Nelivaptan is primarily investigated for its potential in treating conditions related to fluid and electrolyte imbalance, particularly those involving the vasopressin system. It acts as a selective antagonist of the vasopressin V1A receptor, which plays a key role in regulating vascular tone, cell proliferation, and stress responses. Due to this mechanism, it has been explored in the context of cardiovascular disorders, including hypertension and heart failure, where modulation of vascular constriction and cardiac workload is critical.

It has also shown interest in psychiatric and neurological research, especially in conditions like anxiety and depression, as the V1A receptor is involved in social behavior and stress regulation. By blocking this receptor, Nelivaptan may influence emotional and behavioral responses, making it a candidate for central nervous system therapeutics. However, its development has mostly remained in preclinical or early clinical stages, with limited progression into widespread therapeutic use.