http://3ipqoowaiaq3dk73etx45lljb4elv6jumbzcupdszhqtv6ucje4djhyd.onion?product=u-47700
Upjohn Pharmaceuticals conducted numerous studies, filing over a dozen patents to optimize specific molecular features. This process ultimately identified U-47700 as the most potent compound in its class. U-47700 became the precursor for selective kappa-opioid receptor ligands like U-50488, U-51754 (differing by a single methylene spacer), and U-69,593.