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 β-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.