Psychopharmacology is the scientific study of the effects drugs have on mood, sensation, thinking, behavior, judgment and evaluation, and memory. It is distinguished from neuropsychopharmacology, which emphasizes the correlation between drug-induced changes in the functioning of cells in the nervous system and changes in consciousness and behavior.
Monoamine transporters (MATs) are proteins that function as integral plasma-membrane transporters to regulate concentrations of extracellular monoamine neurotransmitters. The three major classes are serotonin transporters (SERTs), dopamine transporters (DATs), and norepinephrine transporters (NETs) and are responsible for the reuptake of their associated amine neurotransmitters. MATs are located just outside the synaptic cleft (peri-synaptically), transporting monoamine transmitter overflow from the synaptic cleft back to the cytoplasm of the pre-synaptic neuron. MAT regulation generally occurs through protein phosphorylation and post-translational modification. Due to their significance in neuronal signaling, MATs are commonly associated with drugs used to treat mental disorders as well as recreational drugs. Compounds targeting MATs range from medications such as the wide variety of tricyclic antidepressants, selective serotonin reuptake inhibitors such as fluoxetine (Prozac) to stimulant medications such as methylphenidate (Ritalin) and amphetamine in its many forms and derivatives methamphetamine (Desoxyn) and lisdexamfetamine (Vyvanse). Furthermore, drugs such as MDMA and natural alkaloids such as cocaine exert their effects in part by their interaction with MATs, by blocking the transporters from mopping up dopamine, serotonin, and other neurotransmitters from the synapse.
A dopamine reuptake inhibitor (DRI) is a class of drug which acts as a reuptake inhibitor of the monoamine neurotransmitter dopamine by blocking the action of the dopamine transporter (DAT). Reuptake inhibition is achieved when extracellular dopamine not absorbed by the postsynaptic neuron is blocked from re-entering the presynaptic neuron. This results in increased extracellular concentrations of dopamine and increase in dopaminergic neurotransmission.
Cocaethylene (ethylbenzoylecgonine) is the ethyl ester of benzoylecgonine. It is structurally similar to cocaine, which is the methyl ester of benzoylecgonine. Cocaethylene is formed by the liver when cocaine and ethanol coexist in the blood. In 1885, cocaethylene was first synthesized, and in 1979, cocaethylene's side effects were discovered.
(+)-CPCA is a stimulant drug similar in structure to pethidine and to RTI-31, but nocaine lacks the two-carbon bridge of RTI-31's tropane skeleton. This compound was first developed as a substitute agent for cocaine.
A serotonin–norepinephrine–dopamine reuptake inhibitor (SNDRI), also known as a triple reuptake inhibitor (TRI), is a type of drug that acts as a combined reuptake inhibitor of the monoamine neurotransmitters serotonin, norepinephrine, and dopamine. It does this by concomitantly inhibiting the serotonin transporter (SERT), norepinephrine transporter (NET), and dopamine transporter (DAT), respectively. Inhibition of the reuptake of these neurotransmitters increases their extracellular concentrations and, therefore, results in an increase in serotonergic, adrenergic, and dopaminergic neurotransmission. The naturally-occurring and potent SNDRI cocaine is widely used recreationally and often illegally for the euphoric effects it produces.
Reuptake inhibitors (RIs) are a type of reuptake modulators. It is a drug that inhibits the plasmalemmal transporter-mediated reuptake of a neurotransmitter from the synapse into the pre-synaptic neuron. This leads to an increase in extracellular concentrations of the neurotransmitter and an increase in neurotransmission. Various drugs exert their psychological and physiological effects through reuptake inhibition, including many antidepressants and psychostimulants.
LR-5182 is a stimulant drug which acts as a norepinephrine–dopamine reuptake inhibitor, structurally related to the better known drug fencamfamine. It was developed by the pharmaceutical company Eli Lilly in the 1970s, and researched for potential use as an antidepressant, although never marketed. LR-5182 has two stereoisomers, both of which are active, although one isomer blocks reuptake of only dopamine and noradrenaline, while the other blocks reuptake of serotonin as well.
Dichloropane ((−)-2β-Carbomethoxy-3β-(3,4-dichlorophenyl)tropane, RTI-111, O-401) is a stimulant of the phenyltropane class that acts as a serotonin–norepinephrine–dopamine reuptake inhibitor (SNDRI) with IC50 values of 3.13, 18, and 0.79 nM, respectively. In animal studies, dichloropane had a slower onset and longer duration of action compared to cocaine.
RTI-126 is a phenyltropane derivative which acts as a potent monoamine reuptake inhibitor and stimulant drug, and has been sold as a designer drug. It is around 5 times more potent than cocaine at inhibiting monoamine reuptake in vitro, but is relatively unselective. It binds to all three monoamine transporters, although still with some selectivity for the dopamine transporter. RTI-126 has a fast onset of effects and short duration of action, and its pharmacological profile in animals is among the closest to cocaine itself out of all the drugs in the RTI series. Its main application in scientific research has been in studies investigating the influence of pharmacokinetics on the abuse potential of stimulant drugs, with its rapid entry into the brain thought to be a key factor in producing its high propensity for development of dependence in animals.
