What is this medication?
Tolvaptan, Samsca is indicated for treatment of hypervolemic or euvolemic hyponatremia.
“ALERT: US Boxed Warning
Treatment initiation and monitoring (Samsca):
Tolvaptan, Samsca should be initiated and reinitiated in patients only in a hospital where serum sodium can be closely monitored.
Too rapid correction of hyponatremia (eg, more than 12 mEq/L per 24 hours) can cause osmotic demyelination, resulting in dysarthria, mutism, dysphagia, lethargy, affective changes, spastic quadriparesis, seizures, coma, and/or death. In susceptible patients, including those with severe malnutrition, alcoholism, or advanced liver disease, slower rates of correction may be advisable.
Use of tolvaptan for autosomal dominant polycystic kidney disease outside of FDA-approved REMS:
Because of the risk of hepatotoxicity, tolvaptan (Samsca) should not be used for autosomal dominant polycystic kidney disease (ADPKD) outside of the FDA-approved REMS."
How does this medication work?
Tolvaptan, Samsca is an arginine vasopressin (AVP) receptor antagonist with affinity for AVP receptor subtypes V2 and V1a. Antagonism of the V2 receptor by tolvaptan promotes the excretion of free water (without loss of serum electrolytes) resulting in net fluid loss, increased urine output, decreased urine osmolality, and subsequent restoration of normal serum sodium levels.
How should I take this medication?
Oral: Initial: 15 mg once daily; after at least 24 hours, may increase to 30 mg once daily to a maximum of 60 mg once daily titrating at 24-hour intervals to desired serum sodium concentration. Avoid fluid restriction during the first 24 hours of therapy. Do not use for more than 30 days due to the risk of hepatotoxicity.
How to Take: Samsca treatment should be initiated or reinitiated in a hospital. May be administered without regards to meals. Water should be always available during use and patients encouraged to drink to avoid thirst and prevent dehydration from occurring. Interrupt therapy if the ability to drink or accessibility to water is limited.
You Need to Avoid: Grapefruit juice may increase tolvaptan serum concentrations.
What should I watch for while using this medication?
Before starting Tolvaptan, Samsca make sure your physician is aware of any allergies or medications you currently take, if you have hepatic impairment, hyperkalemia, renal impairment, are pregnant, or breastfeeding. Tolvaptan, Samsca use has been associated with rare but serious adverse events such as CNS effects (dizziness, syncope, asthenia), hepatotoxicity, and hypovolemia/dehydration.
What if I miss a dose?
If you miss a dose of medication, try to take it as soon as possible. However, if it is almost time for your next dose, take only that scheduled dose. Do not take double or extra doses.
How should I store this medication?
Keep out of the reach of children at all times. Store at room temperature, 59 to 86° F (15 to 30° C). Protect from light. Keep the container tightly closed. Properly dispose of any unused medication after the expiration date.
What are the possible side effects of using this medication?
Fatigue, dizziness, increased thirst, nausea, xerostomia, diarrhea, polyuria
Note this is not a complete list of side effects, only the most common
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