Clinical data | |
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Other names | IRL-790; IRL790; IPN60170 |
Drug class | Atypical dopamine D2 and D3 receptor antagonist |
Pharmacokinetic data | |
Elimination half-life | 7 hours [1] |
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Chemical and physical data | |
Formula | C12H18FNO3S |
Molar mass | 275.34 g·mol−1 |
3D model (JSmol) | |
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Mesdopetam (INN ; developmental code names IRL-790, IPN60170) is a dopamine D2 and D3 receptor antagonist with preference for the D3 receptor which is under development for the treatment of Parkinson's disease, drug-induced dyskinesia, and psychotic disorders. [2] [3] [4] [5] [6] It has been described by its developers as having "psychomotor stabilizing" properties. [7] [8]
The described intention behind mesdopetam was to develop a novel dopamine D2 and D3 receptor antagonist based on agonist- rather than antagonist-like structural motifs and with agonist-like physicochemical properties (e.g., smaller molecular size, greater hydrophilicity). [3] [9] [6] It was hypothesized that this would result in an antagonist with specific dopamine receptor interactions more similar to those of agonists like dopamine but without any intrinsic activity, in turn resulting in different in vivo effects than conventional dopamine receptor antagonists. [9] [6] Specifically, antidyskinetic and antipsychotic effects with fewer or no motor side effects was sought. [6] There is also extensive preclinical research to suggest that D3 receptor antagonists reduce levodopa-induced dyskinesia without compromising the antiparkinsonian effects of levodopa. [3]
Mesdopetam has 6- to 8-fold preference for the dopamine D3 receptor (Ki = 90 nM) over the dopamine D2 receptor (Ki = 540–750 nM). [4] [6] It displays a paradoxical agonist-like binding mode in spite of its lack of activational efficacy. [3] [9] [6] By antagonizing D3 autoreceptors, D3 receptor antagonists like mesdopetam have been found to disinhibit dopamine release in the prefrontal cortex, ventral tegmental area, and striatum, which might be involved in the possible therapeutic benefits of these agents. [4] [6] The drug is also a ligand of the sigma σ1 receptor (Ki = 870 nM) and has some affinity for certain serotonin receptors including the serotonin 5-HT1A and 5-HT2A receptors. [3] [6] In animals, mesdopetam has no effect on spontaneous locomotor activity at assessed doses but antagonizes levodopa-induced dyskinesia and reduces dextroamphetamine- and dizocilpine-induced locomotor hyperactivity. [6]
Side effects of mesdopetam in clinical trials have been reported to include worsened parkinsonism, headache, fatigue, asthenia, and dissociation. [5] [1]
Mesdopetam was first described in the literature in 2012. [6] [10] As of September 2024, it is in phase 2/3 clinical trials for Parkinson's disease, phase 1 trials for drug-induced dyskinesia, and is in preclinical development for psychotic disorders (specifically Parkinson's disease psychosis). [2] [11] It is also of interest for potential treatment of impulse control disorders. [11] In 2019, mesdopetam received an INN with a novel -"dopetam" suffix supposedly representing a new mechanism of action among dopamine receptor modulators. [12] In 2023, it was reported that mesdopetam failed to meet a primary anti-dyskinetic endpoint in a phase 2b trial. [3] However, indications of efficacy were still seen and a phase 3 trial is being planned. [3] No dopamine D3 receptor antagonists have yet completed development or been approved for the treatment of levodopa-induced dyskinesia. [3]
Amantadine, sold under the brand name Gocovri among others, is a medication used to treat dyskinesia associated with parkinsonism and influenza caused by type A influenzavirus, though its use for the latter is no longer recommended because of widespread drug resistance. It is also used for a variety of other uses. The drug is taken by mouth.
A dopamine antagonist, also known as an anti-dopaminergic and a dopamine receptor antagonist (DRA), is a type of drug which blocks dopamine receptors by receptor antagonism. Most antipsychotics are dopamine antagonists, and as such they have found use in treating schizophrenia, bipolar disorder, and stimulant psychosis. Several other dopamine antagonists are antiemetics used in the treatment of nausea and vomiting.
Dopaminergic means "related to dopamine", a common neurotransmitter. Dopaminergic substances or actions increase dopamine-related activity in the brain.
Ropinirole, sold under the brand name Requip among others, is a medication used to treat Parkinson's disease (PD) and restless legs syndrome (RLS). It is taken by mouth.
Pramipexole, sold under the brand Mirapex among others, is a medication used to treat Parkinson's disease (PD) and restless legs syndrome (RLS). In Parkinson's disease it may be used alone or together with levodopa. It is taken by mouth. Pramipexole is a dopamine agonist of the non-ergoline class.
A dopamine agonist is a compound that activates dopamine receptors. There are two families of dopamine receptors, D1-like and D2-like. They are all G protein-coupled receptors. D1- and D5-receptors belong to the D1-like family and the D2-like family includes D2, D3 and D4 receptors. Dopamine agonists are primarily used in the treatment of the motor symptoms of Parkinson's disease, and to a lesser extent, in hyperprolactinemia and restless legs syndrome. They are also used off-label in the treatment of clinical depression. Impulse control disorders are associated with the use of dopamine agonists for whatever condition.
