Amisulpride-d5 is the stable isotope-labeled counterpart of Amisulpride. Amisulpride is an atypical antipsychotic drug mainly used to treat schizophrenia and other psychiatric disorders. Amisulpride exerts its therapeutic effects by antagonizing dopamine D2 and D3 receptors and modulating dopaminergic neurotransmission. In biomedical research, particularly in pharmacokinetic and metabolism studies, Amisulpride-d5 is used as an internal standard in analytical techniques such as high-performance liquid chromatography–high-resolution mass spectrometry (HPLC-HRMS) to improve detection sensitivity and accuracy. The dose or concentration used in experiments typically depends on the experimental design and research objectives.