Zonegran is a medicine that contains the active substance zonisamide. It is available as capsules (white: 25 mg; white and grey: 50 mg; white and red: 100 mg) and as white, circular orodispersible tablets (25, 50, 100 and 300 mg). Orodispersible tablets are tablets that dissolve in the mouth.
|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?|
Zonegran is used as an add-on to existing epilepsy treatment in adults (aged 18 years or over) who have partial seizures (epileptic fits starting in one specific part of the brain). It can be used in patients with and without secondary generalisation (where the seizure subsequently spreads to the whole brain).
The medicine can only be obtained with a prescription.
Zonegran must be added to the patient?s existing treatment. The recommended starting dose is 25 mg twice a day. After one week the dose may be increased to 100 mg a day and then further increased in steps of 100 mg every week, depending on the patient?s response. Zonegran can be given once or twice a day after an appropriate dose is reached. Doses of 300 to 500 mg per day have been shown to be effective, but lower doses may be sufficient in some patients. The maximum daily dose is 500 mg.
Dose increases may need to be made less frequently in patients with liver or kidney problems or those taking certain other medicines. Before stopping Zonegran, the dose should be decreased gradually.
The active substance in Zonegran, zonisamide, is an anti-epileptic. Epileptic fits are caused by abnormal electrical activity in the brain. Zonisamide works by blocking specific pores on the surface of nerve cells called sodium channels and calcium channels. These channels transmit electrical impulses between nerve cells. By blocking these channels, zonisamide prevents the nerve cells from synchronising their activity and prevents abnormal electrical activity spreading through the brain. This reduces the chances of an epileptic fit. Zonegran also acts on the neurotransmitter gamma-aminobutyric acid (GABA, a chemical that allows nerve cells to communicate with each other). This may help to stabilise electrical activity in the brain.
Zonegran capsules have been studied as an add-on to existing treatment in one main study involving 351 patients with partial seizures. The study compared three doses of Zonegran with placebo (a dummy treatment). The doses of Zonegran were increased gradually over six weeks before an 18-week period on a stable dose. The main measure of effectiveness was the change in the frequency of partial seizures between the 12 weeks before treatment started and the 18-week period when a stable dose was used.
The company carried out additional studies to show that the orodispersible tablets produce the same levels of the active substance in the body as the capsules.
Zonegran was more effective than placebo at reducing the frequency of seizures. In the main study, the patients taking 500 mg Zonegran per day had an average reduction in seizure frequency of 51%, compared with 16% in those taking placebo.
The most common side effects with Zonegran (seen in more than 1 patient in 10) are loss of appetite, agitation, irritability, confusion, depression, ataxia (an inability to co-ordinate muscle movements), dizziness, memory impairment, somnolence (sleepiness), diplopia (double vision) and decreased blood bicarbonate levels. Severe rashes have occurred in patients taking Zonegran, including cases of Stevens-Johnson syndrome (a severe, life-threatening type of allergic reaction affecting the skin and mucous membranes). For the full list of all side effects reported with Zonegran, see the Package Leaflet.
Zonegran should not be used in people who may be hypersensitive (allergic) to zonisamide, to any of the other ingredients, or to sulphonamides (such as some antibiotics).