olorinab olorinab olorinab (apd371) is a drug being developed by arena pharmaceuticals for the treatment of gastrointestinal pain associated with crohn's disease and irritable bowel syndrome. it acts as a potent and selective cannabinoid cb2 receptor agonist and is claimed to be orally active and peripherally selective. initial phase iia exploratory clinical trials have been successful in patients with quiescent crohn's disease. arena initiated the phase iib captivate trial in late july 2019 in patients with irritable bowel syndrome related pain, in constipation and diarrhea predominant sub-types. the phase iib trial is expected to enroll 240 participants between the ages of 18 to 70.three doses of 10 mg, 25 mg, and 50 mg are being tested against placebo in a 3:4 prescription ratio with a quadruple (participant, care provider, investigator, outcomes assessor) masking layout. olorinabclinical dataroutes ofadministrationoralidentifiers iupac name (4as,5as)-n-((2s)-1-hydroxy-3,3-dimethylbutan-2-yl)-1-(4-oxidopyrazin-2-yl)-4,4a,5,5a-tetrahydro-1h-cyclopropa(4,5)cyclopentapyrazole-3-carboxamide cas number1268881-20-4pubchem cid60164925unii581f7dfa9bkeggd11429chemical and physical dataformulac18h23n5o3molar mass357.414 g·mol−13d model (jsmol)interactive image smiles cc(c)(c)(co)nc(=o)c1=nn(c2=c1c32c3)c4=nc=c(=c4) inchi inchi=1s/c18h23n5o3/c1-18(2,3)13(9-24)20-17(25)15-12-7-10-6-11(10)16(12)23(21-15)14-8-22(26)5-4-19-14/h4-5,8,10-11,13,24h,6-7,9h2,1-3h3,(h,20,25)/t10-,11-,13+/m0/s1key:acsqltbpyzsgba-gmxvviovsa-n in 2019, a study showed that olorinab reduces visceral hypersensitivity in the tnbs-induced colitis animal model, attempting to control for its mechanism of action by using a cb2 antagonist (sr-144,528). results were favorable showing reduced visceral hypersensitivity in animal models of ibd and ibs but not in healthy controls, suggesting that activation of cb2 causes antinociceptive actions in visceral sensory pathways in models of ibd and ibs. also, sr-144528 prevented olorinab-induced inhibition of colonic nociceptor hypersensitivity, further validating the role of the cb2 receptor in nociception.