Radafaxine

Radafaxine is drug candidate designated GW-353,162 by GlaxoSmithKline, investigated for treatment of restless leg syndrome and as an NDRI antidepressant. GlaxoSmithKline was targeting Radafaxine for regulatory filing in 2007, but development was discontinued in 2006 due to "poor test results".

Chemistry
It is a potent metabolite of bupropion, the compound in GlaxoSmithKline's Wellbutrin. More specifically, "6-hydroxybupropion" is an analogue of bupropion, and radafaxine is an isolated isomer of 6-hydroxybupropion.

Therefore, radafaxine builds on at least some of the properties of bupropion in humans.

Effects
In various clinical trials, radafaxine has been studied as a treatment for clinical depression, obesity, and neuropathic pain. Radafaxine is described as a norepinephrine-dopamine reuptake inhibitor (NDRI).

Unlike bupropion (which has a slightly higher effect on dopamine reuptake), radafaxine seems to have a higher potency on norepinephrine. This, according to GlaxoSmithKline, may account for the increased effect of radafaxine on pain and fatigue.

Radafaxine has about 70% of bupropion's efficacy in blocking dopamine reuptake, and 392% of efficacy in blocking norepinephrine reuptake.

At least one study suggests that radafaxine has a low abuse potential similar to bupropion.