Issues with participant recruitment & enrollment which made the trial impossible or highly impracticable. Trial termination was not due to safety reasons.

The purpose of this trial was to demonstrate that tolvaptan effectively and safely increases and maintains serum sodium concentrations in children and adolescent participants with euvolemic or hypervolemic hyponatremia.

Inclusion:

• Male and female participants ≥4 weeks (or ≥44 weeks adjusted gestational age) to <18 years old
• Participants hospitalized with euvolemic or hypervolemic hyponatremia resistant to initial standard background therapy
• Persistent euvolemic or hypervolemic hyponatremia defined as being documented as <130 milliequivalent (mEq)/L and present for at least 48 hours, evidenced by at least 2 serum sodium assessments (12 hours apart)
• Ability to maintain adequate fluid intake (orally or intravenously)
• Ability to take oral medications
• Ability to comply with all requirements of the trial
• Completion of the trial-specific informed consent/assent as age appropriate
• Ability to commit to remain fully abstinent or practice double-barrier birth control as required by the trial

Exclusion:

• Evidence of hypovolemia or intravascular volume depletion
• Serum sodium <120 mEq/L
• Use of potent cytochrome P450 3A4 (CYP3A4) inhibitors in participants <12 kilogram (kg) or moderate CYP3A4 inhibitors in participants <6 kg
• Lacks free access to water (inability to respond to thirst) or without intensive care unit level fluid monitoring and management
• History or current diagnosis of nephrotic syndrome
• Transient hyponatremia likely to resolve
• Hyperkalemia
• Estimated glomerular filtration rate <30 milliliters/minute/1.73 meters squared
• Acute kidney injury
• Severe or acute neurological symptoms requiring other intervention
• Prior treatment for hyponatremia with hypertonic saline within 8 hours of qualifying serum sodium assessments; urea, lithium, demeclocycline, conivaptan, or tolvaptan within 4 days of qualifying serum sodium assessments; any other treatments for the purpose of increasing serum sodium concurrent with dosing of trial medication
• Anuria or urinary outflow obstruction, unless participant is/can be catheterized
• History of hypersensitivity and/or idiosyncratic reaction to benzazepine or benzazepine derivatives
• Psychogenic polydipsia
• Uncontrolled diabetes mellitus (defined as fasting glucose >300 milligrams/deciliter)
• Screening liver function values >3 times the upper limit of normal
• Participants who have cirrhosis and meet any of the following conditions: a major GI bleed within the past 6 months, evidence of active bleeding, platelet count <50,000/microliter, or use of concomitant medications known to increase bleeding risk
• Hyponatremia due to the result of any medication that can safely be withdrawn or that is most appropriately corrected by alternative therapies
• History of drug or medication abuse within 3 months prior to screening or current alcohol abuse
• Participants who require suspension formulation and have a Hereditary Fructose Intolerance
• Has hyponatremia that is more appropriately corrected by alternative therapies
• Is pregnant or currently breastfeeding
• Has any medical condition that could interfere with evaluation of trial objectives or participant safety
• Has participated in another investigational drug trial in the last 30 days
• Weighs <3 kg
• Unable to swallow tablets, if suspension unavailable
• Is deemed unsuitable for trial participation in the opinion of the investigator

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