SR 49059 is primarily used in research settings as a selective vasopressin V1a receptor antagonist. It is employed to study the role of vasopressin in physiological processes such as blood pressure regulation, water retention, and cardiovascular function. Due to its ability to block V1a receptors, it has been investigated for potential applications in conditions involving abnormal vasoconstriction, heart failure, and hypertension. It also serves as a pharmacological tool to understand the signaling pathways and effects of arginine vasopressin in both central and peripheral tissues. Its use remains largely confined to experimental models and is not approved for clinical use in humans.