Triamterene D5, a deuterated form of Triamterene, is primarily used in research and analytical applications as an internal standard in mass spectrometry. Its stable isotopic labeling allows for precise quantification and tracking of Triamterene in biological samples, such as blood or urine. This is particularly useful in pharmacokinetic studies to monitor drug absorption, distribution, metabolism, and excretion. Additionally, it aids in the development and validation of analytical methods for detecting Triamterene in clinical and forensic settings, ensuring accurate and reliable results.