3-Methoxyphencyclidine (3-MeO-PCP) is a dissociative hallucinogen of the arylcyclohexylamine class related to phencyclidine (PCP) which has been sold online as a designer drug. It acts mainly as an NMDA receptor antagonist, though it has also been found to interact with the sigma σ1 receptor and the serotonin transporter. The drug does not possess any opioid activity nor does it act as a dopamine reuptake inhibitor.
3-MeO-PCP has a Ki of 20 nM for the dizocilpine (MK-801) site of the NMDA receptor, 216 nM for the serotonin transporter (SERT), and 42 nM for the sigma σ1 receptor. It does not bind to the norepinephrine or dopamine transporter nor to the sigma σ2 receptor (Ki >10,000 nM). Based on its structural similarity to 3-hydroxy-PCP (3-HO-PCP), which uniquely among arylcyclohexylamines has high affinity for the μ-opioid receptor in addition to the NMDA receptor, it was initially expected that 3-MeO-PCP would have opioid activity. However, radioligand binding assays with human proteins have shown that, contrary to common belief, the drug also does not interact with the μ-, δ-, or κ-opioid receptors at concentrations of up to 10,000 nM. As such, the notion that 3-MeO-PCP has opioid activity has been described as a myth.
3-MeO-PCP binds to the NMDA receptor with higher affinity than PCP and has the highest affinity of the three isomeric anisyl-substitutions of PCP, followed by 2-MeO-PCP and 4-MeO-PCP.