Assessment of the acute effects of 2C-B vs psilocybin on subjective experience, mood and cognition

This double-blind study (n=22) compares the effect of 2C-B (20mg) and psilocybin (15mg). It finds that 2C-B elicited alterations in consciousness of a psychedelic nature but with a shorter duration of self-reported effects than psilocybin. The study categorised 2C-B (at least at that dose) as a subjectively “lighter” psychedelic.

Abstract of Assessment of the acute effects of 2C-B vs psilocybin

“2,5-dimethoxy-4-bromophenethylamine (2C-B) is a hallucinogenic phenethylamine derived from mescaline. Observational and preclinical data have suggested it to be capable of producing both subjective and emotional effects on par with other classical psychedelics and entactogens. Whereas it is the most prevalently used novel serotonergic hallucinogen to date, it’s acute effects and distinctions from classical progenitors have yet to be characterised in a controlled study. We assessed for the first time the immediate acute subjective, cognitive, and cardiovascular effects of 2C-B (20 mg) in comparison to psilocybin (15mg) and placebo in a within-subjects, double-blind, placebo-controlled study of 22 healthy psychedelic-experienced participants. 2C-B elicited alterations of waking consciousness of a psychedelic nature, with dysphoria, subjective impairment, auditory alterations, and affective elements of ego dissolution largest under psilocybin. Participants demonstrated equivalent psychomotor slowing and spatial memory impairments under either compound compared to placebo, as indexed by the Digit Symbol Substitution Test (DSST), Tower of London (TOL) and Spatial Memory Task (SMT). Neither compound produced empathogenic effects on the Multifaceted Empathy Test (MET). 2C-B induced transient pressor effects to a similar degree as psilocybin. The duration of self-reported effects of 2C-B was shorter than that of psilocybin, largely resolving within 6 hours. Present findings support the categorisation of 2C-B as a subjectively “lighter” psychedelic. Tailored dose-effect studies are needed to discern the pharmacokinetic dependency of 2C-B’s experiential overlaps.”

Authors: Pablo Mallaroni, Natasha L. Mason, Johannes T. Reckweg, Riccardo Paci, Sabrina Ritscher, Stefan W. Toennes, Eef L. Theunissen, Kim P. C. Kuypers & Johannes G. Ramaekers

Summary of Assessment of the acute effects of 2C-B vs psilocybin

Classical psychedelics such as psilocybin are safe and effective treatments for neuropsychiatric disorders such as major depressive disorder. They act via partial serotonin (5-HT) receptor agonism.

While 5-HT2A receptor agonism has been suggested to play a central role in mediating alterations to waking consciousness, evidence suggests that an entourage of receptor subclasses may also explain experiential differences.