Study to Evaluate the Effects of Oral Administration of Lixivaptan in Patients With Congestive Heart Failure

Diuretics are used extensively in the treatment of patients with CHF, and their efficacy is well established. However, there is a tendency for currently used diuretics to increase afterload and deplete electrolytes, and in many patients ventricular function continues to deteriorate over time. Loop diuretics, such as furosemide, also have known negative effects on renal function reducing the glomerular filtration rate, and have been shown to activate the RAA system. Lixivaptan is a potent, non-peptide selective antagonist of the vasopressin V2 receptor. Lixivaptan treatment results in increased free water excretion, thus decreasing urine osmolality, increasing urine flow, and increasing serum osmolality. Short-term treatment with lixivaptan has demonstrated improved fluid management and electrolyte balance in HF patients. This study was designed to assess the effects of vasopressin blockade with lixivaptan in patients with CHF with volume overload. A placebo-control arm will allow for assessment of the effect of lixivaptan in addition to standard diuretic therapy as compared with standard diuretic therapy alone.