Synthesis and Pharmacology of a Morphinan-Derived Dual Mu-Kappa Opioid Receptor Agonist Analgesic

We present the synthesis and pharmacological characterization of 3'-iodobenzoylamido epoxymorphinans, with a saturated ring C and devoid of 14-OH, based on a dihydronormorphine backbone with various N-17 alkyl substitutions. All synthesized compounds were characterized pharmacologically in radioligand binding assays, [³⁵S]GTPγS functional assays, and for antinociception in mice. Among these analogues, MP1202, a pan-opioid receptor analogue, was characterized further in β-arrestin1/2 studies, G-protein recruitment and Gα-subtype profiling, as well as by evaluation of opioid-mediated effects in mice. MP1202 exhibits potent antinociceptive effects in mice without causing typical opioid side effects, such as respiratory depression and physical dependence. However, it displays conditioned place preference and aversion behaviors similar to those of classical mu and kappa agonists.