Author: Glaxo Group Ltd.


Long information

What is it?

Trobalt is a medicine that contains the active substance retigabine. It is available as tablets (purple round: 50 mg; green round: 100 mg; yellow oblong: 200 mg; green oblong: 300 mg; purple oblong: 400 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?

What is it used for?

Trobalt is used to treat adults with partial-onset seizures (epileptic fits) with or without secondary generalisation. This is a type of epilepsy where too much electrical activity in one part of the brain causes symptoms such as sudden, jerky movements of one part of the body, distorted hearing, sense of smell or vision, numbness or a sudden sense of fear. Secondary generalisation occurs when the excessive electrical activity subsequently reaches the whole brain. Trobalt must only be used as an ?add-on? to other anti-epileptic medicines.

The medicine can only be obtained with a prescription.

How is it used?

Treatment with Trobalt starts with one 100 mg tablet three times a day for one week; the dose is then increased weekly by 50 mg per dose according to the patient?s response. The recommended maintenance dose is between 600 mg a day and a maximum of 1,200 mg a day.

Lower doses should be used in older patients and in patients with moderate or severe liver or kidney problems. For more information on how to use Trobalt, including detailed recommendations for different patients groups, see the summary of product characteristics (also part of the EPAR).

How does it work?

The active substance in Trobalt, retigabine, is an anti-epileptic medicine. Epilepsy is caused by excessive electrical activity in the nerve cells of the brain. Trobalt has an effect on the potassium channels located on the nerve cells of the brain. These are pores that let potassium move in and out of the cell and play a role in terminating electrical impulses. Trobalt acts by keeping the potassium channels open. This will stop further transmission of electrical impulses thereby preventing epileptic seizures.

How has it been studied?

The effects of Trobalt were first tested in experimental models before being studied in humans.

Trobalt has been compared with placebo (a dummy treatment) in three main studies involving a total of 1,244 patients whose seizures were not adequately controlled with other anti-epileptic medicines. Trobalt at a maintenance dose of 600, 900 or 1,200 mg a day or placebo was taken for 8 weeks in the first study and 12 weeks in the other two studies. In the first study, the main measure of effectiveness was the change in the number of seizures per month. In the other two studies, the main measure of effectiveness was the number of patients whose number of seizures was at least halved.

What benefits has it shown during the studies?

Trobalt was more effective than placebo in reducing the number of seizures. In the first study, Trobalt at 900 mg a day and 1,200 mg a day was more effective than placebo and reduced the number of seizures per month by 29% and 35% respectively. This compared with a reduction of 13% in the placebo group. The effect of Trobalt at 600 mg a day was inconclusive in this study. In the second study, seizures were at least halved in 39% (61 out of 158 patients) of the patients on 600 mg Trobalt a day and in 47% (70 out of 149 patients) of the patients on 900 mg a day, compared with 19% (31 out of 164) of the patients on placebo. In the third study, seizures were at least halved in 56% (66 out of 119 patients) of the patients taking 1,200 mg Trobalt a day, compared with 23% (31 out of 137) of the patients on placebo.

What is the risk associated?

The most common side effects with Trobalt (seen in more than 1 patient in 10) are dizziness, somnolence (sleepiness) and fatigue (tiredness). For the full list of all side effects reported with Trobalt, see the package leaflet.

Trobalt should not be used in people who may be hypersensitive (allergic) to retigabine or any of the other ingredients.

Why has it been approved?

The CHMP decided that benefits of Trobalt are greater than its risks and recommended that it be given marketing authorisation.

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