semorphone semorphone semorphone (mr 2264) is an opiate analogue that is an n-substituted derivative of oxymorphone. semorphoneclinical dataatc codenoneidentifiers iupac name (5α)-4,5-epoxy-3,14-dihydroxy-17-(2-methoxyethyl)morphinan-6-one cas number88939-40-6pubchem cid5491906chemspider4590760 yunii2hd55617i2comptox dashboard (epa)dtxsid00933465 chemical and physical dataformulac19h23no5molar mass345.395 g·mol−13d model (jsmol)interactive image smiles o=c45oc1c2c(ccc1o)c3n(cc253(o)cc4)ccoc inchi inchi=1s/c19h23no5/c1-24-9-8-20-7-6-18-15-11-2-3-12(21)16(15)25-17(18)13(22)4-5-19(18,23)14(20)10-11/h2-3,14,17,21,23h,4-10h2,1h3/t14-,17+,18+,19-/m1/s1 ykey:pbgibllomgurps-grgslbftsa-n y (verify) semorphone is a partial agonist at μ-opioid receptors. it is around twice the potency of morphine, but with a ceiling effect on both analgesia and respiratory depression which means that these effects stop becoming any stronger after a certain maximum dose. it is not currently used in medicine, and is not a controlled drug, although it might be considered to be a controlled substance analogue of oxymorphone on the grounds of its related chemical structure in some jurisdictions such as the united states, canada, australia and new zealand.