SAMSCA® (tolvaptan) is the first-and-only oral vasopressin V2-receptor antagonist that increases serum sodium concentration through free water clearance
- Proven effective for clinically significant hypervolemic and euvolemic hyponatremia
- Represents an important treatment option for clinically significant dilutional hyponatremia1,2
- In healthy subjects, after a single 60-mg dose of SAMSCA, free water clearance and serum sodium increase occurred within 2 to 4 hours post-dose
![Mechanism of Action video placeholder](sites/g/files/qhldwo5351/themes/site/themes/custom/samsca_hcp2/images/samsca-moa-poster.png)
Targeted MOA: Vasopressin V2-receptor antagonism
![SAMSCA blocks vasopressin](/sites/g/files/qhldwo5351/files/2017-12/icon-moa-1.jpg)
1. SAMSCA blocks vasopressin SAMSCA selectively blocks the binding of vasopressin to the V2-receptors in the renal collecting ducts.2-4
Increases free water clearance
![Aquaporin Decrease](/sites/g/files/qhldwo5351/files/2017-12/icon-moa-2.jpg)
2. Decreased expression of aquaporin Inhibition of vasopressin binding to the V2-receptor leads to decreased expression and removal of aquaporin-2 from the luminal membrane.3,5
![Water Absorption Decrease](/sites/g/files/qhldwo5351/files/2017-12/icon-moa-3.jpg)
3. Decreased water reabsorption V2-receptor blockade results in decreased water reabsorption by the kidney.3-5
Onset of aquaretic effect
![Aquaresis Increase](/sites/g/files/qhldwo5351/files/2017-12/icon-moa-4.png)
4. Diuresis vs aquaresis Diuresis and aquaresis are different. Diuresis is an increase in overall urine production. SAMSCA provides aquaresis, or excretion water without clinically significant electrolyte loss.6
![Increased Serum Sodium And Urine Osmolality](/sites/g/files/qhldwo5351/files/2017-12/icon-moa-5.jpg)
5. Serum sodium concentration and urine osmolality Aquaresis results in increased serum sodium concentration and decreased urine osmolality.
![Sodium And Potassium Excretion](/sites/g/files/qhldwo5351/files/2017-12/icon-moa-6.jpg)
6. Sodium and potassium excretion This process does not, however, result in significant change in urinary excretion of sodium or potassium, nor does it result in increased plasma potassium.