-2β-Carbomethoxy-3β-(4-ethylphenyl)tropane (RTI-83) is a phenyltropane

Phenyltropane

Phenyltropanes were originally developed to reduce cocaine addiction and dependency. In general these compounds act as inhibitors of the plasmalemmal monoamine reuptake transporters. Although RTI holds a strong position in this field, they are not the only researchers that have prepared these...

 derivative which represents a rare example of an SDRI or serotonin-dopamine reuptake inhibitor, a drug which inhibits the reuptake

Reuptake

Reuptake, or re-uptake, is the reabsorption of a neurotransmitter by a neurotransmitter transporter of a pre-synaptic neuron after it has performed its function of transmitting a neural impulse....

 of the neurotransmitter

Neurotransmitter

Neurotransmitters are endogenous chemicals that transmit signals from a neuron to a target cell across a synapse. Neurotransmitters are packaged into synaptic vesicles clustered beneath the membrane on the presynaptic side of a synapse, and are released into the synaptic cleft, where they bind to...

s serotonin

Serotonin

Serotonin or 5-hydroxytryptamine is a monoamine neurotransmitter. Biochemically derived from tryptophan, serotonin is primarily found in the gastrointestinal tract, platelets, and in the central nervous system of animals including humans...

 and dopamine

Dopamine

Dopamine is a catecholamine neurotransmitter present in a wide variety of animals, including both vertebrates and invertebrates. In the brain, this substituted phenethylamine functions as a neurotransmitter, activating the five known types of dopamine receptors—D1, D2, D3, D4, and D5—and their...

, while having little or no effect on the reuptake of the related neurotransmitter noradrenaline. With a binding affinity (K_i) of 55 nM at DAT

Dopamine transporter

The dopamine transporter is a membrane-spanning protein that pumps the neurotransmitter dopamine out of the synapse back into cytosol, from which other transporters sequester DA and NE into vesicles for later storage and release...

 and 28.4 nM at SERT

Serotonin transporter

The serotonin transporter is a monoamine transporter protein.This protein is an integral membrane protein that transports the neurotransmitter serotonin from synaptic spaces into presynaptic neurons. This transport of serotonin by the SERT protein terminates the action of serotonin and recycles it...

 but only 4030 nM at NET, RTI-83 has reasonable selectivity for DAT/SERT over NET, but further research has shown that by extending the ethyl chain even better selectivity can be achieved, with the 4-(cis-propenyl) analogue having K_i values of 15 nM at DAT and 7.1 nM at SERT, vs 28,000 nM at NET.
Such drugs are speculated to be useful as potential antidepressant

Antidepressant

An antidepressant is a psychiatric medication used to alleviate mood disorders, such as major depression and dysthymia and anxiety disorders such as social anxiety disorder. According to Gelder, Mayou &*Geddes people with a depressive illness will experience a therapeutic effect to their mood;...

s, but few examples have been reported in the literature as yet. However while RTI-83 has been used for binding studies to model the monoamine transporter

Monoamine transporter

Monoamine transporters are protein structures that function as integral plasma membrane transporters to regulate concentrations of extracellular monoamine neurotransmitters. Three major classes of MATs are responsible for the reuptake of their associated amine neurotransmitters...

proteins, its pharmacology in vivo has not been studied in detail.