LY-281217 is a potent mu-opioid agonist with analgesic effects[1].
References
[1] M L Cohen, et al. Opioid agonist activity of ICI 174864 and its carboxypeptidase degradation product, LY281217. J Pharmacol Exp Ther. 1986 Sep;238(3):769-72. PMID:2875170