A class of medications (also called selective norepinephrine reuptake inhibitors or norepinephrine specific reuptake inhibitors) that increase levels of the neurotransmitters norepinephrine and epinephrine by blocking the action of the norepinephrine transporter and hence the reuptake of neurotransmitters back into neurons. NRIs may be used in the clinical treatment of attention-deficit/hyperactivity disorder (ADHD) and narcolepsy (e.g., atomoxetine [strattera]) as well as mood disorders such as major depressive disorder (e.g., the tetracyclic agent maprotiline [ludiomil]).