Naltrindole hydrochloride is primarily used in research settings to study the delta opioid receptor, a key target in understanding pain modulation and addiction mechanisms. It acts as a selective antagonist, blocking the receptor's activity, which helps scientists investigate its role in various physiological processes. This compound is particularly valuable in preclinical studies aimed at developing new pain management therapies, as it helps differentiate the effects of delta opioid receptors from other opioid receptor types. Additionally, it is utilized in behavioral studies to explore its potential in reducing addictive behaviors, offering insights into novel treatments for substance abuse disorders. Its specificity makes it a crucial tool in advancing our understanding of opioid receptor biology and drug development.