PRC200-SS is an arylalkanolamine TRI being developed by the Mayo Clinic.Sympathomimetic PRC200-SS is the PRC050 eutomer, whereas PRC201 is the distomer. These compounds are preceded by venlafaxine, which Wyeth claims is the first SNRI. Venlafaxine was originally developed as an "opioid" although original screening returned negative results. The authors were not satisfied just to drop venlafaxine from development and continued with their study of the compounds biological activity data. Herein, they discovered that venlafaxine exerts its biological actions via interaction with the monoamine receptors. In particular, the actions of the drug on increasing the amount of 5-HT and NE were documented, although with "potentiated" analogs such as the pm-dichlorophenyl ring substituted derivative, it might be expected to behave as a SNDRI also (but no data was available to support this inference). Venlafaxine itself has been said to behave as a SNDRI at very high doses. This would be more likely to be the case in drug naїve subjects than in users that have already built up significant tolerance.