Carvedilol-d5 is primarily used in research and analytical laboratories as an internal standard in mass spectrometry. Its deuterated form allows for precise and accurate quantification of carvedilol in biological samples, such as blood or plasma, during pharmacokinetic studies. This helps in understanding the drug's absorption, distribution, metabolism, and excretion in the body. Additionally, it aids in drug development and quality control processes by ensuring reliable measurements in complex matrices. Its use is critical in clinical trials and forensic toxicology to monitor carvedilol levels and ensure patient safety and efficacy of the drug.