They found damage to neurons associated with serotonin. Areas particularly affected, they reported in the Journal of Neuroscience, were the neocortex, the outer part of the brain which is associated with conscious thought, and the hippocampus, associated with long-term memory. Six to seven monkeys were killed and their brains were examined. Ricaurte said they had not recovered from the damage. The pharmaceutical drug, fentanyl, was originally created for anesthesia during surgeries.
Designer drugs derived from fentanyl are extremely potent and have a strong potential for overdose.
Fentanyl-based designer drug's effects are short lived, about 30 to 90 minutes. Sometimes fentanyl-derived designer drugs are injected. Increasingly the drug is sniffed or smoked, in part to avoid the risk of getting HIV via infected needles. Fentanyl-derived designer drugs are extremely dangerous. The respiratory paralysis that may occur is so sudden after drug administration that often victims who injected the drug are found with the needle still in their arm.