SAMSCA contains tolvaptan, a selective vasopressin V 2 -receptor antagonist in tablets for oral use available in 15 mg or 30 mg strengths. Tolvaptan is (±)-4'-[(7-chloro-2,3,4,5-tetrahydro-5-hydroxy-1 H -1-benzazepin-1-yl) carbonyl]- o -tolu- m -toluidide. The empirical formula is C 26 H 25 ClN 2 O 3. Molecular weight is 448.94. The chemical structure is: Inactive ingredients include corn starch, hydroxypropyl cellulose, lactose monohydrate, low-substituted hydroxypropyl cellulose, magnesium stearate, microcrystalline cellulose, and FD&C Blue No. 2 Aluminum Lake as colorant. Chemical Structure

SAMSCA ® is indicated for the treatment of clinically significant hypervolemic and euvolemic hyponatremia (serum sodium <125 mEq/L or less marked hyponatremia that is symptomatic and has resisted correction with fluid restriction), including patients with heart failure and Syndrome of Inappropriate Antidiuretic Hormone (SIADH). SAMSCA is a selective vasopressin V 2 -receptor antagonist indicated for the treatment of clinically significant hypervolemic and euvolemic hyponatremia [serum sodium <125 mEq/L or less marked hyponatremia that is symptomatic and has resisted correction with fluid restriction], including patients with heart failure and Syndrome of Inappropriate Antidiuretic Hormone (SIADH) Limitations of Use: Patients requiring intervention to raise serum sodium urgently to prevent or to treat serious neurological symptoms should not be treated with SAMSCA It has not been established that SAMSCA provides a symptomatic benefit to patients Limitations of Use Patients requiring intervention to raise serum sodium urgently to prevent or to treat serious neurological symptoms should not be treated with SAMSCA. It has not been established that raising serum sodium with SAMSCA provides a symptomatic benefit to patients.

SAMSCA is available in the following dosage forms and strengths: 15 mg tablets are non-scored, blue, triangular, shallow-convex, debossed with "OTSUKA" and "15" on one side. 30 mg tablets are non-scored, blue, round, shallow-convex, debossed with "OTSUKA" and "30" on one side. Tablets: 15 mg and 30 mg

SAMSCA should be initiated and re-initiated in a hospital The recommended starting dose is 15 mg once daily. Dosage may be increased at intervals ≥24 hr to 30 mg once daily, and to a maximum of 60 mg once daily as needed to raise serum sodium

Recommended Dosage Patients should be in a hospital for initiation and re-initiation of therapy to evaluate the therapeutic response and because too rapid correction of hyponatremia can cause osmotic demyelination resulting in dysarthria, mutism, dysphagia, lethargy, affective changes, spastic quadriparesis, seizures, coma and death. The usual starting dose for SAMSCA is 15 mg administered once daily without regard to meals. Increase the dose to 30 mg once daily, after at least 24 hours, to a maximum of 60 mg once daily, as needed to achieve the desired level of serum sodium. Do not administer SAMSCA for more than 30 days to minimize the risk of liver injury . During initiation and titration, frequently monitor for changes in serum electrolytes and volume. Avoid fluid restriction during the first 24 hours of therapy. Patients receiving SAMSCA should be advised that they can continue ingestion of fluid in response to thirst

Drug Withdrawal Following discontinuation from SAMSCA, patients should be advised to resume fluid restriction and should be monitored for changes in serum sodium and volume status.

Liver injury: Limit treatment duration to 30 days. If hepatic injury is suspected, discontinue SAMSCA. Avoid use in patients with underlying liver disease Dehydration and hypovolemia may require intervention Avoid use with hypertonic saline Avoid use with moderate to strong CYP3A inhibitors Monitor serum potassium in patients with potassium >5 mEq/L or on drugs known to increase potassium Urinary outflow obstruction: Urinary output must be secured 5.1 Too Rapid Correction of Serum Sodium Can Cause Serious Neurologic Sequelae 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, spastic quadriparesis, seizures, coma or death. In susceptible patients, including those with severe malnutrition, alcoholism or advanced liver disease, slower rates of correction may be advisable. In controlled clinical trials in which tolvaptan was administered in titrated doses starting at 15 mg once daily, 7% of tolvaptan-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. Osmotic demyelination syndrome has been reported in association with SAMSCA therapy . 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, 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

