Samsca is a medicine that contains the active substance tolvaptan. It is available as blue tablets (triangular: 15 mg; round: 30 mg).
|Table of Contents|
|What is it used for?|
|How is it used?|
|How does it work?|
|How has it been studied?|
|What benefits has it shown during the studies?|
|What is the risk associated?|
|Why has it been approved?|
Samsca is used to treat adults with hyponatraemia (abnormally 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 urine output by retaining water in the blood. This results in the blood becoming diluted, lowering the level of sodium.
The medicine can only be obtained with a prescription.
Treatment with Samsca should be started in hospital so that healthcare professionals can determine the most appropriate dose and monitor the patient?s level of blood sodium and blood volume. The starting dose is 15 mg once a day. This may be increased to a maximum of 60 mg once a day to achieve an appropriate level of blood sodium and blood volume.
The tablets should be swallowed whole with a glass of water. They should not be taken with grapefruit juice.
People with SIADH have an amount of vasopressin, leading to decreased urine production and dilution of the blood. The active substance in Samsca, tolvaptan, is a ?vasopressin-2 receptor antagonist?. This means that it blocks one type of receptor (a protein) to which the hormone vasopressin normally attaches itself. By blocking this receptor, Samsca prevents vasopressin from having its effect. This leads to an increase in urine production, decreasing the amount of water in the blood and increasing the blood sodium level.
The effects of Samsca were first tested in experimental models before being studied in humans. Samsca was compared with 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 over the first 30 days of treatment. The study also looked specifically at effect of treatment in the different disease groups.
Samsca was more effective than placebo at increasing sodium levels in the blood in all diseases, but Samsca was more effective in patients with SIADH than with liver or heart problems. Sodium levels were around 129 mmol/l at the start of the study. In patients with SIADH, the levels had increased by an average of 4.8 mmol/l by day 4 in those who took Samsca, compared with 0.2 mmol/l in those who took placebo. By day 30, sodium had increased by an average of 7.4 mmol/l in patients who took Samsca, compared with 1.5 mmol/l in patients receiving placebo.
The most common side effects with Samsca (seen in more than 1 patient in 10) are thirst and nausea (feeling sick). 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 (an inability to pass urine), very low blood volume, low blood sodium levels with low blood volume, hypernatremia (abnormally high levels of sodium in the blood) or in patients who cannot perceive thirst. It must also not be used in women who are pregnant or breast-feeding.