Serotonin–norepinephrine reuptake inhibitors (SNRIs) are a class of antidepressant drugs used to treat major depressive disorder (MDD), anxiety disorders, obsessive–compulsive disorder (OCD), social phobia, attention-deficit hyperactivity disorder (ADHD), chronic neuropathic pain, fibromyalgia syndrome (FMS), and menopausal symptoms. SNRIs are monoamine reuptake inhibitors; specifically, they inhibit the reuptake of serotonin and norepinephrine. These neurotransmitters are thought to play an important role in mood regulation. SNRIs can be contrasted with the more widely used selective serotonin reuptake inhibitors (SSRIs), which act upon serotonin only.
Dextrorphan (DXO) is a psychoactive drug of the morphinan class which acts as an antitussive or cough suppressant and dissociative hallucinogen. It is the dextrorotatory enantiomer of racemorphan; the levorotatory enantiomer is levorphanol. Dextrorphan is produced by O-demethylation of dextromethorphan by CYP2D6. Dextrorphan is an NMDA antagonist and contributes to the psychoactive effects of dextromethorphan.
Trimipramine, sold under the brand name Surmontil among others, is a tricyclic antidepressant (TCA) which is used to treat depression. It has also been used for its sedative, anxiolytic, and weak antipsychotic effects in the treatment of insomnia, anxiety disorders, and psychosis, respectively. The drug is described as an atypical or "second-generation" TCA because, unlike other TCAs, it seems to be a fairly weak monoamine reuptake inhibitor. Similarly to other TCAs however, trimipramine does have antihistamine, antiserotonergic, antiadrenergic, antidopaminergic, and anticholinergic activities.
(+)-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.
Desmetramadol (INN), also known as O-desmethyltramadol (O-DSMT), is an opioid analgesic and the main active metabolite of tramadol. Tramadol is demethylated by the liver enzyme CYP2D6 in the same way as codeine, and so similarly to the variation in effects seen with codeine, individuals who have a less active form of CYP2D6 will tend to get reduced analgesic effects from tramadol. This also results in a ceiling effect which limits tramadol's range of therapeutic benefits to the treatment of moderate pain.
Ethylphenidate (EPH), also known as Baxtercaine in the United Kingdom is a psychostimulant and a close analog of methylphenidate.
Nisoxetine, originally synthesized in the Lilly research laboratories during the early 1970s, is a potent and selective inhibitor for the reuptake of norepinephrine (noradrenaline) into synapses. It currently has no clinical applications in humans, although it was originally researched as an antidepressant. Nisoxetine is now widely used in scientific research as a standard selective norepinephrine reuptake inhibitor. It has been used to research obesity and energy balance, and exerts some local analgesia effects.
A reuptake inhibitor (RI) is a type of drug known as a reuptake modulator 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.
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.
Oxaprotiline, also known as hydroxymaprotiline, is a norepinephrine reuptake inhibitor of the tetracyclic antidepressant (TeCA) family that is related to maprotiline. Though investigated as an antidepressant, it was never marketed.
DOV-102,677 is a psychoactive drug being developed by Merck and is currently in clinical trials. It is a triple reuptake inhibitor (TRI), or serotonin-norepinephrine-dopamine reuptake inhibitor (SNDRI). It is the (−)-enantiomer of DOV-216,303, and its (+)-enantiomer is DOV-21,947 (amitifadine).
JNJ-7925476 is a triple reuptake inhibitor antidepressant discovered by Johnson & Johnson, but never marketed.
Amitifadine is a serotonin–norepinephrine–dopamine reuptake inhibitor (SNDRI) or so-called triple reuptake inhibitor (TRI) which is or was being developed by Euthymics Bioscience It was under development for the treatment of major depressive disorder, but in May 2013, it was reported that the drug failed to show superior efficacy to placebo in a phase IIb/IIIa clinical trial. It was suggested that this may have been due to the drug being underdosed. In September 2017, development of amitifadine for the treatment of major depressive disorder was finally officially discontinued. As of September 2017, it is still listed as being under development for the treatment of alcoholism and smoking withdrawal.
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.
Pseudophenmetrazine is a psychostimulant compound of the morpholine class. It is the N-demethylated and cis-configured analogue of phendimetrazine as well as the cis-configured stereoisomer of phenmetrazine. In addition, along with phenmetrazine, it is believed to be one of the active metabolites of phendimetrazine, which itself is inactive and behaves merely as a prodrug. Relative to phenmetrazine, pseudophenmetrazine is of fairly low potency, acting as a modest releasing agent of norepinephrine (EC50 = 514 nM), while its (+)-enantiomer is a weak releaser of dopamine (EC50 = 1,457 nM) whereas its (−)-enantiomer is a weak reuptake inhibitor of dopamine (Ki = 2,691 nM); together as a racemic mixture with the two enantiomers combined, pseudophenmetrazine behaves overall more as a dopamine reuptake inhibitor (Ki = 2,630 nM), possibly due to the (+)-enantiomer blocking the uptake of the (−)-enantiomer into dopaminergic neurons and thus preventing it from inducing dopamine release. Neither enantiomer has any significant effect on serotonin reuptake or release (both Ki = >10,000 nM and EC50 = >10,000 nM, respectively).
Selective serotonin reuptake inhibitors, or serotonin-specific re-uptake inhibitor (SSRIs), are a class of chemical compounds that have contributed to the major advances as antidepressants where they have revolutionised the treatment of depression and other psychiatric disorders. The SSRIs are therapeutically useful in the treatment of panic disorder (PD), posttraumatic stress disorder (PTSD), social anxiety disorder, obsessive-compulsive disorder (OCD), premenstrual dysphoric disorder (PMDD), and anorexia. There is also clinical evidence of SSRIs efficiency in the treatment of the negative symptoms of schizophrenia and their ability to prevent cardiovascular diseases.
Selective norepinephrine reuptake inhibitors (sNRIs) are a class of drugs that have been marketed as antidepressants and are used for various mental disorders, mainly depression and attention-deficit hyperactivity disorder (ADHD). The norepinephrine transporter (NET) serves as the fundamental mechanism for the inactivation of noradrenergic signaling because of the NET termination in the reuptake of norepinephrine (NE). The selectivity and mechanism of action for the NRI drugs remain mostly unresolved and, to date, only a limited number of NRI-selective inhibitors are available. The first commercially available selective NRI was the drug reboxetine (Edronax), developed as a first-line therapy for major depressive disorder. Atomoxetine (Strattera) is another potent and selective NRI which is also effective and well tolerated for the treatment of ADHD in adults; it may also be a new treatment option for adults with ADHD, particularly for those patients at risk of substance abuse.
Didesmethylsibutramine (BTS-54524) is an active metabolite of the anorectic drug sibutramine that has been identified as an adulterant in weight loss supplements. Data on the activity of didesmethylsibutramine in humans is limited, although a case of psychosis associated with didesmethylsibutramine use was reported in 2019.
