An Extension Follow-up Trial to Evaluate the Long-term Safety of Children and Adolescent Participants With Euvolemic or Hypervolemic Hyponatremia

Exclusion criteria

• ✕. Male and female participants ≥ 4 years of age (or per local Health Authority age restrictions) and ≥ 10 kilograms (kg).
• ✕. Participant must have been off treatment with the investigational medicinal product for at least 7 days following the end of treatment in the previous tolvaptan trial for hyponatremia (euvolemic or hypervolemic).
• ✕. Persistent dilutional (euvolemic or hypervolemic) hyponatremia defined as being documented as present for at least 48 hours, evidenced by at least 2 serum sodium assessments \< 130 milliequivalents (mEq)/liter (L) (millimole \[mmol\]/L) drawn at least 12 hours apart (these values can be documented using historical values previously obtained per standard of care); a third (STAT) serum sodium assessment \< 130 mEq/L (mmol/L), which will serve as the baseline value for efficacy endpoints, had to be obtained within 2 to 4 hours prior to the first dose of tolvaptan.
• ✕. Ability to swallow tablets.
• ✕. Ability to maintain adequate fluid intake whether orally or via intravenous support with adequate monitoring.
• ✕. Ability to comply with all requirements of the trial.
• ✕. Trial-specific written informed consent/assent obtained from a parent/legal guardian or legally acceptable representative, as applicable per age of participant or local laws, prior to the initiation of any protocol-required procedures. In addition, the participant as required by local laws must provide informed assent at the pretreatment baseline for this trial and must be able to understand that he or she can withdraw from the trial at any time. All informed consent/assent procedures must be in accordance with the trial center's Institutional Review Board/Independent Ethics Committee and local regulatory requirements.