Lovastatin-d3 hydroxy acid sodium is primarily used in research and development as an internal standard in analytical chemistry. It is employed in quantitative mass spectrometry to ensure accurate measurement of lovastatin and its metabolites in biological samples. This compound helps in pharmacokinetic studies, enabling researchers to track drug absorption, distribution, metabolism, and excretion with high precision. Its deuterated form minimizes interference, enhancing the reliability of analytical results in clinical and pharmaceutical research.