensitivity and 93% specificity to predict a pressor response (area under the curve = 0.95, p = 0.0023). CONCLUSIONS: In patients with nOH, lower supine resting plasma NE levels are associated with a greater pressor effect of droxidopa treatment. This finding should help identify patients with nOH most likely to respond to standard doses of droxidopa. CLASSIFICATION OF EVIDENCE: This study provides Class I evidence that lower supine plasma NE levels accurately identify patients with nOH more likely to have a greater pressor effect from droxidopa.

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.

The Treatment of Primary Orthostatic Hypotension.

OBJECTIVE: To review the efficacy and safety of pharmacological and nonpharmacological strategies used to treat primary orthostatic hypotension (OH). DATA SOURCES: A literature review using PubMed and MEDLINE databases searching hypotension, non-pharmacological therapy, midodrine, droxidopa, pyridostigmine, fludrocortisone, atomoxetine, pseudoephedrine, and octreotide was performed. STUDY SELECTION AND DATA EXTRACTION: Randomized or observational studies, cohorts, case series, or case reports written in English between January 1970 and November 2016 that assessed primary OH treatment in adult patients were evaluated. DATA SYNTHESIS: Based on the chosen criteria, it was found that OH patients make up approximately 15% of all syncope patients, predominantly as a result of cardiovascular or neurological insults, or offending medication. Nonpharmacological strategies are the primary treatment, such as discontinuing offending medications, switching medication administration to bedtime, avoiding large carbohydrate-rich meals, limiting alcohol, maintaining adequate hydration, adding salt to diet, and so on. If these fail, pharmacotherapy can help ameliorate symptoms, including midodrine, droxidopa, fludrocortisone, pyridostigmine, atomoxetine, sympathomimetic agents, and octreotide. CONCLUSIONS: Midodrine and droxidopa possess the most evidence with respect to increasing blood pressure and alleviating symptoms. Pyridostigmine and fludrocortisone can be used in patients who fail to respond to these agents. Emerging evidence with low-dose atomoxetine is promising, especially in those with central autonomic failure, and may prove to be a viable alternative treatment option. Data surrounding other therapies such as sympathomimetic agents or octreotide are minimal. Medication management of primary OH should be guided by patient-specific factors, such as tolerability, adverse effects, and drug-drug and drug-disease interactions.

Safety and Durability of Effect with Long-Term, Open-Label Droxidopa Treatment in Patients with Symptomatic Neurogenic Orthostatic Hypotension (NOH303).

BACKGROUND: Neurogenic orthostatic hypotension (nOH) is associated with insufficient norepinephrine release in response to postural change. OBJECTIVE: The objective of this study was to evaluate the long-term safety and durability of efficacy of the norepinephrine precursor droxidopa in patients with symptomatic nOH. METHODS: This multinational study consisted of 3 sequential phases: a 3-month open-label droxidopa treatment phase followed by a 2-week double-blind, placebo-controlled withdrawal phase, and a 9-month open-label extension phase in which all patients received droxidopa. Patients were adults diagnosed with symptomatic nOH associated with Parkinson's disease, multiple system atrophy, pure autonomic failure, dopamine ß-hydroxylase deficiency, or nondiabetic autonomic neuropathy. Efficacy was evaluated using patient- and investigator-reported questionnaire responses and the orthostatic standing test. Safety was assessed through adverse event (AE) reports and vital signs. RESULTS: A total of 102 patients received treatment with droxidopa. Initial improvements from baseline in patient-reported nOH symptom severity and impact on daily activities, evaluated using the Orthostatic Hypotension Questionnaire, exceeded 50% and were maintained throughout the 12-month study. Decreased nOH severity was also reflected in clinician and patient ratings on the Clinical Global Impression questionnaire. Standing systolic and diastolic blood pressures were increased from baseline throughout the study with droxidopa treatment. The most frequently reported AEs were falls, urinary tract infection, and headache. There was a low incidence (≤2%) of cardiac AEs (eg, first-degree atrioventricular block, supraventricular extrasystoles). CONCLUSIONS: Long-term, open-label treatment with droxidopa for up to 12 months was generally well tolerated and provided durable improvements in nOH signs and symptoms.

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.

A randomized, double-blind, controlled trial of add-on therapy in moderate-to-severe Parkinson's disease.

