R-(-)-O-Desmethyl Venlafaxine is a metabolite of R-Venlafaxine , a selective serotonin noradrenaline reuptake inhibitor. This bicyclic molecule facilitates neurotransmission by preventing presynaptic reuptake, resulting in a higher concentration of neurotransmitters located within the synapse. It is known that the neurotransmitters most effected by this inhibitor are norepinephrine and serotonin, which weakly suppress dopamine at high concentrations. Furthermore, studies show that R-(-)-O-Desmethyl Venlafaxine can be seperated from Venlafaxine using LC-MS/MS in rat plasma.