Cabotegravir-d3 is primarily used in research and development as an internal standard in analytical chemistry. It aids in the quantification and identification of cabotegravir in biological samples through techniques like liquid chromatography-mass spectrometry (LC-MS). This deuterated compound ensures accuracy and reliability in pharmacokinetic studies, helping researchers understand drug metabolism, distribution, and elimination. Its application is critical in the development and monitoring of long-acting antiretroviral therapies for HIV treatment.