To evaluate the overall safety and continued efficacy of oral lixivaptan capsules in subjects with euvolemic and hypervolemic hyponatremia

Phase I and Phase II clinical trials have demonstrated that lixivaptan may play an important role in treating hyponatremia and the signs and symptoms of water retention associated with HF, LCWA and SIADH. Lixivaptan was previously evaluated in disease states characterized by hyponatremia with euvolemia (SIADH) and hyponatremia combined with fluid overload (HF, LCWA). Lixivaptan demonstrated correction in serum sodium concentration together with marked aquaresis in patients with hyponatremia.

Inclusion Criteria:

1. Men and women 18 years of age or older
2. Ability to provide informed consent or assent
3. Prior participation in a lixivaptan hyponatremia trial with evidence of continued need or desire for therapy

Exclusion Criteria:

1. A current medical condition where long-term treatment with an aquaretic agent may present an undue risk to the patient
2. Hyponatremia which is acute, reversible, artificial or due to conditions not associated with vasopressin excess or likely to respond to aquaretic therapy
3. Hyponatremia due to reversible medical condition or therapy
4. Conditions associated with an independent imminent risk of morbidity and mortality

Patients with euvolemic or hypervolemic hyponatremia and who were enrolled in a randomized, blinded, placebo-controlled Phase III lixivaptan study of hyponatremia (CK-LX3401, CK-LX3405, or CK-LX3430)