Atomoxetine is a highly selective and potent inhibitor of the presynaptic norepinephrine transporter, with a likely mechanism of action being an indirect effect on the serotonin and dopamine transporters. Atomoxetine has minimal affinity for other noradrenergic receptors or other neurotransmitter transporters or receptors. Atomoxetine has two major oxidative metabolites, 4-hydroxyatomoxetine and N-desmethylatomoxetine. 4-hydroxyatomoxetine is as potent as atomoxetine as an inhibitor of the norepinephrine transporter, but unlike atomoxetine, this metabolite also has some inhibitory activity on the serotonin transporter.