(R)-Duloxetine, with CAS number 116539-60-7, is the (R)-enantiomer of the widely used antidepressant drug duloxetine. It is a chiral molecule structurally characterized as a thiophene derivative containing a naphthalene ring and an amine functional group. Duloxetine itself is a potent and balanced dual reuptake inhibitor of serotonin (5-HT) and norepinephrine (NE). It is primarily indicated for the treatment of major depressive disorder (MDD), generalized anxiety disorder (GAD), neuropathic pain associated with diabetic peripheral neuropathy, fibromyalgia, and chronic musculoskeletal pain. The (R)-enantiomer is studied to understand its specific pharmacological profile and potential differences in activity compared to the active (S)-enantiomer or the racemic mixture used clinically. The commercial drug product, Cymbalta, contains the (S)-enantiomer as the therapeutically active ingredient. (R)-Duloxetine serves as a crucial reference standard and an important intermediate in the stereoselective synthesis and analytical characterization of the active pharmaceutical ingredient (API).