Liver Injury Tolvaptan 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. Tolvaptan should not be used to treat ADPKD outside of the FDA-approved risk evaluation and mitigation strategy (REMS) for ADPKD patients . Patients with symptoms that may indicate liver injury, including fatigue, anorexia, right upper abdominal discomfort, dark urine or jaundice should discontinue treatment with SAMSCA. Limit duration of therapy with SAMSCA to 30 days. Avoid use in patients with underlying liver disease, including cirrhosis, because the ability to recover from liver injury may be impaired

Dehydration and Hypovolemia SAMSCA therapy induces copious aquaresis, which is normally partially offset by fluid intake. Dehydration and hypovolemia can occur, especially in potentially volume-depleted patients receiving diuretics or those who are fluid restricted. In multiple-dose, placebo-controlled trials in which 607 hyponatremic patients were treated with tolvaptan, the incidence of dehydration was 3.3% for tolvaptan and 1.5% for placebo-treated patients. In patients receiving SAMSCA who develop medically significant signs or symptoms of hypovolemia, interrupt or discontinue SAMSCA therapy and provide supportive care with careful management of vital signs, fluid balance and electrolytes. Fluid restriction during therapy with SAMSCA may increase the risk of dehydration and hypovolemia. Patients receiving SAMSCA should continue ingestion of fluid in response to thirst

Co-administration with Hypertonic Saline Concomitant use with hypertonic saline is not recommended

Drug Interactions Tolvaptan is a substrate of CYP3A. Moderate to strong CYP3A inhibitors can lead to a marked increase in tolvaptan concentrations . Do not use SAMSCA with strong inhibitors of CYP3A and avoid concomitant use with moderate CYP3A inhibitors

Hyperkalemia or Drugs that Increase Serum Potassium Treatment with tolvaptan is associated with an acute reduction of the extracellular fluid volume which could result in increased serum potassium. Serum potassium levels should be monitored after initiation of tolvaptan treatment in patients with a serum potassium >5 mEq/L as well as those who are receiving drugs known to increase serum potassium levels

Acute Urinary Retention with Outflow Obstruction Patients with partial obstruction of urinary outflow, for example, patients with prostatic hypertrophy or impairment of micturition, have an increased risk of developing acute retention. Do not administer tolvaptan in patients with uncorrected urinary outflow obstruction.

Avoid concomitant use with: Moderate CYP3A inhibitors Strong CYP3A inducers V 2 -receptor antagonists Monitor serum potassium during concomitant therapy with: Angiotensin receptor blockers Angiotensin converting enzyme inhibitors Potassium sparing diuretics 7.1 CYP3A Inhibitors and Inducers Strong CYP3A Inhibitors Tolvaptan's AUC was 5.4 times as large and C max was 3.5 times as large after co-administration of tolvaptan and 200 mg ketoconazole . Larger doses of the strong CYP3A inhibitor would be expected to produce larger increases in tolvaptan exposure. Concomitant use of tolvaptan with strong CYP3A inhibitors is contraindicated . Moderate CYP3A Inhibitors A substantial increase in the exposure to tolvaptan would be expected when SAMSCA is co-administered with moderate CYP3A inhibitors. Avoid co-administration of SAMSCA with moderate CYP3A inhibitors . Patients should avoid grapefruit juice beverages while taking SAMSCA . Strong CYP3A Inducers Co-administration of SAMSCA with strong CYP3A inducers reduces exposure to SAMSCA . Avoid concomitant use of SAMSCA with strong CYP3A inducers

Angiotensin Receptor Blockers, Angiotensin Converting Enzyme Inhibitors and Potassium Sparing Diuretics Although specific interaction studies were not performed, in clinical studies, tolvaptan was used concomitantly with beta-blockers, angiotensin receptor blockers, angiotensin converting enzyme inhibitors and potassium sparing diuretics. Adverse reactions of hyperkalemia were approximately 1 to 2% higher when tolvaptan was administered with angiotensin receptor blockers, angiotensin converting enzyme inhibitors and potassium sparing diuretics compared to administration of these medications with placebo. Serum potassium levels should be monitored during concomitant drug therapy

V 2 -Receptor Agonist As a V 2 -receptor antagonist, tolvaptan may interfere with the V 2 -agonist activity of desmopressin (dDAVP). Avoid concomitant use of SAMSCA with a V 2 -agonist.