Lisinopril-d5 is primarily used in research and analytical laboratories as an internal standard for the quantification of lisinopril in various biological samples. It aids in ensuring accuracy and precision in mass spectrometry and chromatography studies, particularly in pharmacokinetic and pharmacodynamic research. This deuterated compound helps in distinguishing the analyte from endogenous substances, improving the reliability of drug metabolism and bioavailability studies. Additionally, it supports the development of sensitive and specific analytical methods for therapeutic drug monitoring in clinical settings.