Biogen Idec and Cardiokine, Inc. initiated a Phase III study of lixivaptan for congestive heart failure patients who suffer from hyponatremia, which is an electrolyte disturbance marked by low sodium levels in the blood. The trial will compare treatment with lixivaptan to placebo in approximately 650 patients in the U.S. and Europe.     Lixivaptan is an oral vasopressin V2 receptor antagonist that works by causing a decrease in renal water reabsorption (an increase in urine volume) and a decr...