Study of Droxidopa Treatment in Adults With Attention Deficit Hyperactivity Disorder With Co-administration of Carbidopa

Attention Deficit Hyperactivity Disorder (ADHD) is a neurobiological disorder characterized by lifelong issues of inattention, distraction, organizational difficulties, forgetfulness, restlessness, talking out of turn, difficulty waiting and interrupting others. ADHD is the second most common neuropsychiatric disorder affecting 4.4% of the United States (US) adult population, or between 8-9 million individuals. Droxidopa (L-dihydroxyphenylserine (L-DOPS)) is a synthetic catecholamine which is converted to norepinephrine (NE) via decarboxylation, resulting in increased levels of NE centrally in the central nervous system (CNS) and peripherally. Co-treatment with carboxylase inhibitors, such as carbidopa, given with droxidopa, can increase the CNS levels of NE with greater crossing of the blood-brain barrier. Droxidopa has received orphan drug approval by the Food and Drug Administration (FDA) for the treatment of symptomatic neurogenic orthostatic hypotension in individuals with primary autonomic failure. The half-life of droxidopa is approximately 2-3 hours, resulting in administration three times daily.