Samsca Warnings

Too rapid correction of serum sodium can cause serious neurologic sequelae: SAMSCA should be initiated and re-initiated in patients only in a hospital where serum sodium can be monitored closely.
Patients should be frequently monitored for their serum sodium and volume status after administration of SAMSCA because SAMSCA can cause too rapid increase of serum sodium.
Osmotic demyelination syndrome is a risk associated with too rapid correction of hyponatremia (e.g., > 12 mEq/L/24 hours). Osmotic demyelination results in dysarthria, mutism, dysphagia, lethargy, affective changes or spastic quadriparesis, seizures, coma and death. In susceptible patients, including those with hypoxia, severe malnutrition, alcoholism or advanced liver disease, slower rates of correction may be advisable.
Sodium correction that exceeds 6 mEq/L during the first 6 hours of administration or 8 mEq/L during the first 6 - 12 hours may be too rapid; in such patients close monitoring of serum sodium and administration of hypotonic fluid are recommended. SAMSCA treatment should be interrupted or discontinued and followed by administration of hypotonic fluid if the increase in serum sodium is too rapid (i.e. if it exceeds 12 mEq/L in 24 hours, or 18 mEq/L in 48 hours).
In controlled clinical trials in which SAMSCA was administered in titrated doses starting at 15 mg once daily, 7% of SAMSCA treated subjects with a serum sodium < 130 mEq/L had an increase in serum sodium greater than 8 mEq/L at approximately 8 hours and 2% had an increase greater than 12 mEq/L at 24 hours. Approximately 1% of placebo-treated subjects with a serum sodium < 130 mEq/L had a rise greater than 8 mEq/L at 8 hours and no patient had a rise greater than 12 mEq/L/24 hours.
Patients treated with SAMSCA should be monitored to assess serum sodium concentrations and neurologic status, especially during initiation and after titration. Subjects with SIADH or very low baseline serum sodium concentrations may be at greater risk for too-rapid correction of serum sodium. In patients receiving SAMSCA who develop too rapid a rise in serum sodium (>12 mEq/L/24 hours), discontinue or interrupt treatment with SAMSCA and consider administration of hypotonic fluid. Fluid restriction during the first 24 hours of therapy with SAMSCA may increase the likelihood of overly-rapid correction of serum sodium, and should generally be avoided. Co-administration of diuretics also increases the risk of too rapid correction of serum sodium and such patients should undergo close monitoring of serum sodium.
Co-administration of SAMSCA with any other treatment for hyponatremia, and medications that increase serum sodium concentration is not recommended. These patients may be at higher risk for developing rapid correction of serum sodium during the first 1-2 days of treatment due to potential additive effects. Therefore, if co-administration is essential then these patients should be managed very cautiously.
Liver Injury: SAMSCA can cause serious and potentially fatal liver injury. In placebo-controlled studies and an open-label extension study of chronically administered tolvaptan in patients with ADPKD, cases of serious liver injury attributed to tolvaptan, generally occurring during the first 18 months of therapy, were observed. In postmarketing experience with tolvaptan in ADPKD, acute injury resulting in liver failure requiring liver transplantation has been reported. SAMSCA should not be used to treat ADPKD.
Limit duration of therapy with SAMSCA to 30 days for treatment of hyponatremia. Avoid use in patients with underlying liver disease, including cirrhosis, because the ability to recover from liver injury may be impaired.
Liver function tests must be promptly performed in patients taking SAMSCA who report symptoms that may indicate liver injury, including fatigue, anorexia, right upper abdominal discomfort, dark urine or jaundice. If liver injury is suspected, SAMSCA must be promptly discontinued, appropriate treatment has to be instituted, and investigations have to be performed to determine the probable cause. SAMSCA must not be re-initiated in patients unless the cause for the observed liver injury is definitively established to be unrelated to treatment with SAMSCA.
For the treatment of volume overload in heart failure, liver function tests should be performed prior to initiation of SAMSCA and frequently at least for the first 2 weeks of treatment.
Hypernatremia: Hemoconcentration associated with rapid diuresis may induce hypernatremia, possibly accompanied by consciousness disturbance. In patients being treated with SAMSCA, fluid intake, urine volume, serum sodium level, and the occurrence of clinical symptoms such as thirst and dehydration should be carefully monitored. If clinical symptoms such as persistent thirst and dehydration are observed, SAMSCA should be discontinued or the dosage reduced and appropriate measures such as fluid replenishment, including fluid therapy, should be taken in accordance with the symptoms. If serum sodium level is increased above the normal range, administration of SAMSCA should be discontinued immediately and appropriate measures such as fluid replenishment, including fluid therapy, should be taken.