Utopioids (U-type opioids) are a class of syntheticopioidanalgesic drugs first developed in the 1970s by the pharmaceutical companyUpjohn.[1] However, they were never marketed for medical use. Some compounds from this class have been used for scientific research as modelkappa opioid receptor agonists. In the mid-2010s, onemu opioid receptor selective compound from this class,U-47700, re-emerged as adesigner drug and became widely sold around the world for several years before being banned in various jurisdictions from 2016 onwards. Following the prohibition of U-47700, a number of related compounds have continued to appear on illicit drug markets. They are often marketed online or included as components in mixtures sold under the guise of "street heroin." U-47700 itself is the most potent mu opioid agonist from this class, with around 7 to 10 times the potency ofmorphine. Some other compounds such as3,4-MDO-U-47700 and N-Ethyl-U-47700 retain similar mu selectivity but with lower potency similar to that of morphine, while others have a mixture of mu- and kappa-mediated effects, such asU-48800. Most utopioid derivatives are, however, selective kappa agonists, which may have limited abuse potential as dissociative hallucinogens, but do not alleviate withdrawal distress in opioid dependent individuals or maintain addiction in a typical sense. Nevertheless, this has not stopped them from being sold as designer drugs, and a number of these compounds are now banned in many jurisdictions alongside U-47700 itself.[2][3][4][5][6][7][8][9]
| Structure | Name | PubChem | CAS # |
|---|---|---|---|
 | U-47109 | 44269286 | 67579-13-9 |
 | U-47700 | 13544016 | 82657-23-6 |
 | U-47931E (Bromadoline) | 6328449 | 2418521-61-4 |
 | U-48520 | 13544026 | 67579-11-7 |
 | U-48800 | 137700072 | 2370977-17-4 |
 | U-49900 | 129392412 | 67579-76-4 |
 | U-50211[10] | 13544017 | 98587-47-4 |
 | U-50488 | 3036289 | 67198-13-4 |
 | U-51574 | 44269303 | |
 | U-62066 (Spiradoline) | 55652 | 87151-85-7 |
 | U-69593 | 105104 | 96744-75-1 |
 | U-77891 | 117071705 | 119878-31-8 |
 | N-Desmethyl-U-47700 | 129390993 | 67579-73-1 |
 | N,N-Didesmethyl-U-47700 | 129406364 | 2616858-81-0 |
 | 3,4-MDO-U-47700 | 139598237 | 2488874-96-8 |
 | 3,4-Ethylenedioxy-U-47700 | 137700298 | 2749619-08-5 |
 | 3,4-Ethylenedioxy-U-51574 | 137700374 | 2748623-91-6 |
 | N-Ethyl-U-47700 | 155907846 | |
 | N-Propyl-U-47700 | 137700434 | 2749433-76-7 |
 | N-Isopropyl-U-47700 | 137700166 | 2748319-16-4 |
 | N-Cyclopropyl-U-47700 | 165361451 | |
 | N-Methoxy-U-47700 | 155907659 | |
 | N-Methyl-U-47931E | 54482637 | 75570-38-6 |
 | 3,4-Dibromo-U-47700 | ||
 | 3,4-Difluoro-U-47700 | 165362347 | 2417942-54-0 |
 | 2,4-Difluoro-U-48800 | ||
 | 4-TFM-U-48520 (U-04) | 53720446 | 67579-38-8 |
 | α-U10 | 165362154 | 2417942-61-9 |
 | β-U10 | 54524276 | 67579-80-0 |