Vasopressin antagonists in heart failure.

The recrudescence of interest in manipulation of the arginine vasopressin system and especially of V2 vasopressin receptor blockade in heart failure stems from the limited efficacy and possible detrimental effects of loop diuretics. The "braking phenomenon," hypertrophy of the collecting duct cells, and altered pharmacodynamics contribute to loop diuretic resistance in heart failure. Selective (tolvaptan) and nonselective (conivaptan) V2 vasopressin receptor antagonists now known as "vaptans" promote free-water excretion that is labeled aquaresis and correct hyponatremia in patients with severe heart failure. A large mortality study with tolvaptan in heart failure is presently ongoing.