4-Hydroxyatomoxetine is an active metabolite of Atomoxetine. 4-Hydroxyatomoxetine is metabolized by the enzyme cytochrome P450 2D6 (CYP2D6). Atomoxetine hydrochloride is a potent and selective noradrenalin re-uptake inhibitor (Ki values are 5 nM, 77 nM and 1451 nM for inhibition of radioligand binding to human NET, SERT and DAT respectively)[1][2].
[1]. JT Brown, Single Dose Pharmacokinetics of Atomoxetine in Children. [2]. Bymaster FP, Katner JS, Nelson DL et al. Atomoxetine increases extracellular levels of norepinephrine and dopamine in prefrontal cortex of rat: a potential mechanism for efficacy in attention deficit/hyperactivity disorder. Neuropsychopharmacology. 2002 Nov;27(5):699-711.