Dopamine reuptake inhibitor | |
---|---|
Drug class | |
Class identifiers | |
Use | Major depressive disorder, attention-deficit hyperactivity disorder, narcolepsy |
Biological target | Dopamine transporter |
Legal status | |
In Wikidata |
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. [1]
DRIs are used in the treatment of attention-deficit hyperactivity disorder (ADHD) and narcolepsy for their psychostimulant effects, and in the treatment of obesity and binge eating disorder for their appetite suppressant effects. They are sometimes used as antidepressants in the treatment of mood disorders, but their use as antidepressants is limited given that strong DRIs have a high abuse potential and legal restrictions on their use. Lack of dopamine reuptake and the increase in extracellular levels of dopamine have been linked to increased susceptibility to addictive behavior given increase in dopaminergic neurotransmission.[ citation needed ] The dopaminergic pathways are considered to be strong reward centers.[ citation not found ] Many DRIs such as cocaine are drugs of abuse due to the rewarding effects evoked by elevated synaptic concentrations of dopamine in the brain.
Until the 1950s, dopamine was thought to only contribute to the biosynthesis of norepinephrine and epinephrine. It was not until dopamine was found in the brain in similar levels as norepinephrine that the possibility was considered that its biological role might be other than the synthesis of the catecholamines. [2]
The following drugs have DRI action and have been or are used clinically specifically for this property: amineptine, dexmethylphenidate, difemetorex, fencamfamine, lefetamine, levophacetoperane, medifoxamine, mesocarb, methylphenidate, nomifensine, pipradrol, prolintane, and pyrovalerone.
The following drugs are or have been used clinically and possess only weak DRI action, which may or may not be clinically-relevant: adrafinil, armodafinil, bupropion, mazindol, modafinil, nefazodone, sertraline, and sibutramine.
The following drugs are or have been clinically used but only coincidentally have DRI properties: benzatropine, diphenylpyraline, etybenzatropine, ketamine, nefopam, pethidine (meperidine), and tripelennamine.
The following are a selection of some particularly notably abused DRIs: cocaine, ketamine, MDPV, naphyrone, and phencyclidine (PCP). Amphetamines, including amphetamine, methamphetamine, MDMA, cathinone, methcathinone, mephedrone, and methylone, are all DRIs as well, but are distinct in that they also behave, potentially more potently, as dopamine releasing agents (DRAs) (due to Yerkes–Dodson's law, 'more potently stimulated' may not equal more optimally functionally stimulated). There are very distinct differences in the mode of action between dopamine releasers/substrates & dopamine re-uptake inhibitors; the former are functionally entropy-driven (i.e., relating to hydrophobicity) and the latter are enthalpy-driven (i.e., relating conformational change). [3] [4] Reuptake inhibitors such as cocaine induce hyperpolarization of cloned human DAT upon oocytes that are naturally found on neurons, whereas releasing agents induce de-polarization of the neuron membrane.[ dubious – discuss ] [5] [6]
The wakefulness-promoting agent modafinil and its analogues (e.g., adrafinil, armodafinil) have been approved to treat narcolepsy and shift work sleep disorder. [7] These act as weak (micromolar) DRIs, [8] but this effect does not correlate with wakefulness-promoting effects, suggesting the effect is too weak to be of clinical significance. The conclusion is these drugs promote wakefulness via some other mechanism. [9] [ disputed – discuss ]
DRIs have been explored as potential antiaddictive agents in the context of replacement therapy strategies, analogous to nicotine replacement for treating tobacco addiction and methadone replacement in the case of opioid addiction. DRIs have been explored as treatment for cocaine addiction, and have shown to alleviate cravings and self-administration. [10]
Monoamine reuptake inhibitors, including DRIs, have shown effectiveness as therapy for excessive food intake and appetite control for obese patients. Though such pharmacotherapy is still available, the majority of stimulant anorectics marketed for this purpose have been withdrawn or discontinued due to adverse side effects such as hypertension, valvulopathy, and drug dependence. [11]
Only DRIs which are selective for the DAT over the other monoamine transporters (MATs) are listed below. For a list of DRIs that act at multiple MATs, see other monoamine reuptake inhibitor pages such as NDRI and SNDRI.[ disputed – discuss ]
Methylphenidate, sold under the brand names Ritalin and Concerta among others, is a mild
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 norepinephrine reuptake inhibitor or noradrenaline reuptake inhibitor or adrenergic reuptake inhibitor (ARI), is a type of drug that acts as a reuptake inhibitor for the neurotransmitters norepinephrine (noradrenaline) and epinephrine (adrenaline) by blocking the action of the norepinephrine transporter (NET). This in turn leads to increased extracellular concentrations of norepinephrine and epinephrine and therefore can increase adrenergic neurotransmission.
