ZONISADE (zonisamide oral suspension) is chemically classified as a sulfonamide. The active ingredient is zonisamide, 1,2-benzisoxazole-3-methanesulfonamide. The empirical formula is C 8 H 8 N 2 O 3 S with a molecular weight of 212.23. Zonisamide is a white powder, pKa = 10.2, and is moderately soluble in water (0.80 mg/mL) and 0.1 N HCl (0.50 mg/mL). The chemical structure is: ZONISADE is an aqueous white to off-white liquid oral suspension. Each mL contains 20 mg of zonisamide. Inactive ingredients include carboxymethylcellulose sodium, citric acid monohydrate, microcrystalline cellulose, purified water, sodium benzoate, strawberry flavor, sucralose, trisodium citrate dihydrate, and xanthan gum. Chemical Structure

What kind of drug is zonisamide?

The FDA classifies zonisamide as an anti-epileptic agent. Anti-epileptic (anticonvulsant) drugs calm the abnormal, excessive electrical activity that triggers seizures. They do this by stabilizing overactive sodium or calcium channels in nerve cells, boosting the brain's natural calming chemical GABA, or dampening excitatory signals, which makes nerves less likely to fire uncontrollably. If you are checking whether it is safe to combine with something else, the class is what matters — two drugs from the same class usually should not be stacked.

Can you take zonisamide with other medicines?

It depends on the medicine. We check it against the FDA labels rather than guessing: our interaction checker searches each drug's own label for the other and quotes what it says, naming the section it came from. Run zonisamide against whatever else you take — and remember that a label not naming a drug is not the same as that combination being safe.

What brand names is zonisamide sold under?

We track 2 zonisamide-containing products in the U.S.: Zonisade and Zonegran. They are the same active ingredient; they differ in form, manufacturer, price and FDA recall record.

What forms does zonisamide come in?

Across the brands we track, zonisamide is currently marketed as suspension and capsule, per the FDA's National Drug Code Directory. Each form is dosed differently — follow the label for the exact product you were prescribed.

Is there a generic zonisamide?

We do not currently list a generic-labelled zonisamide product. That does not always mean none exists — it means none appears under a generic name in the FDA data we track. Ask your pharmacist.

Zonisamide: uses, dosing, side effects & brands

Zonisamide is an anti-epileptic agent sold in the U.S. under 2 brand and generic names, for partial epilepsies. Below: what the FDA label says, every product that contains it, what the pills look like, and its recall record.

By the pharmaranks editorial teamReviewed against the FDA (openFDA label, NDC Directory & Enforcement) sourcesHow we research

Key facts

Drug class: Anti-Epileptic Agent
Treats: Partial Epilepsies
Available as: Suspension · Capsule
Sold as: 2 products — Zonisade and Zonegran
Prescription?: Prescription only
Generic available?: Not in our catalog
Typical price: about $3 for a 30-count supply

How zonisamide is dosed

From the FDA label for Zonisade (application NDA214273). Other zonisamide products — different forms, different strengths — are dosed differently. Follow the label for the one you were prescribed.

The recommended initial dosage of ZONISADE is 100 mg daily. The dosage may be increased by 100 mg daily every two weeks, based on clinical response and tolerability, to 400 mg daily. Patients who are tolerating ZONISADE at 400 mg daily and require further reduction of seizures may be increased up to a maximum dosage of 600 mg daily ( 2.2 ). • ZONISADE is given orally and can be taken with or without food ( 2.2 ). 2.1 Recommended Assessments for Safety To assess for metabolic acidosis, obtain baseline serum bicarbonate prior to initiating ZONISADE, and obtain periodic serum bicarbonate during treatment [see Warnings and Precautions ( 5.8 )]. 2.2 Recommended Dosage Administer ZONISADE once or twice daily with or without food. The recommended initial dosage of ZONISADE is 100 mg daily. The dosage may be increased by 100 mg daily every two weeks, based on clinical response and tolerability, to 400 mg daily. Patients who are tolerating ZONISADE at 400 mg daily and require further reduction of seizures may be increased up to a maximum dosage of 600 mg daily. However, evidence from controlled trials shows no suggestion of increasing response above 400 mg/day [see Clinical Studies ( 14 )] . 2.3 Important Administration Information Shake well before every administration. To administer ZONISADE directly into the mouth, it is important that ZONISADE be…

