Active Substance: zonisamide
Common Name: zonisamide
ATC Code: N03AX15
Marketing Authorisation Holder: Eisai Ltd.
Active Substance: zonisamide
Authorisation Date: 2005-03-10
Therapeutic Area: Epilepsies, Partial
Pharmacotherapeutic Group: Anti-epileptics
Zonegran is indicated as:
- monotherapy in the treatment of partial seizures, with or without secondary generalisation, in adults with newly diagnosed epilepsy;
- adjunctive therapy in the treatment of partial seizures, with or without secondary generalisation in adult patients.
What is Zonegran?
Zonegran is a medicine that contains the active substance zonisamide. It is available as capsules (25, 50 and 100 mg) and tablets (25, 50, 100 and 300 mg).
What is Zonegran used for?
Zonegran is used to treat adults with partial seizures (epileptic fits starting in one part of the brain), including those who have secondary generalisation (where the seizure subsequently spreads to the whole brain).
Zonegran is used either on its own in newly diagnosed patients or as an ‘add-on’ therapy in patients already receiving other anti-epilepsy medicines.
The medicine can only be obtained with a prescription.
How is Zonegran used?
When used on its own in newly diagnosed patients, the recommended starting dose is 100 mg once a day for two weeks, which may be increased by 100 mg at intervals of two weeks. The usual maintenance dose is 300 mg a day.
When Zonegran is used as an ‘add-on’ to 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. The usual maintenance dose is between 300 and 500 mg a day.
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.
How does Zonegran work?
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.
How has Zonegran been studied?
Zonegran used on its own was compared with carbamazepine, another anti-epileptic medicine, in a main study involving 583 patients newly diagnosed with partial epilepsy. The main measure of effectiveness was the proportion of patients who were seizure-free for a period of six months.
Another main study involving 351 patients looked at Zonegran as an add-on to existing treatment. This study compared Zonegran with placebo (a dummy treatment). 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.
What benefit has Zonegran shown during the studies?
Zonegran used on its own was shown to be beneficial in patients with partial seizures: 69.4% of patients on Zonegran were seizure-free for six months. The percentage of patients on carbamazepine who were seizure-free for six months was 74.7%.
Zonegran was more effective than placebo at reducing the frequency of seizures when used as an ‘add-on’ to existing treatment. Patients taking 500 mg Zonegran per day had an average reduction in seizure frequency of 51%, compared with 16% in those taking placebo.
What is the risk associated with Zonegran?
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 coordinate 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 must not be used in people who are hypersensitive (allergic) to zonisamide, to any of the other ingredients, or to sulphonamides (such as some antibiotics).
Why has Zonegran been approved?
The CHMP decided that Zonegran’s benefits are greater than its risks and recommended that it be given marketing authorisation.
Other information about Zonegran
The European Commission granted a marketing authorisation valid throughout the European Union for Zonegran on 10 March 2005.
For more information about treatment with Zonegran, read the package leaflet (also part of the EPAR) or contact your doctor or pharmacist.
Source: European Medicines Agency
Disclaimer: Every effort has been made to ensure that the information provided here is accurate, up-to-date, and complete, but no guarantee is made to that effect. Drug information contained herein may be time sensitive. This information has been compiled for use by healthcare practitioners and consumers in the United States. The absence of a warning for a given drug or drug combination in no way should be construed to indicate that the drug or drug combination is safe, effective or appropriate for any given patient. If you have questions about the drugs you are taking, check with your doctor, nurse or pharmacist.