Vasopressin: A new target for the treatment of heart failure

Background: Arginine vasopressin is a peptide hormone that modulates a number of processes implicated in the pathogenesis of heart failure. Numerous vasopressin antagonists are currently under development for the treatment of this syndrome. Methods: Preclinical and clinical data describing the effects of vasopressin and the vasopressin antagonists on both normal physiology and heart failure were reviewed. Results: Through activation of V_1a and V₂ receptors, vasopressin regulates various physiological processes including body fluid regulation, vascular tone regulation, and cardiovascular contractility. Vasopressin synthesis is significantly and chronically elevated in patients with heart failure despite the volume overload and reductions in plasma osmolality often observed in these patients. Vasopressin also appears to adversely effect hemodynamics and cardiac remodeling, while potentiating the effects of norepinephrine and angiotensin II. The selective V₂ and dual V_1a/V₂ receptor antagonists tolvaptan and conivaptan, respectively, substantially increase free water excretion and plasma osmolality, reduce body weight, improve symptoms of congestion, and moderately increase serum sodium concentrations in patients with heart failure who present with symptoms of fluid overload. Tolvaptan effectively normalizes serum sodium concentrations in hyponatremic heart failure patients. Conivaptan significantly reduces pulmonary capillary wedge pressure without affecting systemic vascular resistance or cardiac output. The clinical significance of V_1a receptor antagonism requires further investigation. Conclusions: Current preclinical and clinical findings with the vasopressin antagonists appear promising, however further evaluation in phase III clinical trials is necessary to define the role of vasopressin antagonism in the treatment of heart failure.