Zonisamide
ZONEGRAN
What it isSodium- and calcium-channel-blocking antiepileptic with carbonic anhydrase inhibition; focal seizures.
Why this oneOnce-daily use and frequent weight loss distinguish it from many antiseizure drugs.
What limits itKidney stones and metabolic acidosis require attention; cognitive slowing, reduced sweating, and sulfonamide reactions can occur.
FDA-approved for
- seizures (2000)
Off-label
- migraine prophylaxis
- binge-eating disorder
FDA label
Read the full label on DailyMed ↗
| FDA dosing | Population | Start | Target | Max |
|---|---|---|---|---|
| Partial seizures (adjunctive) | Adults ≥16 yr | 100 mg QD | 100-400 mg/day (QD or BID) | 600 mg/day |
Titration Increase no sooner than every 2 weeks (long half-life; up to 2 weeks to reach steady state)
Renal Use caution; may require slower titration and more frequent monitoring in renal disease
Hepatic Use caution; may require slower titration and more frequent monitoring in hepatic disease
Long half-life — allow ≥2 weeks at each dose level to reach steady state
Instructions
- Swallow capsules whole; take once or twice daily with or without food
Contraindications
- Hypersensitivity to sulfonamides
Cautions
- DRESS and serious skin reactions
- Metabolic acidosis (monitor, including in pregnancy)
- Acute myopia and secondary angle-closure glaucoma
- Hyperammonemia and encephalopathy
- Acute pancreatitis and rhabdomyolysis (postmarketing)
- CNS effects: somnolence, cognitive/memory difficulty, ataxia
- Suicidal behavior/ideation (antiepileptic class effect)
Adverse reactions
- Somnolence
- Anorexia
- Dizziness
- Ataxia
- Agitation/irritability
- Difficulty with memory/concentration
- Nausea
- Headache
Pregnancy May cause fetal harm — teratogenic in animals (cardiovascular malformations, embryolethality); can cause metabolic acidosis; monitor mother and neonate.
Lactation Undefined
NO BOXED WARNINGS
Principal riskKidney stones; sulfonamide cross-reactivity
Cost, est. cash$5–$150/month
Generic entry2005
Classes and tags
Clinical profile
Legacy pregnancy categoryC
Defining liabilityMetabolic acidosis, kidney stones, serious rash and reduced sweating/heat injury.
Mechanism of action: Zonisamide ballicule
Open Zonisamide in the interactive console ↗
Memory aids: mascots and interaction avatars
seismic hazard ZONes → anti-seizure med
angry face → may cause irritability
