PF-00356231 hydrochloride is primarily utilized in the field of pharmaceutical research and development, particularly in the study of neurological disorders. It acts as a potent and selective antagonist for the kappa opioid receptor (KOR), making it a valuable tool for investigating the role of KOR in pain management, mood regulation, and addiction. Researchers use this compound to explore potential therapeutic applications for conditions such as chronic pain, depression, and substance abuse disorders. Its specificity allows for a better understanding of the receptor's function and the development of targeted treatments with fewer side effects. Additionally, it is employed in preclinical studies to evaluate the efficacy and safety of new drugs targeting the kappa opioid receptor pathway.