Venlafaxine hydrochloride. Molecular model of the drug venlafaxine hydrochloride (C17.H27.N.O2?H.Cl). This antidepressant of the serotonin-norepinephrine reuptake inhibitor (SNRI) class is sold under the brand name Effexor XR. It increases the concentrations of the neurotransmitters serotonin and norepinephrine in the body and the brain. Atoms are represented as spheres and are colour-coded: carbon (grey), hydrogen (white), nitrogen (blue), oxygen (red) and chlorine (green).