Integrated analysis of droxidopa trials for neurogenic orthostatic hypotension

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).

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

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.

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.

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