Enadoline is a drug which acts as a highly selective κ-opioidagonist.
In human studies, it produced visual distortions and feelings of dissociation, reminiscent of the effects of salvinorin A.[1]
It was studied as a potential analgesic, but abandoned because of the dose-limiting effects of dysphoria, which could be expected from a κ-opioid agonist. There was mention of its potential in treating comatose head injury or stroke victims, where that type of side effect would be immaterial.[2]
Potency
When enadoline was first reported in 1990, it was "the most potent κ-selective analgesic ever reported ... 25 times more potent than morphine and 17 times more potent than U-62066".[3]