U-49900 is a fairly new invention, and it does not yet appear to be specifically illegal in any major world jurisdiction. However, many countries make analogues of known prohibited chemicals illegal as well, so check your local regulations carefully before ordering.
U-49900 is a relatively new opioid research chemical that has been generating a great deal of attention recently. It is a powerful opioid, and a very close analogue of the better-known U-47700.
It is also called trans-3,4-dichloro-N-[2-(diethylamino)cyclohexyl]-N-methyl-benzamide. Its chemical formula is C18H26Cl2N2O.
Pharmacology: U-49900 is being explored for its potential as an analgesic painkiller. It is similar to its parent compound, U-47700, except that two of the tail ring’s methyl groups have been replaced with ethyl groups. It is fairly selective for the µ-opioid receptor, and seems to be 7 to 8 times as potent as classic morphene in animal tests.