 This inactive product, as well as the inactive 2-ethyl-5-methyl-3,3- 
diphenyl-1-pyrroline (EMDP), produced by a second "N"-demethylation, are detectable in the urine of those taking methadone.The most common route of administration at a methadone clinic is in a racemic oral solution, though in Germany, only the "R" enantiomer (the L optical isomer) has traditionally been used, as it is responsible for most of the desired opioid effects.The single-isomer form is becoming less common due to the higher production costs.