2C-P

Discovery

Alexander Shulgin first synthesized 2C-P and documented it as entry #35 in PiHKAL (1991), assigning the compound the personal name "Selene".^[1] Self-experiments established oral activity at 6–10 mg with a duration of 10–16 hours, making it among the most potent and longest-acting compounds in the 2C series. Critically, Shulgin flagged 16 mg as a "clear overdose" and "physical disaster" — an observation that remains the single most important primary safety datum for this compound.^[1]

Market appearance and scheduling

Following ''PiHKAL'''s publication, 2C-P entered circulation through online research chemical vendors operating through the 2000s and early 2010s. Regulatory response came in waves: the United States placed 2C-P under Schedule I in 2012 via the synthetic Drug Abuse Prevention Act,^[7] Germany scheduled it in 2014, and Canada added it to Schedule III in 2016.^[8] No clinical trials or formal pharmacological characterization has ever been conducted.

Clinical documentation

Published clinical evidence is limited to two reports. A 2015 case series described five males aged 17–21 presenting with serotonergic toxicity after recreational use.^[5] A 2017 Swiss case report documented a patient who ingested 2C-P sold as 2C-B, providing the first pharmacokinetic estimate and exposing the adulterant risk inherent to unregulated markets.^[2] Both post-date US scheduling, confirming continued availability despite prohibition.

Structural class

2C-P belongs to the 2C-X family of phenethylamines, built on a 2,5-dimethoxyphenethylamine scaffold with an n-propyl chain at the 4-position of the aromatic ring. This propyl group is longer and more lipophilic than substituents on shorter-chain relatives like 2C-B (4-bromo), 2C-I (4-iodo), and 2C-E (4-ethyl). Across the 2C series, increasing the size and lipophilicity of the 4-substituent correlates with higher receptor affinity and longer duration^[9] — the propyl chain is one of the longest alkyl groups Shulgin explored, accounting for 2C-P's exceptional potency and extended action.

Molecular properties

The molecule consists of a phenethylamine backbone with methoxy groups at positions 2 and 5 and a straight-chain propyl group at position 4. The free base is an amine; the hydrochloride salt is the form most commonly encountered in forensic and analytical contexts.

Stereochemistry

2C-P is achiral — the phenethylamine backbone lacks a stereocenter at the α-carbon, unlike amphetamine-class compounds where the α-methyl group introduces chirality. No stereoisomeric considerations apply.

Physical properties

No systematic characterization of 2C-P's physical properties has been published. Melting point, solubility, and stability data are absent from peer-reviewed sources. Seized samples have been described as white powder.^[5]

Mechanism of action

2C-P acts primarily as an agonist at serotonin 5-HT₂A receptors, the molecular target responsible for psychedelic effects across the phenethylamine class. Rodent studies confirm this assignment: 2C-P produces head-twitch responses characteristic of 5-HT₂A activation, and the selective antagonist M100907 fully blocks these effects.^[6][4][10]

The 2,5-dimethoxy scaffold is essential for activity — removing either methoxy group substantially reduces psychedelic effects even when receptor binding is only modestly changed.^[11] The 4-propyl group increases lipophilicity, and across the 2C series, larger 4-position substituents progressively enhance receptor affinity.^[9]

No published study has measured specific binding strength or potency values for 2C-P at any receptor. Class-level data indicate strong 5-HT₂A affinity with partial agonist characteristics.^[9]

Secondary targets

5-HT₂C receptors represent the primary secondary target, with lower affinity than 5-HT₂A across the 2C class.^[9] Related phenethylamines show weak activity at TAAR1 (TAAR1).^[9][12] Activity at monoamine transporters is minimal or absent.^[9][12]

2C-P was among 17 2C-series compounds tested for monoamine oxidase (MAO) inhibition; across the panel, most compounds inhibited both MAO-A and MAO-B at micromolar concentrations.^[13] Whether this MAO inhibition is clinically relevant at recreational doses is uncertain but cannot be excluded.

At high doses in rodents, 2C-P altered dopamine receptor expression and DAT activity in reward-related brain regions.^[6] These dopaminergic effects were dose-dependent and absent at lower doses, suggesting they are secondary or toxicity-associated rather than part of the primary psychedelic mechanism.

Pharmacokinetics

No formal pharmacokinetic study exists for 2C-P. The best available estimate of half-life is approximately 19 hours, derived from two blood samples in a single emergency case.^[2] This aligns with the prolonged subjective duration but represents a rough approximation, not a validated population parameter.

