Norepinephrine reuptake inhibitors are drugs that block the reuptake for the norepinephrine and epinephrine neurotransmitters.
 
 
Recommended Resources
Mayo Clinic: Serotonin and Norepinephrine Reuptake Inhibitors
Explains how SNRIs work, what they are side effects, and details about serotonin syndrome.
http://www.mayoclinic.com/health/antidepressants/MH00067
Selective Norepinephrine Reuptake Inhibitors
About.com's details about these antidepressants includes definitions of SNRI and SSNRI, information about Cymbalta and Effexor, and Serzone medication profile.
http://bipolar.about.com/od/snri/Selective_Norepinephrine_Reuptake_Inhibitors.htm
Serotonin-Norepinephrine Reuptake Inhibitor
Contains a rather lengthy article about SNRIs and how they work, as well as some of the common side effects.
http://www.healthyplace.com/depression/antidepressants/snri-serotonin-norepinephrine-reuptake-inhibitors/menu-id-68/