Synthesis and biological evaluation of the major metabolite of atomoxetine: elucidation of a partial κ-opioid agonist effect

The major human metabolite of atomoxetine (4-hydroxyatomoxetine) was tested against a panel of receptors and enzymes, and was found to interact with the μ, δ, and κ-opioid receptors based upon studies involving both binding and functional assays. 4-Hydroxyatomoxetine was determined to be a partial agonist of the κ-opioid receptor.