Zonisamide (Zonegran®)

Introduction

Zonisamide is an anticonvulsant medication designed to reduce the frequency and severity of seizures in pets. While no seizure medication can guarantee complete seizure freedom, the goal is to significantly reduce their occurrence and intensity.

Skeletal formula of an anticonvulsant medication zonisamide

Missed doses and Changing medications

It is very important to give this medication on schedule. Make a note of when you need refills, and try to get them as early as is practical. Set a timer on your watch or phone to help remind you to give the medication on schedule. This medication is usually given twice a day, and may be given with or without food.

If you miss a single dose of zonisamide, give it as soon as you remember, even if it is time for the next dose. Stopping this medication suddenly can cause seizures.
In general, seizure medications should be tapered before stopping. Exceptions to this include pet’s on very short courses of medications, and pet’s experiencing dangerous side effects. As always, please contact your medical team before making changes to your pet’s medication.

Monitoring and Lab work

Regular veterinary visits are recommended at least twice a year to monitor your pet’s response to Zonisamide. A complete blood count (CBC), chemistry panel, and urinalysis should be performed annually. If collecting a urine sample from home on the day of the appointment, use a clean disposable container to catch the sample as close to the appointment time as possible. Otherwise, try to prevent your pet from urinating right before the visit to help with collection at the time of the visit.

Potential Side effects

While many pets tolerate Zonisamide well, some side effects may occur:

Sedation and Incoordination: Pets may appear sleepy or uncoordinated, particularly during the initial adjustment period. Keep them safe from potential hazards during this time.
Gastrointestinal Issues: Inappetence and vomiting can occur. If your pet’s appetite significantly decreases, an alternative medication may be necessary.
Urinary pH Changes: Zonisamide can alter the pH of your pet’s urine, potentially leading to urinary stones. This is monitored through annual urinalysis and can be managed with diet changes or medication adjustment.
Liver and Blood Cell Changes: Liver dysfunction and alterations in blood cell counts are rare but monitored through annual blood tests.
Behavioral Changes: Watch for any increase in restlessness or aggression.
Dermatological Issues: Itching or skin lesions are rare. If you notice any changes in your pet’s skin, contact your veterinary team immediately.