Product Description: 4-Hydroxy-1-(2-phenylethyl)piperidine is a building block that has been used in the synthesis of ligands of the muscarinic acetylcholine receptor (mAChR) or sigma non-opioid intracellular receptor 1 (σ1 receptor). 4-Hydroxy-1-(2-phenylethyl)piperidine is also a metabolite of the opioids furanyl fentanyl and 4-fluoroisobutyryl fentanyl (FIBF).