However, some reports suggest that SSRIs (which are also sometimes used for certain neuropathic pain conditionsthough with somewhat questionable efficacy) have even fewer side effects than SNRIs.4,5How Do These Drugs Work 200?SNRIs work by blocking the reabsorption (or reuptake) of serotonin and norepinephrine back into the nerve cells that released them, which increases the levels of active neurotransmitters in the brain.6SNRIs block the reabsorption (or reuptake) of serotonin and norepinephrine back into the nerve cells that released them. Both of these neurotransmitters are associated with distinct brain structures and functions and impact various processes such as mood and energy in somewhat different ways. Increasing levels of them in the brain may help improve mood and emotion. Examples of SNRIs include:6Venlafaxine (Effexor).Duloxetine (Cymbalta).Desvenlafaxine (Pristiq, Khedezla).Milnacipran (Savella).Levomilnacipran (Fetzima) prix. EffexorEffexor was the first SNRI marketed in the United States and the first to be approved by the Food and Drug Administration (FDA). It is structurally different from several other SNRIs with its bicyclic, or two-ring, structure. Effexor and its time-released formulation Effexor XR are approved for the treatment of major depression, generalized anxiety disorder, panic disorder, and social phobia.9Effexor has disproportionate reuptake inhibition effects. It is 30 times more selective for inhibiting the reuptake of serotonin than it is for norepinephrine venta.