Bromadoline (U-47931E) is an opioid analgesic selective for the mu-opioid receptor developed by the Upjohn company in the 1970s. The drug has a potency lying between that of codeine and morphine being slightly stronger than pentazocine. It is presumed that the (1R,2R) isomer is the active opioid, overlaying as it does with many other mu agonists. ...