CTOP

CTOP is an opioid antagonist cyclic peptide related to somatostatin. It has been used in research about other opioid ligands.

Pharmacology

CTOP is described as a highly potent mu-opioid receptor antagonist. In mice, its analgesic effects are qualified as being more potent than naloxone's, a well-known opioid antagonist typically used as an antidote in humans. Additionally, CTOP appears to lack significant affinity at the delta and kappa opioid receptors, suggesting that this peptide is selective for the µ receptor.