3-MeO-PCP: general

3-MeO-PCP is a dissociative drug related structurally to phencyclidine (PCP) [1][2]. It works mainly by blocking NMDA receptors in the brain, and in vitro and in vivo studies show it binds these receptors more effectively than PCP or ketamine [3][2]. That stronger binding is a pharmacological finding, not a dosing guide — there is no reliable dose or duration information in wide circulation for this substance, and human data overall is thin: two subjects have been involved in analytically confirmed non-fatal intoxication with the drug [4][1]. It has been around on the grey market since 2010 and saw wider distribution from 2011, but "available" and "understood" are different things — little is known about it even where it circulates [4][1].

What this means in practice: the half-life has been estimated at 10–11 hours [3]. The drug is also extensively metabolized into at least 30 different breakdown products [3].

As with dissociatives generally, this class can cause respiratory depression, heart rate abnormalities, and a withdrawal syndrome with regular use [5]. Overdose on dissociatives as a class can range from unpleasant to life-threatening depending on dose, route, and whether other substances are involved, with signs including severe nystagmus (eye jerking), unresponsiveness, vomiting while unconscious, severely depressed breathing, seizures, and dangerously elevated heart rate or blood pressure [6].

Given how little is confirmed about this specific compound, treat any dose as a first dose: start far lower than seems reasonable, wait, and don't combine it with anything else. Never use it alone. Use a reagent test kit to check identity, and use a drug checking service if one is available to you [6].

References

1. Two Cases of Non-fatal Intoxication with a Novel Street Hallucinogen: 3-Methoxy-Phencyclidine - PubMed — PubMed / Journal of Analytical Toxicology
2. 3-MeO-PCP — Wikipedia
3. New Psychoactive Substances 3-Methoxyphencyclidine (3-MeO-PCP) and 3-Methoxyrolicyclidine (3-MeO-PCPy): Metabolic Fate Elucidated with Rat Urine and Human Liver Preparations and their Detectability in Urine by GC-MS, LC-(High Resolution)-MSn and LC-(High Resolution)-MS/MS — Current Neuropharmacology / PMC
4. 3-MeO-PCP_Final Report_A — World Health Organization
5. Hallucinogens and Dissociatives — National Institute on Drug Abuse (NIDA)
6. Dissociatives: Dosage, Effects, Duration & Safety Guide — SubstanceWiki