A NEW ANALGESIC APPROACH
Substantial evidence has shown that activation of kappa opioid receptors (KOR) by agonists and endogenous opioid peptides in vivo may produce a strong analgesic effect that is free from the abuse potential and the adverse side effects of mu-opioid receptor (MOR) agonists, such as morphine. In addition, activation of the KOR has also been shown to exert an inverse effect on morphine-induced adverse actions, such as tolerance, reward, and impairment of learning and memory.1
Kappa opioid receptor agonists that act within the CNS are reported to produce dysphoria and hallucinations. These symptoms have not been reported with single or multiple intravenous doses of the peripherally restricted kappa opioid receptor agonists2.
In a single-center, randomized, double-blind, active- and placebo-controlled, 4-way crossover study, overall Drug Liking and Take Drug Again VAS scores were significantly lower in either dose of a peripherally acting KORA (P<0.0001) vs. a Schedule IV drug pentazocine (0.5 mg/kg). Overall Drug Liking and Take Drug Again VAS scores following either dose of the peripherally acting KORA were similar to those observed with placebo.