Plasma concentrations reached approximately 20 µg/L in one sampled intoxication case; urine was positive in all five patients in the earliest case series.^[5]

The body processes 2C-P through multiple metabolic pathways including demethylation of the methoxy groups, deamination, acetylation, and conjugation reactions.^[14][15] These pathways were characterized by mass spectrometry analysis of urine, confirming analytical detectability at common doses.^[14] The specific liver enzymes involved have not been studied directly for 2C-P, though related 2C compounds suggest involvement of common drug-metabolizing enzymes.inferred

Where it acts

As a serotonin 2A receptor agonist, 2C-P is expected to act on layer V pyramidal neurons in the prefrontal cortex, increasing cortical excitability and disrupting the brain's normal filtering of sensory information. No neuroimaging or electrophysiological data have been published for 2C-P specifically — neural effects are inferred from the broader psychedelic literature on compounds like psilocybin and LSD.citation needed

At high doses in rodents, 2C-P altered dopamine signaling in the nucleus accumbens and prefrontal cortex,^[6] suggesting engagement of reward circuitry beyond the typical serotonergic psychedelic profile. Microglial activation observed in the striatum at these doses points to possible neuroinflammatory processes.^[6]

Why it matters

The relaxed beliefs under psychedelics (REBUS) model offers the most relevant framework: 5-HT₂A agonism loosens the brain's reliance on prior expectations, allowing raw sensory and emotional signals greater access to conscious experience. 2C-P's prolonged duration — potentially an entire waking day of altered cortical dynamics — may produce deeper destabilization of established belief patterns than shorter-acting psychedelics, though this remains speculative. Whether 2C-P promotes structural brain changes (neuroplasticity) as demonstrated for other psychedelics has not been tested.

Toxicity

Clinical presentations in published cases include dilated pupils, severe agitation, confusion, visual hallucinations, rapid heart rate, and elevated blood pressure.^[5] One case involved substance misidentification — the patient believed he was consuming 2C-B.^[2] All documented cases resolved with supportive care.

Psychological risks

2C-P's combination of high potency, steep dose–response curve, long duration, and delayed onset creates elevated risk for prolonged distressing experiences. At doses above the common range, severe agitation, confusion, and frightening hallucinations are documented.^[2][5]

The slow onset increases the risk of premature redosing — taking more because "nothing is happening" — which given the steep dose–response curve can transform a manageable experience into an overwhelming one. Ego dissolution, delusions, and thought loops can be intensely distressing when unexpected or prolonged over many hours.

No data exist on HPPD (HPPD) following 2C-P use. The prolonged receptor engagement suggests theoretical risk, but clinical rarity of HPPD across all psychedelics and absence of 2C-P-specific reports prevent quantification.inferred

Tolerance and dependence

Tolerance to 2C-P's psychedelic effects develops rapidly after a single dose, driven by downregulation of 5-HT₂A receptors in the brain.^[3][4] Cross-tolerance extends to all serotonergic psychedelics: LSD, psilocybin, mescaline, and other 2C compounds.^[4][3]

Physical dependence liability is low — no withdrawal has been documented for any 2C-class compound. However, rodent studies complicate the picture: dose-dependent conditioned place preference in mice and increased self-administration in rats suggest reinforcing properties atypical for classical psychedelics.^[6] These findings may relate to dopaminergic effects at high doses and suggest that 2C-P's dependence profile may not be identical to the broader psychedelic class.

Drug interactions

The primary interaction risk is serotonin toxicity when 2C-P is combined with other serotonergic agents. 2C-P contributes through direct 5-HT₂A agonism and possible monoamine oxidase inhibition.^[13]

Tramadol is flagged as a dangerous combination. Tramadol's serotonin and norepinephrine reuptake inhibitor, combined with 2C-P's receptor agonism and possible MAO inhibition, creates a plausible pathway to serotonin syndrome.safety citation needed

SSRIs and SNRIs may blunt or block psychedelic effects through chronic receptor adaptation while simultaneously increasing serotonin syndrome risk through additive serotonergic load. Lithium combined with serotonergic psychedelics carries risk of seizures and serotonin toxicity.safety citation needed

MAOIs present a dual risk: 2C-P itself exhibits MAO inhibition in laboratory testing,^[13] and external MAO inhibitors would further amplify serotonergic activity, substantially increasing serotonin syndrome risk.

Cannabis interaction data do not exist for 2C-P. Cannabis may amplify or unpredictably modify psychedelic effects. Given 2C-P's long duration and steep dose–response curve, any potentiation carries elevated risk.

Contraindications

Contraindication data specific to 2C-P do not exist. The following are inferred from its pharmacological classinferred:

• Psychotic disorders or family history of psychosis: 5-HT₂A agonism may trigger or worsen psychotic episodes.
• Bipolar disorder: Risk of manic or mixed episode precipitation.
• Heart conditions: Rapid heart rate and elevated blood pressure are consistently reported; individuals with pre-existing cardiac conditions face elevated risk.
• Seizure disorders: Serotonergic excess may lower seizure threshold; related 2C compounds have produced seizures in case reports.^[17]
• Liver impairment: Extensive liver metabolism suggests altered clearance in hepatic dysfunction, though no specific data exist.
• Pregnancy and breastfeeding: No reproductive toxicity data exist; 5-HT₂A agonism during fetal development is a theoretical concern.
• Concurrent serotonergic medication: See Drug Interactions above.

2C-P is controlled in multiple jurisdictions, primarily through specific scheduling of 2C-class phenethylamines or under broader structural analog legislation. No jurisdiction has approved 2C-P for medical or research use.

Analog act considerations

In jurisdictions with analog legislation, 2C-P's structural similarity to other controlled phenethylamines may provide an additional basis for prosecution independent of specific scheduling. In the United States, 2C-P is now explicitly listed under Schedule I, making the Federal Analogue Act unnecessary — but analog provisions remain relevant in jurisdictions where 2C-P is not specifically named.