Viloxazine HCl powder

What is Viloxazine HCl powder

Viloxazine is a bicyclic morpholine derivative synthesised at ICI in the 1970s under the code ICI 58,834. We supply it as the hydrochloride (CAS 35604-67-2) — the same salt used both in research and in the approved medicine.

An unusual career. In Europe viloxazine was sold as an antidepressant under the names Vivalan and Vicilan, then withdrawn for commercial reasons. Decades later it was revisited — and in April 2021 the FDA approved it for ADHD under the name Qelbree (FDA / DailyMed). Few compounds travel the road from forgotten antidepressant to approved therapy from a standing start.

Target and figures. Viloxazine inhibits the norepinephrine transporter (NET) with an IC₅₀ of 0.26 µM, competitively blocking reuptake and raising norepinephrine and dopamine levels in the synaptic cleft (MedChemExpress).

The other half of the profile is serotonergic. This is what separates viloxazine from "clean" NRIs such as atomoxetine: it is simultaneously a 5-HT₂B antagonist (K_i 4.2 µM) and a 5-HT₂C agonist (EC₅₀ 32 µM), modulating serotonergic transmission through two distinct subtype targets (MedChemExpress). Because of this duality the compound is classed under its own term — a serotonin norepinephrine modulating agent (Sigma-Aldrich).

Why it is not equivalent to atomoxetine. Viloxazine's affinity for NET is moderate rather than extreme, and it is precisely the combination of moderate transporter blockade with 5-HT₂B/₂C activity that produces a profile no selective inhibitor reproduces. Experimentally this means viloxazine cannot be swapped for a "stronger" NRI — the nature of the intervention itself would change.

Clean profile. In comparative studies viloxazine, unlike the other compounds tested in the same series, showed no anticholinergic activity at all (Wikipedia). For a class historically built on tricyclics with their burden of off-targets, this is a fundamental distinction.

Stereochemistry. The compound is racemic, but the isomers are not equivalent: the S-(−) form is roughly five times more active than the R-(+). A classic illustration of one half of a racemate carrying most of the effect.

Pharmacokinetics. Absolute oral bioavailability is around 85%, peak concentration is reached in about 2 hours, and the elimination half-life is roughly 4.3 hours. It is this short half-life that drove development of the extended-release form known by the code SPN-812.

Solubility. The hydrochloride is readily soluble in water and in aqueous solutions up to pH 9.5, and sparingly soluble in methanol (FDA / DailyMed). For work in aqueous systems this is a substantial advantage over the free base.

Supplied as a powder, purity ≥98%, CAS 35604-67-2.