Invention:
This invention relates to ligands for mu, delta, and kappa opioid receptors, more particularly to ligands that are agonists for mu and delta opioid receptors, and in some cases ligands that are also antagonists for kappa opioid receptors.
Background:
Opioids are commonly used in the treatment of severe pain. Opioids have analgesic activity through their interaction with the opioid receptors (e.g., mu (μ) opioid receptor (MOR), delta (δ) opioid receptor (DOR), kappa (κ) opioid receptor (KOR)), mostly with MOR. However, the clinical use of opioids is limited by associated side effects such as respiratory depression, constipation, development of tolerance, and addiction. Indeed, chronic pain and subsequence chronic administration of a MOR agonist can lead to KOR activation, which results in undesirable adverse and addictive behaviors. For this reason, a KOR antagonist could be used to reduce such undesirable effects of chronic MOR activation.