Zonisamide side effects

The following clinically signification adverse reactions are described elsewhere in the labeling: • Potentially Fatal Reactions to Sulfonamides [see Warnings and Precautions ( 5.1 )] • Serious Skin Reactions [see Warnings and Precautions ( 5.2 )] • Serious Hematologic Events [see Warnings and Precautions ( 5.3 )] • Drug Reaction with Eosinophilia and Systemic Symptoms (DRESS)/Multi-Organ Hypersensitivity [see Warnings and Precautions ( 5.4 )] • Oligohidrosis and Hyperthermia in Pediatric Patients [see Warnings and Precautions ( 5.5 )] • Acute Myopia and Secondary Angle Closure Glaucoma [see Warnings and Precautions ( 5.6 )] • Suicidal Behavior and Ideation [see Warnings and Precautions ( 5.7 )] • Metabolic Acidosis [see Warnings and Precautions ( 5.8 )] • Seizures on Withdrawal of Antiepileptic Drugs [see Warnings and Precautions ( 5.9 )] • Teratogenicity [see Warnings and Precautions ( 5.10 )] • Cognitive/Neuropsychiatric Adverse Reactions [see Warnings and Precautions ( 5.11 )] • Hyperammonemia and Encephalopathy [see Warnings and Precautions ( 5.12 )] • Kidney Stones [see Warnings and Precautions ( 5.13 )] • Effect on Renal Function [see Warnings and Precautions ( 5.14 )] • Status Epilepticus [see Warnings and Precautions ( 5.15 )] The most common adverse reactions with ZONISADE (an incidence at least 4% greater than placebo) in controlled clinical trials and shown in…

Every zonisamide product we track (2)

Same active ingredient — different manufacturer, form, price and FDA recall record. That last one is what our independent score measures.

Zonisamide products
#	Drug	Rating	Type	Form	Generic?	Typical price
1	Zonisade	72/100	Prescription	Suspension	Generic	$3	View →
2	Zonegran	Not yet rated	Prescription	Capsule	Generic	$3

What zonisamide pills look like

Imprint codes, colour and shape from the FDA’s labelling data. Match the imprint on your pill — or search any imprint.

Zonisamide pill imprints
Imprint	Strength	Colour	Shape	Maker
258;258	25 mg	white, white	capsule	—
259;259	50 mg	white, gray	capsule	—
260;260	100 mg	white, orange	capsule	—
G24;25	25 mg	blue, white	capsule	—
ZNS;100	100 mg	pink, white	capsule	—
G24;25	25 mg

Frequently asked questions

What is zonisamide?: ZONISADE (zonisamide oral suspension) is chemically classified as a sulfonamide. The active ingredient is zonisamide, 1,2-benzisoxazole-3-methanesulfonamide. The empirical formula is C 8 H 8 N 2 O 3 S with a molecular weight of 212.23. Zonisamide is a white powder, pKa = 10.2, and is moderately soluble in water (0.80 mg/mL) and 0.1 N HCl (0.50 mg/mL). The chemical structure is: ZONISADE is an aqueous white to off-white liquid oral suspension. Each mL contains 20 mg of zonisamide. Inactive ingredients include carboxymethylcellulose sodium, citric acid monohydrate, microcrystalline cellulose, purified water, sodium benzoate, strawberry flavor, sucralose, trisodium citrate dihydrate, and xanthan gum. Chemical Structure
What kind of drug is zonisamide?: The FDA classifies zonisamide as an anti-epileptic agent. Anti-epileptic (anticonvulsant) drugs calm the abnormal, excessive electrical activity that triggers seizures. They do this by stabilizing overactive sodium or calcium channels in nerve cells, boosting the brain's natural calming chemical GABA, or dampening excitatory signals, which makes nerves less likely to fire uncontrollably. If you are checking whether it is safe to combine with something else, the class is what matters — two drugs from the same class usually should not be stacked.
Can you take zonisamide with other medicines?: It depends on the medicine. We check it against the FDA labels rather than guessing: our interaction checker searches each drug's own label for the other and quotes what it says, naming the section it came from. Run zonisamide against whatever else you take — and remember that a label not naming a drug is not the same as that combination being safe.
What brand names is zonisamide sold under?: We track 2 zonisamide-containing products in the U.S.: Zonisade and Zonegran. They are the same active ingredient; they differ in form, manufacturer, price and FDA recall record.
What forms does zonisamide come in?: Across the brands we track, zonisamide is currently marketed as suspension and capsule, per the FDA's National Drug Code Directory. Each form is dosed differently — follow the label for the exact product you were prescribed.

Sources: FDA openFDA drug label, National Drug Code Directory, and Enforcement (recall) database. This page reproduces public FDA data and is not medical advice. Dosing is set by your prescriber.