OBJECTIVE: The primary objective was to evaluate the efficacy and safety of droxidopa as add-on therapy in improving stiffness, tremors and other motor functions and activities of daily living for moderate-to-severe Parkinson's disease (PD). METHODS: PD patients, above Hoehn-Yahr III (including Hoehn-Yahr III), were randomly assigned to drug therapy (droxidopa 600 mg/day for 8 weeks) or placebo. Efficacy indicators were the Unified Parkinson's Disease Rating Scale (UPDRS) part I, II, III subscale, Clinical Global Impression (CGI) rating score, and individual symptom scores (e.g. stiffness, tremors), to evaluate motor function and activities of daily life. RESULTS: There are 109 patients in the droxidopa group, and 110 in the placebo group, at baseline, there were no differences between the two groups for age, body weight, disease severity and previous drugs therapy. At days 14 and 57 of droxidopa add on treatment, UPDRS-II scores reflecting activities of daily life and UPDRS-III scores reflecting motor functions were significantly different compared to the pre-treatment baseline scores (P < 0.01), UPDRS- II and UPDRS-III scores at day 14 and day 57 were also significantly different (P < 0.01) between the two groups. Individual motor symptoms such as stiffness, resting tremor, and alternate hand motion were also significantly improved with droxidopa on days 14 and 57 of treatment (P < 0.01 vs placebo), showing that droxidopa is effective in improving rigidity, tremor and alternate motion of hand. CONCLUSIONS: Droxidopa was effective as symptomatic adjunct therapy, improved significantly motor function and activities of daily living, benefited patients with signs of tremor and Stiffness.

A randomized, placebo-controlled, phase 2 study of the efficacy and safety of droxidopa in patients with intradialytic hypotension.

INTRODUCTION: Intradialytic hypotension (IDH) is the most common complication of hemodialysis (HD), and it plays a significant role in the morbidity and mortality associated with maintenance HD. METHODS: This was a placebo-controlled, parallel-group study evaluating efficacy and safety of droxidopa in improving intradialytic blood pressure (BP) responses in 85 adults with end-stage renal disease (ESRD) and prone to IDH. Following screening and baseline periods, patients received 400 mg or 600 mg droxidopa, or placebo, orally 1 hour before HD for 4 weeks. Primary outcome endpoint was the change between baseline and last 2 treatment weeks in average mean arterial pressure (MAP) during HD. Also assessed were changes from baseline in systolic BP (SBP) and diastolic BP (DBP) during and after HD; number of hypotension-induced interventions and symptoms; and adverse events. RESULTS: Increase in droxidopa intra-HD MAP were not significantly different from placebo, although droxidopa groups showed significant improvements in mean SBP after HD of +4.8 ± 11.6 mm Hg (600-mg) and +3.4 ± 13.1 (400-mg) compared with -4.4 ± 17.9 mm Hg in placebo, and the drop seen in mean nadir SBP pre- to intra-HD was also reduced. Changes in mean DBP pre- and post-HD, changes in mean nadir SBP post-HD, or intra-HD SBP were not significant over the treatment period. HD terminations decreased 5-fold in the 600-mg group and 2-fold in the 400-mg group, whereas the number of discontinuations stayed unchanged in the placebo group. Overall, treatment with 600-mg or 400-mg droxidopa was well tolerated in this population. CONCLUSION: These data suggest that droxidopa may have a role in reducing IDH complications in patients with ESRD on chronic HD.

Droxidopa: a review of its use in symptomatic neurogenic orthostatic hypotension.

The norepinephrine prodrug droxidopa (NORTHERA™) is approved in the US for the treatment of orthostatic dizziness, lightheadedness, or the 'feeling that you are about to black out' in adults with symptomatic neurogenic orthostatic hypotension associated with primary autonomic failure (e.g. Parkinson's disease, multiple system atrophy or pure autonomic failure), dopamine ß-hydroxylase deficiency or nondiabetic autonomic neuropathy. This article reviews the clinical efficacy and tolerability of droxidopa in symptomatic neurogenic orthostatic hypotension, as well as summarizing its pharmacological properties. Oral droxidopa was effective in the shorter-term treatment of patients with symptomatic neurogenic orthostatic hypotension, with improvements seen in symptoms, the impact of symptoms on daily activities and standing systolic blood pressure. More data are needed to confirm the longer-term efficacy of droxidopa. Droxidopa was generally well tolerated, although patients should be monitored for supine hypertension.

Randomized withdrawal study of patients with symptomatic neurogenic orthostatic hypotension responsive to droxidopa.

