25C-NBOMe

25C-NBOMe (2C-C-NBOMe, NBOMe-2C-C, Cimbi-82) is a synthetic N-benzylphenethylamine hallucinogen that acts as a potent agonist of the serotonin 5-HT2A receptor with subnanomolar to low-nanomolar binding affinity (Ki approximately 0.7 to 2.9 nM) and high selectivity over the 5-HT1A receptor (greater than 1000-fold). The compound is derived from the phenethylamine 2C-C (4-chloro-2,5-dimethoxyphenethylamine), first described by Alexander Shulgin, through N-alkylation with 2-methoxybenzaldehyde, a structural modification pioneered by Ralf Heim at the Free University of Berlin in 2003 that increases 5-HT2A receptor affinity approximately 16- to 26-fold relative to the parent 2C compound. 25C-NBOMe was subsequently characterized as a positron emission tomography (PET) radioligand candidate (designated Cimbi-82) by Ettrup and colleagues at the Copenhagen University Hospital for in vivo imaging of the 5-HT2A receptor in its agonist-preferring high-affinity state.

The pharmacological profile of 25C-NBOMe extends beyond 5-HT2A agonism. The compound binds with high affinity to the 5-HT2C receptor (Ki approximately 5.2 to 5.4 nM) and the 5-HT2B receptor (Ki approximately 1.1 nM), and with moderate affinity to alpha-1 adrenergic, histamine H1, sigma-2, and dopamine receptors. This polypharmacology, particularly the combined serotonergic and alpha-1 adrenergic agonism, underlies a toxicological profile that is substantially more hazardous than that of classical serotonergic hallucinogens such as lysergic acid diethylamide (LSD) and psilocybin. 25C-NBOMe produces hallucinogenic effects at submilligram doses (threshold approximately 100 to 250 micrograms sublingually), and the steep dose-response relationship creates a narrow margin between psychoactive and toxic doses, contributing to documented fatalities.

Metabolism proceeds principally through hepatic cytochrome P450-mediated O-demethylation, O-di-demethylation, hydroxylation, and N-dealkylation, with extensive phase II conjugation by glucuronidation and sulfation. The major CYP isoforms implicated are CYP1A2, CYP2B6, CYP2C9, CYP2C19, CYP2D6, and CYP3A4. More than 60 metabolites have been identified in human hepatocyte incubations and in vivo mouse models. The parent compound is not a substrate for monoamine oxidase A or B, distinguishing it pharmacokinetically from the parent 2C series. Duration of psychoactive effect after sublingual administration is approximately 4 to 10 hours, with onset within 15 minutes and peak effect at 30 to 90 minutes.

The compound has no approved medical use in any jurisdiction. It was placed on Schedule I of the United States Controlled Substances Act by the Drug Enforcement Administration in November 2013 under emergency scheduling authority and was permanently scheduled in November 2015. International scheduling includes Class A status in the United Kingdom (2014), Schedule III in Canada, and controlled status in Brazil, Sweden, and multiple other jurisdictions. Clinical case reports and forensic investigations have documented severe intoxications and fatalities attributable to 25C-NBOMe, with toxicological presentations including sympathomimetic crisis, serotonin toxicity, seizures, rhabdomyolysis, metabolic acidosis, acute kidney injury, and cardiovascular collapse. No specific antidote exists; management is supportive. This monograph reviews the chemistry, synthesis, receptor pharmacology, pharmacokinetics, preclinical pharmacology, reported clinical toxicology, forensic analytical considerations, handling, co-exposure interactions, adverse events, and a comparative assessment of five structurally or pharmacologically related hallucinogens against 25C-NBOMe on five competency standards.