U-47700, street name pinky or pink, is an opioid analgesic drug developed by a team at Upjohn in the 1970sthat acts as a selective agonist of the µ-opioid receptor with a Kd value of 5.3 nM compared to 910 nM for the κ-opioid receptorand has around 7.5 x the potency of morphine...