Bazedoxifene-d4 N-Oxide is primarily used in research and development as a deuterated analog of bazedoxifene, a selective estrogen receptor modulator (SERM). Its application is significant in pharmacokinetic and metabolic studies, where it serves as an internal standard in mass spectrometry-based assays. This helps in accurately quantifying bazedoxifene levels in biological samples, ensuring precise measurement of drug absorption, distribution, metabolism, and excretion. Additionally, it aids in understanding the drug's interaction with estrogen receptors, contributing to the development of targeted therapies for conditions like osteoporosis and breast cancer. Its deuterated form enhances analytical accuracy by minimizing interference in detection methods.