6β-Naltrexol-d3 is primarily utilized in research and analytical applications, particularly in the field of pharmacology. It serves as an internal standard in mass spectrometry-based assays for the quantification of naltrexone and its metabolites in biological samples. This deuterated compound enhances the accuracy and reliability of analytical measurements due to its isotopic labeling, which minimizes interference from endogenous substances. Additionally, it aids in studying the pharmacokinetics and metabolic pathways of naltrexone, providing insights into its efficacy and safety profile in clinical settings. Its use is critical in advancing understanding of opioid receptor modulation and related therapeutic interventions.