25B-NBOMe
25B-NBOMe, also known as NBOMe-2C-B and Cimbi-36, is a psychedelic drug of the 25-NB family derived from 2C-B. It acts as a potent full agonist for the 5HT2A receptor. Duration of effects lasts about 3 to 10hours, although the parent compound is rapidly cleared from the blood when used in the radiolabeled form in tracer doses. Recently, Custodio et al. evaluated the potential involvement of dysregulated dopaminergic system, neuroadaptation, and brain wave changes which may contribute to the rewarding and reinforcing properties of 25B-NBOMe in rodents.
The carbon-11 labeled version of this compound was synthesized and validated as a radioactive tracer for positron emission tomography in Copenhagen. As a 5-HT2A receptor agonist PET radioligand, Cimbi-36 was hypothesized to provide a more functional marker of these receptors. Also, Cimbi-36 is investigated as a potential marker of serotonin release and thus could serve as an indicator of serotonin levels in vivo. Cimbi-36 is now undergoing clinical trials as a PET-ligand in humans.
25B-NBOMe was first described in the scientific literature by Ralf Heim and colleagues at the Free University of Berlin by 1999.
Use and effects
The dose range of 25B-NBOMe has been given as 50 to 700μg sublingually, with a typical dose estimate of 400μg. Doses over 800μg are said to be very strong. Its onset sublingually is said to be 15minutes to 2hours and to be longer than that of LSD.Pharmacology
Pharmacodynamics
25B-NBOMe is a selective serotonin 5-HT2 receptor agonist. It showed roughly the same affinity for the serotonin 5-HT2A, 5-HT2B, and 5-HT2C receptors in one study. However, in another study, it showed 12- to 20-fold selectivity for the serotonin 5-HT2A receptor over the serotonin 5-HT2B and 5-HT2C receptors. The drug is highly selective for the serotonin 5-HT2 receptors over a variety of other serotonin receptors, as well as over various other monoamine receptors and over the monoamine transporters. However, 25B-NBOMe is a low-potency partial agonist of the rat and mouse trace amine-associated receptor 1 but is inactive at the human TAAR1.25B-NBOMe has been found to increase levels of glutamate, serotonin, dopamine, and acetylcholine in the frontal cortex, striatum, and nucleus accumbens in rats. Other serotonergic psychedelics like LSD and DOI have also been found to increase glutamate levels in the frontal cortex in rodents, and this effect can be blocked by the serotonin 5-HT2A receptor antagonist volinanserin. 25B-NBOMe shows an inverted U-shaped dose–response curve in terms of neurotransmitter elevations in multiple brain areas. This may be due to an inhibitory effect of serotonin 5-HT2C receptors at higher doses. 25B-NBOMe produces the head-twitch response, a behavioral proxy of psychedelic effects, in rodents, and this effect shows an inverted U-shaped dose–response curve similarly to its influences on neurotransmitter levels. The head twitches and hallucinogenic effects of 25B-NBOMe may be due to increased cortical glutamate release secondary to serotonin 5-HT2A receptor activation. The effects of 25B-NBOMe on levels of other neurotransmitters, such as accumbal dopamine concentrations, may also be mediated by activation of serotonin 5-HT2A receptors and glutamate elevation. It has been suggested that the serotonin elevations with 25B-NBOMe may be involved in its production of serotonin syndrome in humans.
Unlike many other serotonergic psychedelics, 25B-NBOMe has been found to produce reinforcing effects in rodents, including conditioned place preference and self-administration, and hence may have misuse potential. Accordingly, 25B-NBOMe robustly increased dopamine levels in the nucleus accumbens in rodents similarly to but a lesser extent than methamphetamine, and its reinforcing effects could be blocked by the dopamine receptor antagonists SCH-23390 and haloperidol. Serotonin 5-HT2A receptor activation is known to increase dopamine release in the mesolimbic pathway. However, the reinforcing effects of 25B-NBOMe were not blocked by the selective serotonin 5-HT2A receptor antagonist ketanserin. Similarly to 25B-NBOMe, 25N-NBOMe has also shown reinforcing effects in rodents. More research is needed to elucidate how 25B-NBOMe and other NBOMe drugs produce reinforcing effects in animals.
25B-NBOMe has been found to decrease locomotor activity in rodents.
25B-NBOMe has been found to produce neurotoxicity in rodents.