Samsca

Samsca (tolvaptan) is a selective vasopressin V2-receptor antagonist indicated for the treatment of clinically significant hypervolemic and euvolemic hyponatremia. It is specifically designed to address serum sodium imbalances in patients with conditions such as syndrome of inappropriate antidiuretic hormone secretion (SIADH), heart failure, and cirrhosis. By promoting aquaresis—the electrolyte-sparing excretion of free water—Samsca offers a targeted mechanism to raise serum sodium concentrations in a controlled manner, aiding in the restoration of electrolyte homeostasis under careful medical supervision.

Features

• Contains tolvaptan, a selective vasopressin V2-receptor antagonist
• Available in 15 mg and 30 mg oral tablets
• Promotes aquaresis—exclusive water excretion without substantial sodium or potassium loss
• Initiation and dose titration require inpatient setting due to need for frequent serum sodium monitoring
• Not indicated for use in patients with hypovolemic hyponatremia
• Requires avoidance of concomitant use with strong CYP 3A inhibitors

Benefits

• Effectively increases low serum sodium levels in appropriate patient populations
• Provides a mechanism for controlled correction of hyponatremia, reducing risks of osmotic demyelination
• Helps alleviate symptoms associated with hyponatremia, such as confusion, headache, and nausea
• Supports management of chronic hyponatremia in conditions like SIADH, heart failure, and cirrhosis
• Contributes to stabilized electrolyte balance under medical supervision
• May reduce hospital length of stay through efficient sodium correction in monitored settings

Common use

Samsca is commonly used in hospitalized patients with euvolemic or hypervolemic hyponatremia. It is frequently prescribed for individuals with syndrome of inappropriate antidiuretic hormone (SIADH), congestive heart failure, or liver cirrhosis with ascites, where water retention contributes to dilutional hyponatremia. The medication is initiated in a controlled environment where serum sodium and volume status can be closely monitored to ensure safe correction rates and avoid overly rapid sodium elevation.

Dosage and direction

Initiate treatment with 15 mg orally once daily. Dose may be increased to 30 mg once daily after at least 24 hours, to a maximum of 60 mg once daily, as needed to achieve desired serum sodium concentration. Administer with or without food. Continue treatment until no longer clinically warranted. Monitoring of serum sodium and volume status is essential, particularly during initiation and titration. Avoid fluid restriction during the first 24 hours of therapy.

Precautions

Samsca should be used with caution in patients with renal impairment, as there is limited experience in those with CrCl <10 mL/min or requiring dialysis. Hepatic impairment requires careful consideration; avoid use in patients with underlying liver disease. Monitor for signs of dehydration or hypovolemia. Patients must be able to sense and respond to thirst. Not recommended for use in patients with inability to adequately intake water. Discontinue therapy if significant liver injury is suspected.

Contraindications

Samsca is contraindicated in patients with hypovolemic hyponatremia. Concomitant use with strong CYP 3A inhibitors (e.g., ketoconazole, clarithromycin) is contraindicated. Use is contraindicated in patients with urgent need to raise serum sodium acutely, anuria, or inability to sense or respond to thirst. Should not be used in patients with known hypersensitivity to tolvaptan or any component of the formulation.

Possible side effects

Common adverse reactions include thirst, dry mouth, asthenia, constipation, pollakiuria or polyuria, and hyperglycemia. Serious side effects may include overly rapid correction of sodium leading to osmotic demyelination, dehydration, hypovolemia, and gastrointestinal bleeding in cirrhotic patients. Liver enzyme elevations and signs of hepatotoxicity have been reported. Monitor for signs of excessive aquaresis such as dizziness, syncope, or orthostatic hypotension.

Drug interaction

Strong CYP 3A inhibitors (e.g., ketoconazole, itraconazole, clarithromycin) significantly increase tolvaptan exposure and are contraindicated. Moderate CYP 3A inhibitors (e.g., erythromycin, fluconazole, aprepitant) and P-gp inhibitors may increase tolvaptan concentrations; consider dose reduction. CYP 3A inducers (e.g., rifampin, carbamazepine) may decrease tolvaptan efficacy. Use with caution with medications that affect serum sodium or potassium levels.

Missed dose

If a dose is missed, instruct the patient to take it as soon as remembered on the same day. Do not take two doses on the same day to make up for a missed dose. Resume the regular dosing schedule the following day. Patients should not double the dose. If unsure, patients should contact their healthcare provider for guidance.

Overdose

Overdose may lead to profound water loss, dehydration, hypovolemia, and hypernatremia. Signs and symptoms may include excessive thirst, dry mouth, dizziness, weakness, hypotension, and tachycardia. Treatment involves discontinuation of Samsca, careful water replacement, and symptomatic management of volume and electrolyte abnormalities. Hemodialysis is not expected to enhance elimination. Contact Poison Control for latest guidance.

Storage

Store at room temperature between 20°C to 25°C (68°F to 77°F); excursions permitted between 15°C to 30°C (59°F to 86°F). Keep in original container with desiccant to protect from moisture. Keep out of reach of children and pets. Do not use beyond the expiration date printed on the packaging.

Disclaimer

This information is for educational purposes and does not replace professional medical advice, diagnosis, or treatment. Always consult with a qualified healthcare provider before starting or changing any medication regimen. Individual patient responses may vary. Serious side effects should be reported to a healthcare professional immediately.

Reviews

Clinical trials demonstrate Samsca’s efficacy in raising serum sodium levels in hyponatremic patients. In the SALT studies, tolvaptan significantly improved serum sodium concentrations compared to placebo at day 4 and day 30. Many clinicians report successful use in appropriate patients with careful monitoring. Some note challenges with thirst and urinary frequency as common but manageable side effects. Overall, it is regarded as a valuable option for controlled correction of hyponatremia in monitored settings.