What is Samsca?
Samsca is a medicine that contains the active substance tolvaptan. It is available as blue tablets (triangular: 15 mg; round: 30 mg).
What is Samsca used for?
Samsca is used to treat adults with hyponatremia (exceptionally low levels of sodium in the blood) caused by a condition called "syndrome of inappropriate antidiuretic hormone secretion" (SIADH). SIADH occurs when there is an excessive amount of a hormone called "antidiuretic hormone" or "vasopressin", which reduces the leakage of urine by retaining water in the blood. This results in a dilution of the blood, and a consequent lowering of the sodium level.
The medicine can only be obtained with a prescription.
How is Samsca used?
Treatment with Samsca should be started in the hospital so that healthcare professionals can determine the most appropriate dosage and monitor the patient's blood sodium level and blood volume.
The starting dose is 15 mg once a day. It can be increased to a maximum of 60 mg once a day to reach an appropriate level of sodium and blood volume. The tablets should be swallowed whole with a glass of water. They cannot be taken with grapefruit juice.
How does Samsca work?
People with SIADH contain a quantity of vasopressin, which leads to a decrease in urine production and a dilution of blood. The active substance in Samsca, tolvaptan, is a vasopressin 2 receptor antagonist. This means that it blocks a type of receptor (a protein) to which the hormone vasopressin normally attaches. By blocking this receptor, Samsca prevents vasopressin from having its effect. This leads to an increase in urine production, decreasing the amount of water and increasing the level of sodium in the blood.
What studies have been carried out on Samsca?
The effects of Samsca were first tested in experimental models before being studied in humans.
Samsca has been compared with a placebo (a dummy treatment) in two main studies involving 424 adults with low sodium levels caused by SIADH and other conditions such as liver and heart problems. The main measure of effectiveness was based on the change in the
amount of sodium in the blood within the first 30 days of treatment. The study also specifically examined the effect of treatment in different disease groups.
What benefit has Samsca shown during the studies?
Samsca was more effective than placebo in increasing blood sodium levels in all diseases, but also in patients with SIADH compared to those with liver or heart problems.
At the beginning of the study sodium levels amounted to approximately 129 mmol / l. In patients with SIADH, levels were increased on average by 4.8 mmol / l on the fourth day in those who were treated with Samsca, compared to 0.2 mmol / l in those who were treated with placebo. By day 30, sodium had increased on average by 7.4 mmol / l in patients who were treated with Samsca, compared with 1.5 mmol / l in patients who were treated with placebo.
What is the risk associated with Samsca?
Side effects that may occur more commonly with Samsca (observed in more than 1
patient out of 10) are thirsty and nausea. For the full list of all side effects reported with Samsca, see the Package Leaflet.
Samsca should not be used in people who may be hypersensitive (allergic) to tolvaptan or any of the other ingredients. It must not be used in patients with anuria (inability to urinate), very limited blood volume, low blood sodium levels with limited blood volumes, hypernatremia (excessively high levels of sodium in the blood) or in patients who cannot feel the thirst. It must also be used in pregnant or breast-feeding women.
Why has Samsca been approved?
The Committee for Medicinal Products for Human Use (CHMP) decided that Samsca's benefits are greater than its risks for the treatment of adult patients with hyponatremia secondary to SIADH. The Committee recommended that Samsca be given marketing authorization.
More information about Samsca:
On 3 August 2009, the European Commission granted Samsca a marketing authorization valid throughout the European Union to Otuska Pharmaceutical Europe Ltd.
For the full EPAR for Samsca, click here.
Last update of this summary: 06-2009.