RTI(-4229)-336, is a phenyltropane derivative which acts as a potent and selective dopamine reuptake inhibitor and stimulant drug. It binds to the dopamine transporter with around 20x the affinity of cocaine, however it produces relatively mild stimulant effects, with a slow onset and long duration of action. These characteristics make it a potential candidate for treatment of cocaine addiction, as a possible substitute drug analogous to how methadone is used for treating heroin abuse. RTI-336 fully substitutes for cocaine in addicted monkeys and supports self-administration, and significantly reduces rates of cocaine use, especially when combined with SSRIs, and research is ongoing to determine whether it could be a viable substitute drug in human cocaine addicts.
Talopram, also known as phthalapromine, is a selective norepinephrine reuptake inhibitor (NRI) which was researched for the management of depression in the 1960s and 1970s but was never commercialized. Along with talsupram, talopram is structurally related to the selective serotonin reuptake inhibitor (SSRI) citalopram, as well as to melitracen:
In 1971, the company hired Klaus Bøgesø as a medicinal chemist. Over the years Bøgesø turned out to have a Midas touch at the game of drug hunting, creating more molecules that made it to the market than almost any other medicinal chemist in the field. The challenge facing him in 1971 following his recruitment was to produce a selective norepinephrine reuptake inhibitor. Like other companies at the time, Lundbeck had little interest in an SSRI. Bøgesø began from an accident in the laboratory. Trying to create a derivative of their norepinephrine reuptake inhibiting antidepressant melitracen, Lundbeck chemists accidentally produced a new chemical — a phenylphthalene. Against all the odds, just like melitracen, this was also a selective norepinephrine reuptake inhibitor. Two potential antidepressants came out of this — talopram and tasulopram, which were pressed into clinical trials. Both however turned out to be energizing, and in a number of cases there were suicide attempts. The fact that there were suicide attempts appeared to confirm another proposal of Paul Kielholz, that activating antidepressants might lead to suicide. Lundbeck's experience suggested that norepinephrine reuptake inhibitors were likely to lead to just this problem. Lundbeck retreated, scared. If norepinephrine reuptake inhibitors were likely to trigger suicide, the greatest hazard of an antidepressant, then Kielholz's view suggested that an SSRI would be less likely to lead to suicide. Bøgesø's job was to see whether the new series of drugs could be converted into a series of SSRIs. Following a lead from Carlsson on how to do this, he converted talopram into citalopram, the most selective serotonin reuptake inhibitor to come to the market.
Tametraline (CP-24,441) is the parent of a series of chemical compounds investigated at Pfizer that eventually led to the development of sertraline (CP-51,974-1).
A dopamine releasing agent (DRA) is a type of drug which induces the release of dopamine in the body and/or brain.
Desmethylsertraline (DMS), also known as norsertraline, is an active metabolite of the antidepressant drug sertraline. Like sertraline, desmethylsertraline acts as a monoamine reuptake inhibitor, and may be responsible for some of its parent's therapeutic benefits; however, the effects of DMS's main activity of increasing serotonin levels via binding to the serotonin transporter appears to be negligible as in vivo testing showed no measurable change in brain activity despite a nearly 20-fold increase in DMS blood levels compared to the EC50 (i.e. the amount required to achieve the desired effect in 50% of the population) of its parent drug sertraline. DMS is significantly less potent relative to sertraline as a serotonin reuptake inhibitor (Ki = 76 nM vs. 3 nM, respectively), but conversely, is more balanced as a monoamine reuptake inhibitor (5-HT (Ki) = 76 nM; NE (Ki) = 420 nM; DA (Ki) = 440 nM), which has the effective result of DMS contrarily behaving as a serotonin-norepinephrine-dopamine reuptake inhibitor (SNDRI), with about 5.5-fold preference for inhibiting serotonin reuptake relative to catecholamine reuptake.
JZ-IV-10 is a piperidine derivative related to cocaine which acts as a highly potent serotonin–norepinephrine–dopamine reuptake inhibitor. The eugeroic modafinil was used as a lead to fuel this compound's discovery.
3,4-dichloromethylphenidate is a potent stimulant drug from the phenidate class closely related to methylphenidate. It acts as a potent serotonin-norepinephrine-dopamine reuptake inhibitor with a long duration of action. It has been sold online as a designer drug.
RTI-83 is a phenyltropane derivative which represents a rare example of an SDRI or serotonin-dopamine reuptake inhibitor, a drug which inhibits the reuptake of the neurotransmitters serotonin and dopamine, while having little or no effect on the reuptake of the related neurotransmitter noradrenaline. With a binding affinity (Ki) of 55 nM at DAT and 28.4 nM at SERT but only 4030 nM at NET, RTI-83 has reasonable selectivity for DAT/SERT over NET
A serotonin–dopamine reuptake inhibitor (SDRI) is a type of drug which acts as a reuptake inhibitor of the monoamine neurotransmitters serotonin and dopamine by blocking the actions of the serotonin transporter (SERT) and dopamine transporter (DAT), respectively. This in turn leads to increased extracellular concentrations of serotonin and dopamine, and, therefore, an increase in serotonergic and dopaminergic neurotransmission.
A monoamine reuptake inhibitor (MRI) is a drug that acts as a reuptake inhibitor of one or more of the three major monoamine neurotransmitters serotonin, norepinephrine, and dopamine by blocking the action of one or more of the respective monoamine transporters (MATs), which include the serotonin transporter (SERT), norepinephrine transporter (NET), and dopamine transporter (DAT). This in turn results in an increase in the synaptic concentrations of one or more of these neurotransmitters and therefore an increase in monoaminergic neurotransmission.