UNLABELLED: We evaluated whether droxidopa, a prodrug converted to norepinephrine, is beneficial in the treatment of symptomatic neurogenic orthostatic hypotension, which results from failure to generate an appropriate norepinephrine response to postural challenge. Patients with symptomatic neurogenic orthostatic hypotension and Parkinson disease, multiple system atrophy, pure autonomic failure, or nondiabetic autonomic neuropathy underwent open-label droxidopa titration (100-600 mg, 3× daily). Responders then received an additional 7-day open-label treatment at their individualized dose. Patients were subsequently randomized to continue with droxidopa or withdraw to placebo for 14 days. We then assessed patient-reported scores on the Orthostatic Hypotension Questionnaire and blood pressure measurements. Mean worsening of Orthostatic Hypotension Questionnaire dizziness/lightheadedness score from randomization to end of study (the primary outcome; N=101) was 1.9±3.2 with placebo and 1.3±2.8 units with droxidopa (P=0.509). Four of the other 5 Orthostatic Hypotension Questionnaire symptom scores and all 4 symptom-impact scores favored droxidopa, with statistical significance for the patient's self-reported ability to perform activities requiring standing a short time (P=0.033) and standing a long time (P=0.028). Furthermore, a post hoc analysis of a predefined composite score of all symptoms (Orthostatic Hypotension Questionnaire composite) demonstrated a significant benefit for droxidopa (P=0.013). There was no significant difference between groups for standing systolic blood pressure (P=0.680). Droxidopa was well tolerated. In summary, this randomized withdrawal droxidopa study failed to meet its primary efficacy end point. Additional clinical trials are needed to confirm that droxidopa is beneficial in symptomatic neurogenic orthostatic hypotension, as suggested by the positive secondary outcomes of this trial. CLINICAL TRIAL REGISTRATION URL: http://www.clinicaltrials.gov. Unique identifier: NCT00633880.

Application of the BCS biowaiver approach to assessing bioequivalence of orally disintegrating tablets with immediate release formulations.

The aim of this study was to compare the dissolution profiles of oral disintegrating tablets (ODTs) and immediate release (IR) formulations in order to experimentally validate the regulatory biowaiver scheme (BWS) for biopharmaceutical classification system (BCS) class III drugs. We examined six drugs that show clinical bioequivalence between the ODTs and IR formulations: taltirelin, olopatadine, droxidopa, famotidine, fexofenadine, and hydrochlorothiazide. The dissolution profiles of these drugs were evaluated using the compendium paddle apparatus at pH 1.2 and 6.8. Taltirelin and olopatadine showed very rapid dissolution and met the dissolution criteria in the BWS, whereas droxidopa, famotidine, fexofenadine, and hydrochlorothiazide did not. Furthermore, in the case of famotidine, fexofenadine, and hydrochlorothiazide, the ODTs and IR formulations showed dissimilar dissolution profiles. The dose-to-solubility ratio (D:S) of these drugs was larger than that of the other drugs. The results of this study suggest that extension of the BCS-BWS to ODTs and IR formulations of BCS class III drugs is appropriate. Furthermore, for BCS class III drugs with relatively high D:S, clinical bioequivalence would be achievable even when two formulations showed different dissolution profiles in vitro.

Droxidopa for neurogenic orthostatic hypotension: a randomized, placebo-controlled, phase 3 trial.

OBJECTIVE: To determine whether droxidopa, an oral norepinephrine precursor, improves symptomatic neurogenic orthostatic hypotension (nOH). METHODS: Patients with symptomatic nOH due to Parkinson disease, multiple system atrophy, pure autonomic failure, or nondiabetic autonomic neuropathy underwent open-label droxidopa dose optimization (100-600 mg 3 times daily), followed, in responders, by 7-day washout and then a 7-day double-blind trial of droxidopa vs placebo. Outcome measures included patient self-ratings on the Orthostatic Hypotension Questionnaire (OHQ), a validated, nOH-specific tool that assesses symptom severity and symptom impact on daily activities. RESULTS: From randomization to endpoint (n = 162), improvement in mean OHQ composite score favored droxidopa over placebo by 0.90 units (p = 0.003). Improvement in OHQ symptom subscore favored droxidopa by 0.73 units (p = 0.010), with maximum change in "dizziness/lightheadedness." Improvement in symptom-impact subscore favored droxidopa by 1.06 units (p = 0.003), with maximum change for "standing a long time." Mean standing systolic blood pressure (BP) increased by 11.2 vs 3.9 mm Hg (p < 0.001), and mean supine systolic BP by 7.6 vs 0.8 mm Hg (p < 0.001). At endpoint, supine systolic BP >180 mm Hg was observed in 4.9% of droxidopa and 2.5% of placebo recipients. Adverse events reported in ≥ 3% of double-blind droxidopa recipients were headache (7.4%) and dizziness (3.7%). No patients discontinued double-blind treatment because of adverse events. CONCLUSIONS: In patients with symptomatic nOH, droxidopa improved symptoms and symptom impact on daily activities, with an associated increase in standing systolic BP, and was generally well tolerated. CLASSIFICATION OF EVIDENCE: This study provides Class I evidence that in patients with symptomatic nOH who respond to open-label droxidopa, droxidopa improves subjective and objective manifestation of nOH at 7 days.

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.