D4-abiraterone is primarily used in research and development as an internal standard in analytical chemistry. It aids in the quantification and identification of abiraterone and its metabolites in biological samples through techniques like liquid chromatography-mass spectrometry (LC-MS). This ensures accurate and reliable measurement of abiraterone levels in pharmacokinetic studies, which is critical for understanding drug metabolism and optimizing therapeutic dosing. Its application supports advancements in cancer treatment research, particularly in prostate cancer, where abiraterone is a key therapeutic agent.