Dopaminergic means "related to dopamine" (literally, "working on dopamine"), dopamine being a common neurotransmitter. Dopaminergic substances or actions increase dopamine-related activity in the brain. Dopaminergic brain pathways facilitate dopamine-related activity. For example, certain proteins such as the dopamine transporter (DAT), vesicular monoamine transporter 2 (VMAT2), and dopamine receptors can be classified as dopaminergic, and neurons that synthesize or contain dopamine and synapses with dopamine receptors in them may also be labeled as dopaminergic. Enzymes that regulate the biosynthesis or metabolism of dopamine such as aromatic L-amino acid decarboxylase or DOPA decarboxylase, monoamine oxidase (MAO), and catechol O-methyl transferase (COMT) may be referred to as dopaminergic as well. Also, any endogenous or exogenous chemical substance that acts to affect dopamine receptors or dopamine release through indirect actions (for example, on neurons that synapse onto neurons that release dopamine or express dopamine receptors) can also be said to have dopaminergic effects, two prominent examples being opioids, which enhance dopamine release indirectly in the reward pathways, and some substituted amphetamines, which enhance dopamine release directly by binding to and inhibiting VMAT2.
The norepinephrine transporter (NET), also known as noradrenaline transporter (NAT), is a protein that in humans is encoded by the solute carrier family 6 member 2 (SLC6A2) gene.
Armodafinil (trade name Nuvigil) is the enantiopure compound of the eugeroic modafinil (Provigil). It consists of only the (R)-(−)-enantiomer of the racemic modafinil. Armodafinil is produced by the pharmaceutical company Cephalon Inc. and was approved by the U.S. Food and Drug Administration (FDA) in June 2007. In 2016, the FDA granted Mylan rights for the first generic version of Cephalon's Nuvigil to be marketed in the U.S.
Phenyltropanes (PTs) were originally developed to reduce cocaine addiction and dependency. In general these compounds act as inhibitors of the plasmalemmal monoamine reuptake transporters. This research has spanned beyond the last couple decades, and has picked up its pace in recent times, creating numerous phenyltropanes as research into cocaine analogues garners interest to treat addiction.
(+)-CPCA is a stimulant drug similar in structure to pethidine and to RTI-31, but nocaine is lacking 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.
Ethylphenidate (EPH) is a psychostimulant and a close analog of methylphenidate.
Benzofuranylpropylaminopentane is a drug with an unusual monoamine-release potentiating property, in addition to classical monoamine reuptake inhibition.
A dopamine releasing agent (DRA) is a type of drug which induces the release of dopamine in the body and/or brain. No selective DRAs are currently known. Many releasing agents of both dopamine and norepinephrine and of serotonin, norepinephrine, and dopamine are known, however. Serotonin–dopamine releasing agents are much rarer and are not selective for monoamine release. Examples of NDRAs include amphetamine and methamphetamine, and an example of an SNDRA is MDMA. The most selective dopamine releaser is 4-methylaminorex, but it also has considerable activity as a norepinephrine releaser. These drugs are frequently used for recreational purposes and encountered as drugs of abuse.
RTI(-4229)-113 is a stimulant drug which acts as a potent and fully selective dopamine reuptake inhibitor (DRI). It has been suggested as a possible substitute drug for the treatment of cocaine addiction. "RTI-113 has properties that make it an ideal medication for cocaine abusers, such as an equivalent efficacy, a higher potency, and a longer duration of action as compared to cocaine." Replacing the methyl ester in RTI-31 with a phenyl ester makes the resultant RTI-113 fully DAT specific. RTI-113 is a particularly relevant phenyltropane cocaine analog that has been tested on squirrel monkeys. RTI-113 has also been tested against cocaine in self-administration studies for DAT occupancy by PET on awake rhesus monkeys. The efficacy of cocaine analogs to elicit self-administration is closely related to the rate at which they are administered. Slower onset of action analogs are less likely to function as positive reinforcers than analogues that have a faster rate of onset.
RTI(-4229)-112 is a synthetic stimulant drug from the phenyltropane family. In contrast to RTI-113, which is DAT selective, RTI-112 is a nonselective triple reuptake inhibitor.
Eugeroics, also known as wakefulness-promoting agents and wakefulness-promoting drugs, are a class of drugs that promote wakefulness and alertness. They are medically indicated for the treatment of certain sleep disorders including excessive daytime sleepiness (EDS) in narcolepsy or obstructive sleep apnea (OSA). Eugeroics are also often prescribed off-label for the treatment of EDS in idiopathic hypersomnia. In contrast to classical psychostimulants, such as methylphenidate and amphetamine, which are also used in the treatment of these disorders, eugeroics typically do not produce marked euphoria, and, consequently, have a lower addictive potential.
A norepinephrine–dopamine reuptake inhibitor (NDRI) is a drug used for the treatment of clinical depression, attention deficit hyperactivity disorder (ADHD), narcolepsy, and the management of Parkinson's disease. The drug acts as a reuptake inhibitor for the neurotransmitters norepinephrine and dopamine by blocking the action of the norepinephrine transporter (NET) and the dopamine transporter (DAT), respectively. This in turn leads to increased extracellular concentrations of both norepinephrine and dopamine and, therefore, an increase in adrenergic and dopaminergic neurotransmission.
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.
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.