A norepinephrine releasing agent (NRA) is a catecholaminergic type of drug which induces the release of norepinephrine and epinephrine from the pre-synaptic neuron into the synapse. This in turn leads to increased extracellular concentrations of norepinephrine and epinephrine therefore an increase in adrenergic neurotransmission. A closely related type of drug is a norepinephrine reuptake inhibitor (NRI). Another class of drugs that stimulates adrenergic activity is the adrenergic agonist class.