PNU-181731 is a drug which acts as an agonist at serotonin 5-HT<sub>2</sub> receptors, with strongest binding affinity for the 5-HT<sub>2C</sub> subtype at 4.8nM, and weaker 5-HT<sub>2A</sub> affinity of 18nM. It has anxiolytic effects in animal studies with around one tenth the potency of alprazolam and no significant ataxia or other side effects noted. It is a cyclized isotryptamine related to the ibogalogs.