Indications
Zonisamide is an anti-seizure medicine used to treat focal (partial) seizures in adults, with or without spreading to the whole brain (secondary generalisation). It may be used alone in newly diagnosed adults or added to other anti-seizure medicines in adults and children over 6 years.
How It Works
Zonisamide blocks sodium and T-type calcium channels in nerve cells, which stops nerve cells from firing too quickly and repeatedly. It also has weak carbonic anhydrase-blocking action. Together these effects reduce the abnormal electrical activity in the brain that causes seizures.
Dosage and Administration
Take exactly as prescribed. The doctor starts with a low dose and increases it slowly over several weeks to reduce side effects; the final dose depends on response and on other medicines you take. Swallow capsules whole with water, with or without food, once or twice a day as directed. Drink plenty of fluids every day. Do not stop suddenly, as seizures may return; the dose should be reduced gradually.
Interactions
Carbamazepine, Phenytoin, Phenobarbital and Rifampicin can lower Zonisamide levels. Using it with other carbonic anhydrase inhibitors such as Topiramate or Acetazolamide increases the risk of kidney stones and acidosis. Anticholinergic medicines may add to the risk of overheating. Alcohol and sedatives can increase drowsiness.
Contraindications
- Allergy to Zonisamide or to sulfonamide (sulfa) medicines, as Zonisamide is a sulfonamide.
Side Effects
Common side effects include drowsiness, dizziness, loss of appetite, weight loss, nausea, irritability, trouble concentrating or remembering, double vision and tiredness. Kidney stones can occur.
Get urgent medical help for a skin rash (rarely it can become life threatening), fever with sore throat or unusual bruising, sudden back or side pain with blood in the urine (kidney stones), reduced sweating with high body temperature, especially in children, fast or deep breathing, sudden eye pain or blurred vision, or thoughts of self-harm or suicide.
Pregnancy and Lactation
Zonisamide may harm the unborn baby. Women who could become pregnant should use effective contraception during treatment and for one month after stopping, and should plan pregnancy with their doctor; do not stop it suddenly. It passes into breast milk; breastfeeding is not recommended during treatment and for one month after stopping.
Precautions and Warnings
Tell your doctor about kidney or liver disease, a history of kidney stones, depression, or low body weight. Children are at risk of overheating and dehydration in hot weather. Blood tests for bicarbonate (acid balance) may be done. It can cause drowsiness, so take care when driving.
Overdose
Overdose may cause severe drowsiness, slow heartbeat, low blood pressure, breathing problems and coma. Seek emergency medical help immediately and take the pack with you.
Therapeutic Class
Antiepileptic (anticonvulsant); sulfonamide derivative.
Storage
Store below 30°C in a dry place, away from light and out of the reach of children.
Prepared by the Oshud Alo team from standard drug references. For information only; always follow your doctor's advice.