Detection in biological fluids<unk>  and its major metabolite, 2-ethylidene-1,5-dimethyl-3,3-diphenylpyrrolidine (EDDP), are often measured in urine as part of a drug abuse testing program, in plasma or serum to confirm a diagnosis of poisoning in hospitalized victims, or in whole blood to assist in a forensic investigation of a traffic or other criminal violation or a case of sudden death.<unk>  usage history is considered in interpreting the results as a chronic user can develop tolerance to doses that would incapacitate an opioid-naive individual. Chronic users often have high<unk>  and EDDP baseline values. Conformation The protonated form of<unk>  takes on an extended conformation, while the free base is more compact. In particular, it was found that there is an interaction between the tertiary amine and the carbonyl carbon of the ketone function (R3N ••• >C=O) that limits the molecule's conformation freedom, though the distance (291 pm by X-ray) is far too long to represent a true chemical bond. However, it does represent the initial trajectory of attack of an amine on a carbonyl group and was an important piece of experimental evidence for the proposal of the Bürgi–Dunitz angle for carbonyl addition reactions.
Methadone
Isomethadone
Normethadone
Levomethadone
Morphine
Buprenorphine
Codeine
Naltrexone