2C-D

2C-D (2,5-dimethoxy-4-methylphenethylamine) is a synthetic substituted phenethylamine of the 2C structural class, bearing methoxy substituents at the 2- and 5-positions and a methyl group at the 4-position of the aromatic ring. The compound acts as a partial agonist at serotonin 5-HT2A receptors (Ki approximately 24 to 32 nM) and as a full agonist at serotonin 5-HT2C receptors (Ki approximately 13 nM; IP-1 Emax approximately 93 percent of serotonin maximum), with additional binding at the alpha-2A adrenergic receptor (Ki approximately 290 nM), trace amine-associated receptor 1 (TAAR1, rat Ki approximately 150 nM), and serotonin 5-HT2B receptors (EC50 approximately 230 nM). The compound does not interact meaningfully with monoamine transporters (DAT, SERT, NET Ki values all exceeding 10 micromolar), distinguishing it pharmacologically from the entactogen and stimulant phenethylamine classes and placing it squarely within the serotonergic psychedelic phenethylamine series.

First synthesized and published in 1970 by Ho and colleagues at the Texas Research Institute of Mental Sciences as part of a structure-activity investigation of mescaline analogs, 2C-D was subsequently characterized in human self-experimentation by Alexander Shulgin beginning in the mid-1960s and documented in the 1991 compendium PiHKAL (Phenethylamines I Have Known and Loved). Shulgin described the compound as a "pharmacological tofu" on the basis of its relatively mild standalone psychoactive profile at moderate doses (20 to 60 mg orally), its short duration of action (3 to 6 hours), and its capacity to extend or potentiate the effects of co-administered psychedelics without imposing a strong qualitative character of its own. Independent of Shulgin's work, the German psychiatrist Hanscarl Leuner employed 2C-D under the laboratory code LE-25 in psycholytic (psychedelic-assisted) psychotherapy at the University of Goettingen through the 1970s and 1980s, administering doses of up to 150 to 200 mg in supervised clinical settings.

The pharmacological profile of 2C-D has been characterized in modern receptor binding and functional assays by Eshleman et al. (2014), who demonstrated that the compound fully substitutes for the prototypical hallucinogens DOM, LSD, and DMT in rat drug discrimination paradigms (ED50 values of 0.77, 0.71, and 3.14 mg/kg, respectively), does not substitute for methamphetamine, and produces biphasic locomotor effects in mice (stimulation at 3 mg/kg, depression at 10 to 30 mg/kg, lethality at 100 mg/kg). Metabolism proceeds primarily through monoamine oxidase (MAO-A and MAO-B) mediated oxidative deamination, with secondary pathways including O-demethylation at positions 2 and 5, N-acetylation, and hydroxylation at the 4-methyl group, as characterized by Theobald et al. (2006) in rat urine using gas chromatography-mass spectrometry. The compound is not approved for any medical indication in any jurisdiction. It was placed on Schedule I of the United States Controlled Substances Act effective July 9, 2012, and is controlled in multiple additional jurisdictions including Canada, Germany, and Sweden.

This monograph documents the chemistry, structural classification, and synthesis of 2C-D; the receptor pharmacology and mechanism of action in molecular and behavioral detail; the available pharmacokinetic and metabolic data; preclinical pharmacology including drug discrimination and locomotor studies; the limited clinical and observational evidence base; sourcing and quality verification for research applications; reconstitution and handling; stack interaction considerations; the adverse-event and safety signal; and a structured comparative assessment against five related phenethylamine psychedelics (2C-B, mescaline, DOM, 2C-E, and 2C-I) on five competency standards. The compound is supplied for forensic and research purposes only and is not for human consumption.