Pinky, also known as U-47700, pink heroin, pinky, and pink, is an opioid analgesic drug developed by a team at Upjohn in the 1970s which has around 7.5 times the potency of morphine in animal models.
U-47700 is a structural isomer of the earlier opioid AH-7921 and 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 activity and posted over a dozen patents on related compounds, each optimizing one moiety until they discovered that U-47700 was the most active.
This opioid became the lead compound of selective kappa-opioid receptor ligands such as U-50488, U-51754. This contains 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.
U-47700 has never been studied on humans. However, it would be expected to produce effects similar to those of other potent opioid agonists. This includes strong analgesia, sedation, euphoria, constipation, itching and respiratory depression which could be harmful or fatal. Tachycardia was another side effect encountered with U-47700 use. Tolerance and dependence would be expected to develop.
Following its sale as a designer drug, U-47700 was made illegal in Sweden on January 26, 2016.