<unk>  <unk>  is an opioid antagonist used in scientific research. It is one of the few opioid antagonists available that is highly selective for the κ-opioid receptor, and blocks this receptor without affecting the μ- or δ-opioid receptors, although it has less selectivity in vivo than when used in isolated tissues.<unk>  blocks the effects of kappa agonists in animal models, and produces antidepressant effects.
Norbinaltorphimine
Levorphanol
Alfaxalone
Methoxyphedrine
Mephenoxalone
N-Methylephedrine
Triflupromazine
Butalbital