I wonder why research on kappa opioid antagonists is so scarce and scattered. i’ve heard Kappa blockade shows promise in treating depression, reward deficiency as well as chronic stress and trauma. rather unusually, kappa opioid antagonism has shown antipsychotic potential which is paradoxical given that it can considerably enhance dopamine signalling. personally, I think research slowed down and many potential benefits went unnoticed after scientist switch from the ultra long acting/irreversible Kappa antagonists to Very weak ultra short acting often partial antagonists. this was done after one particular antagonist caused cardiac arrhythmia in a medical trial many years ago, but it is unfortunate, because it may be that long term Kappa opioid antagonism is needed for the full benefits to be realised.