Apixaban 13C d3 is primarily used as an internal standard in analytical chemistry for the quantification of apixaban in biological samples. Its stable isotope labeling ensures accurate and precise measurements in mass spectrometry, aiding in pharmacokinetic studies, drug metabolism research, and therapeutic drug monitoring. This compound is essential for ensuring the reliability of data in clinical and pharmaceutical research, particularly in studies involving the anticoagulant effects of apixaban.