FL-411 is primarily used in research settings as a selective antagonist for sigma receptors, particularly the sigma-1 receptor. Its main application lies in neuroscience and pharmacology studies, where it helps investigate the role of sigma receptors in pain modulation, neuroprotection, and psychiatric disorders such as depression and anxiety. Due to its ability to cross the blood-brain barrier effectively, FL-411 is valuable in central nervous system (CNS) studies. It has also been used in preclinical models to explore potential treatments for neuropathic pain and substance use disorders. Its selectivity makes it a useful tool for distinguishing sigma-1 mediated effects from those involving other receptor systems.