Norverapamil-d7 hydrochloride is primarily used in research and development as an internal standard in analytical chemistry. It aids in the accurate quantification of norverapamil and related compounds in biological samples using techniques like liquid chromatography-mass spectrometry (LC-MS). This labeled compound ensures precision in pharmacokinetic studies, helping researchers understand drug metabolism and distribution. Its deuterium labeling minimizes interference, making it a reliable tool for method validation and quality control in pharmaceutical analysis.