naltalimide naltalimide naltalimide (inn) (code name trk-130, formerly tak 363) is a novel, centrally-acting opioid drug which is under development by takeda and toray for the treatment of overactive bladder/urinary incontinence. it acts as a potent and selective partial agonist of the μ-opioid receptor (ki = 0.268 nm, ec50 = 2.39 nm, emax = 66.1%) over the δ-opioid (ki = 121 nm, ec50 = 26.1 nm, emax = 71.0%) and κ-opioid receptors (ki = 8.97 nm, ec50 = 9.51 nm, emax = 62.6%). notably, naltalimide somehow appears to lack certain undesirable side effects such as constipation seen with other μ-opioid receptor agonists such as morphine. it enhances bladder storage via suppression of the afferent limb of the micturition reflex pathway. naltalimideclinical dataatc codenoneidentifiers iupac name 2--1h-isoindole-1,3(2h)-dione cas number160359-68-2pubchem cid16066809chemspider17226389uniipuo0lms4nxcomptox dashboard (epa)dtxsid10166868 chemical and physical dataformulac28h28n2o5molar mass472.541 g·mol−13d model (jsmol)interactive image smiles c1ccc2c(c1)c(=o)n(c2=o)3cc4(5cc6ccc(c7c64(3o7)ccn5cc8cc8)o)o inchi inchi=1s/c28h28n2o5/c31-20-8-7-16-13-21-28(34)10-9-19(30-25(32)17-3-1-2-4-18(17)26(30)33)24-27(28,22(16)23(20)35-24)11-12-29(21)14-15-5-6-15/h1-4,7-8,15,19,21,24,31,34h,5-6,9-14h2/t19-,21-,24+,27+,28-/m1/s1key:dhaitnwjdosrbu-ibhwkqipsa-n