Used primarily in neuroscience research as a selective kappa opioid receptor antagonist. It helps investigate the role of kappa opioid receptors in pain modulation, mood disorders, and addiction. Due to its long duration of action, it is valuable in studies requiring sustained receptor blockade. It is also used to examine the effects of blocking kappa receptors on stress responses and drug-seeking behavior, particularly in models of depression and substance abuse. Its selectivity makes it a critical tool for distinguishing kappa receptor-mediated effects from those involving other opioid receptors.