Hebei Kaiyou Biological Technology Co, Ltd

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 in animal models

U-47700 is a structural isomer of the earlier opioid AH-7921and the result of a great deal of work elucidating the quantitative structure–activity relationship of the scaffold. Upjohn looked for the key moieties which gave the greatest activityand posted over a dozen patents on related compounds, each optimizing one moiety until they discovered that U-47700 was the most active.

U-47700 became the lead compound of selective kappa-opioid receptor ligands such as U-50488, U-51754 (containing a single methylene spacer difference) and U-69,593, which share very similar structures. Although not used medically, the selective kappa ligands are used in research.