Viloxazine

Viloxazine (Qelbree) is one of the newer non-stimulant options for ADHD, approved in 2021 as an extended-release capsule for kids and adults alike. At its core it is a norepinephrine reuptake inhibitor, so it lifts noradrenergic tone in the prefrontal cortex much like atomoxetine does, but the interesting part is the serotonergic side: it also acts as a 5-HT2B antagonist and a 5-HT2C agonist, and that extra 5-HT modulation is thought to shape mood and its overall profile beyond plain norepinephrine.

Because it is not a releaser and not a controlled substance, it carries no meaningful abuse or dependence liability, which is a big part of the appeal for anyone who wants to steer clear of stimulants. It is also a repurposed molecule; it spent years as an old European antidepressant called Vivalan before being reborn for ADHD. It will not feel like the fast, obvious hit of an amphetamine; it builds over a couple of weeks, and common side effects include sleepiness, low appetite, and headache, plus a class warning to keep an eye on mood. Still, it is a genuinely useful non-stimulant to have in the toolkit.

Not a controlled substance and low in abuse potential, but not without risk. It carries an FDA boxed warning for increased risk of suicidal thoughts and behaviors, seen in both pediatric and adult trials, particularly early in treatment and after dose changes; patients, especially children and young adults, should be monitored for new or worsening mood changes, agitation, and emerging suicidality. Common side effects include somnolence, fatigue, decreased appetite, nausea, vomiting, insomnia, irritability, and headache.

It can modestly raise blood pressure and heart rate, so cardiovascular parameters are checked before and during treatment, and it may precipitate manic or hypomanic episodes in susceptible individuals. It is contraindicated with monoamine oxidase inhibitors and within fourteen days of stopping one, because of the risk of hypertensive crisis and serotonin toxicity. As a strong CYP1A2 inhibitor it is contraindicated or requires major dose reduction with sensitive CYP1A2 substrates such as duloxetine, theophylline, tizanidine, clozapine, olanzapine, and caffeine; it can also modestly raise levels of some CYP2D6 and CYP3A4 substrates. Doses are reduced in significant renal impairment.

Viloxazine is a strong inhibitor of cytochrome P450 1A2 (CYP1A2); in human subjects, it increases caffeine plasma AUC 5.83-fold, a classic marker of potent CYP1A2 inhibition ^[20]. Viloxazine inhibits the metabolism of antiepileptic drugs such as phenytoin and carbamazepine, raising their levels ^[21]. Common metabolic substrates such as warfarin, certain statins, and most benzodiazepines are not metabolized by CYP1A2 and thus avoid this interaction. The interaction potential with opioids, stimulant co-medications in ADHD, and most psychiatric combinations remains undocumented.

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Viloxazine, a bicyclic morpholine derivative loosely related in structure to the beta-blocker propranolol, was developed by Imperial Chemical Industries (ICI) and first marketed in Europe in the 1970s as an antidepressant under the trade name Vivalan. It served as an approved antidepressant across the United Kingdom and several European countries for roughly three decades before being withdrawn in the early 2000s for commercial reasons rather than efficacy or safety concerns.

Decades later, Supernus Pharmaceuticals repurposed the molecule as an extended-release noradrenergic agent for attention-deficit/hyperactivity disorder, running a program of Phase II and III pediatric, adolescent, and adult trials from roughly 2016 to 2020. The FDA approved the extended-release formulation as Qelbree for pediatric ADHD (ages 6 to 17) on April 2, 2021, followed by an adult ADHD indication in April 2022. Its arc from discontinued European antidepressant to modern non-stimulant ADHD therapy is a notable case of drug repurposing.