XOB, also known as ASR-6001 or as N-[(4-phenylbutoxy)hexyl]-4-bromo-2,5-dimethoxyphenethylamine, is a serotonin 5-HT<sub>2A</sub> receptor antagonist and voltage-gated sodium channel (VGSC) blocker of the phenethylamine and 2C families. It is a derivative of 2C-B in which the amine-containing side chain has been extended with the same long group found in salmeterol.
The drug is of relatively low potency as a serotonin 5-HT<sub>2A</sub> receptor antagonist. It shows modest selectivity for the serotonin 5-HT<sub>2A</sub> receptor over the serotonin 5-HT<sub>2B</sub> and 5-HT<sub>2C</sub> receptors. XOB was accidentally found to have local anesthetic properties upon contact with human skin, which led to the elucidation of its sodium channel-blocking activity.
XOB was developed in part by researchers at the Alexander Shulgin Research Institute (ASRI).