<qa>  What is the serotonin-norepinephrine reupThe present study will aim to evaluate the efficacy of milnacipran in the treatment of pain due to osteoarthritis OA, that is, to determine whether milnacipran provides superior efficacy to placebo in patients with OA. Milnacipran is a serotonin-norepinephrine reuptake inhibitor SNRI that is currently approved in the United States in the treatment of major depressive disorder and fibromyalgia. There is increased evidence to suggest that SNRIs may be effective in the treatment of chronic pain conditions, such as OA. 