A reuptake inhibitor (RI), also known as a transporter blocker, is a drug that inhibits the transporter-mediated reuptake of a neurotransmitter from the synapse into the pre-synaptic neuron, leading to an increase in the extracellular concentrations of the neurotransmitter and therefore an increase in neurotransmission.
Various drugs utilize reuptake inhibition to exert their psychological and physiological effects, including many antidepressants and psychostimulants.
Most known reuptake inhibitors affect the monoamine neurotransmitters: serotonin, norepinephrine (and epinephrine), and dopamine.
However there are also a number of pharmaceuticals and research chemicals that act as reuptake inhibitors for other neurotransmitters such as glutamate, γ-aminobutyric acid (GABA), glycine, adenosine,choline (the precursor of acetylcholine), and the endocannabinoids, among others.