Adefovir-d4 Diphosphate Triethylamine Salt is primarily used in research and development within the pharmaceutical industry, particularly in the study of antiviral therapies. It serves as a deuterated analog of adefovir diphosphate, which is an active metabolite of adefovir, a nucleotide reverse transcriptase inhibitor. This compound is utilized in pharmacokinetic and metabolic studies to understand the behavior, distribution, and efficacy of adefovir in treating viral infections such as hepatitis B. Its deuterated form allows for more precise tracking and analysis in mass spectrometry and other analytical techniques, aiding in the development of improved antiviral drugs. Additionally, it is employed in the synthesis of labeled compounds for use in clinical trials and drug testing.