ABSTRACT
Opioid analgesics are potent pain-killer and are widely used in clinical practice.Opioid receptors are classified into μ,δ,κ subtypes.Most of the currently available opioid analgesics are μ opioid receptor agonists, but they cause undesired side effects such as physical dependence, respiratory depression and constipation and so on.The antalgic activity of δ receptor agonist is weaker than that of μ agonist, but it can modulate the activity of μ receptor and prevent its addiction. Therefore, discovering and designing compounds with μ/δ dual action is a new way for finding analgesics with low toxicity and less side effects.This review summarizes the development of compound with dual μ/δ activities and provides a new strategy for designing analgesics with low toxicity and less side effects.