Overview of Zonisamide
for Canines and Felines
- Zonisamide is a drug used to treat seizures in dogs. Previously used in conjunction with other medications, it is now used as a primary drug for seizure control. Zonisamide belongs to a general class of drugs known as anticonvulsants. Other related drugs in this class include diazepam, levetiracetam, potassium bromide, and phenobarbital.
- The mechanism of action of zonisamide is not well understood, but is thought to block sodium channels in the brain which in turn stabilizes neuronal membranes. This depresses the excitability of nerves within the brain and results in reduced seizures.
- Zonisamide is considered a prescription drug and can only be obtained from a veterinarian or by prescription from a veterinarian.
- This drug is not approved for use in animals by the Food and Drug Administration but it is prescribed legally by veterinarians as an extra-label drug.
Brand Names and Other Names
- Human formulations: Zonegran® (Eisai) and in generic formulations
- Veterinary formulations: None
Uses of Zonisamide
for Dogs and Cats
Zonisamide is used to treat seizure disorders in dogs as either monotherapy (single drug) or part of combination therapy with other anticonvulsant drugs.
Precautions and Side Effects
- While generally safe and effective when prescribed by a veterinarian, Zonisamide can cause side effects in some animals.
- This drug should not be used in animals with a known hypersensitivity or allergy. IMPORTANT: Zonisamide is a sulfonamide drug and should not be used in patients allergic to sulfa drugs.
- Zonisamide should be used with caution in older animals and animals with kidney impairment.
- This drug may interact with other medications. Consult with your veterinarian to determine if other drugs your pet is receiving could interact with zonisamide.
- One of the most common side effects of zonisamide is sedation, which is typically transient. Nausea, vomiting, and lack of appetite are also common side effects.
How Zonisamide Is Supplied
Zonisamide (Zonegran®) is available in capsules in 25, 50, and 100 mg dosages.
Dosing Information for Zonisamide
for Dogs and Cats
- Medication should never be administered without first consulting your veterinarian.
- In dogs, zonisamide is started at 2.5 to 5 mg per pound (5 to 10 mg/kg) twice daily.
- In cats, zonisamide is started at 2.5 mg per pound (5 mg/kg) twice daily. Alternatively, some cats can receive higher doses such as 2.5 to 5 mg per pound (5 to 10 mg/kg) once daily.
- Increases in dose may be required to control seizures.
- Therapeutic blood monitoring is not routinely recommended. When performed, the suggested therapeutic range is 10–40 µg/mL based on limited data.
- Do not stop administering this drug abruptly or rebound seizures may occur.
- The duration of administration depends on the condition being treated, response to the medication, and the development of any adverse effects. Be certain to administer the complete prescription to your pet unless specifically directed otherwise by your veterinarian. Even if your pet feels better, the entire treatment plan should be completed to prevent relapse or the development of resistance