pnu-181731 pnu-181731 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. it has anxiolytic effects in animal studies with around one tenth the potency of alprazolam and no significant ataxia or other side effects noted. pnu-181731identifiers iupac name 2,3,4,5-tetrahydro-1h-diazepinoindole cas number364344-56-9 ypubchem cid9794092chemspider7969859uniiuvl6vjd7ycchemical and physical dataformulac12h14n2molar mass186.258 g·mol−13d model (jsmol)interactive image smiles c12=cc=cc=c1n3c(ccncc3)=c2 inchi inchi=1s/c12h14n2/c1-2-4-12-10(3-1)9-11-5-6-13-7-8-14(11)12/h1-4,9,13h,5-8h2key:xorpzyqoyusncq-uhfffaoysa-n