Lisuride, sold under the brand name Dopergin among others, is a monoaminergic medication of the ergoline class which is used in the treatment of Parkinson's disease, migraine, and high prolactin levels. It is taken by mouth.
Rotigotine, sold under the brand name Neupro among others, is a dopamine agonist of the non-ergoline class of medications indicated for the treatment of Parkinson's disease and restless legs syndrome. It is formulated as a once-daily transdermal patch which provides a slow and constant supply of the drug over the course of 24 hours.
Dihydroergocryptine (DHEC), sold under the brand names Almirid and Cripar among others, is a dopamine agonist of the ergoline group that is used as an antiparkinson agent in the treatment of Parkinson's disease. It is taken by mouth.
Istradefylline, sold under the brand name Nourianz, is a medication used as an add-on treatment to levodopa/carbidopa in adults with Parkinson's disease (PD) experiencing "off" episodes. Istradefylline reduces "off" periods resulting from long-term treatment with the antiparkinson drug levodopa. An "off" episode is a time when a patient's medications are not working well, causing an increase in PD symptoms, such as tremor and difficulty walking.
Levodopa, also known as L-DOPA and sold under many brand names, is a dopaminergic medication which is used in the treatment of Parkinson's disease and certain other conditions like dopamine-responsive dystonia and restless legs syndrome. The drug is usually used and formulated in combination with a peripherally selective aromatic L-amino acid decarboxylase (AAAD) inhibitor like carbidopa or benserazide. Levodopa is taken by mouth, by inhalation, through an intestinal tube, or by administration into fat.
Pimavanserin, sold under the brand name Nuplazid, is an atypical antipsychotic which is approved for the treatment of Parkinson's disease psychosis. Unlike other antipsychotics, pimavanserin is not a dopamine receptor antagonist, but rather is a selective inverse agonist of the serotonin 5-HT2A receptor.
Befiradol is an experimental drug being studied for the treatment of levodopa-induced dyskinesia. It is a potent and selective 5-HT1A receptor full agonist.
Levodopa-induced dyskinesia (LID) is a form of dyskinesia associated with levodopa (l-DOPA), used to treat Parkinson's disease. It often involves hyperkinetic movements, including chorea, dystonia, and athetosis.
Sarizotan (EMD-128,130) is a selective 5-HT1A receptor agonist and D2 receptor antagonist, which has antipsychotic effects, and has also shown efficacy in reducing dyskinesias resulting from long-term anti-Parkinsonian treatment with levodopa.
BP-897 is a drug used in scientific research which acts as a potent selective dopamine D3 receptor partial agonist with an in vitro intrinsic activity of ~0.6 and ~70x greater affinity for D3 over D2 receptors and is suspected to have partial agonist or antagonist activity in vivo. It has mainly been used in the study of treatments for cocaine addiction. A study comparing BP-897 with the potent, antagonistic, and highly D3 selective SB-277,011-A found, "SB 277011-A (1–10 mg/kg) was able to block cue-induced reinstatement of nicotine-seeking, indicating that DRD3 selective antagonism may be an effective approach to prevent relapse for nicotine. In contrast, BP 897 did not block the cue-induced reinstatement of nicotine-seeking or nicotine-taking under the FR5 schedule."
OSU-6162 (PNU-96391) is a compound which acts as a partial agonist at both dopamine D2 receptors and 5-HT2A receptors. It acts as a dopamine stabilizer in a similar manner to the closely related drug pridopidine, and has antipsychotic, anti-addictive and anti-Parkinsonian effects in animal studies. Both enantiomers show similar activity but with different ratios of effects, with the (S) enantiomer (–)-OSU-6162 that is more commonly used in research, having higher binding affinity to D2 but is a weaker partial agonist at 5-HT2A, while the (R) enantiomer (+)-OSU-6162 has higher efficacy at 5-HT2A but lower D2 affinity.
Peripherally selective drugs have their primary mechanism of action outside of the central nervous system (CNS), usually because they are excluded from the CNS by the blood–brain barrier. By being excluded from the CNS, drugs may act on the rest of the body without producing side-effects related to their effects on the brain or spinal cord. For example, most opioids cause sedation when given at a sufficiently high dose, but peripherally selective opioids can act on the rest of the body without entering the brain and are less likely to cause sedation. These peripherally selective opioids can be used as antidiarrheals, for instance loperamide (Imodium).
GSK-598809 is a selective dopamine D3 receptor antagonist that is or was under development for the treatment of substance-related disorders, smoking withdrawal, and eating disorders like binge eating disorder.
Pirepemat is a drug which is under development for the prevention of falls in people with Parkinson's disease and Parkinson's disease dementia. It has been referred to as a "nootrope".