PNU-181731 is a drug which acts as an agonist at serotonin 5-HT2 receptors, with strongest binding affinity for the 5-HT2C subtype at 4.8nM, and weaker 5-HT2A affinity of 18nM.
The compounds of every Wikipedia article carrying a Chembox or a Drugbox, refreshed daily, with the values their infoboxes give. The pages need JavaScript; the API does not.