Two medicines, side by side
Topiramate vs zonisamide
Topiramate and zonisamide are both labeled for seizures and epilepsy. Drugs@FDA records approvals of topiramate since 1996 and of zonisamide since 2000. Pharmacies paid $0.0567 per topiramate 100 mg tablet and $0.106 per zonisamide 100 mg capsule (NADAC, October 7, 2026). Zonisamide's other strengths are brand-only: $2.75 per mL (Zonisade 100 mg/5 mL oral suspension).
Check it at the source: the topiramate FDA label on DailyMed (effective June 1, 2026); the zonisamide FDA label on DailyMed (effective June 4, 2026).
Highlights of the topiramate record
Topiramate (Topamax) · label of June 1, 2026
Used for
From the label: indicationsTopiramate is indicated for: Epilepsy: initial monotherapy for the treatment of partial-onset or primary generalized tonic-clonic seizures in patients 2 years of age and older (1.1); adjunctive therapy for the treatment of partial-onset seizures, primary generalized tonic-clonic seizures, or seizures associated with Lennox- Gastaut syndrome in patients 2 years of age and older (1.2) Preventive treatment of migraine […]
On the market
- Earliest approval on file
- December 24, 1996
- Generic labelers
- 47 labelers
- Pharmacy cost
- $0.0567 per tablet
Supply and safety
- Shortage
- No current entry
- Recalls
- 10
Highlights of the zonisamide record
Zonisamide (Zonegran) · label of June 4, 2026
Used for
From the label: indicationsZonisamide is indicated as adjunctive therapy in the treatment of partial seizures in adults with epilepsy.
On the market
- Earliest approval on file
- March 27, 2000
- Generic labelers
- 20 labelers
- Pharmacy cost
- $0.106 per capsule
Supply and safety
- Shortage
- No current entry
- Recalls
- 11
Source: FDA drug labels via openFDA (Topiramate label of June 1, 2026, Zonisamide label of June 4, 2026); NDC Directory, Drugs@FDA, NADAC, FDA shortages and recalls (October 8, 2026)
How do topiramate and zonisamide differ on the record?
Half-life, in each label's words: Topiramate, “The mean plasma elimination half-life is 21 hours after single or multiple doses.”; Zonisamide, “The elimination half-life of zonisamide in plasma is approximately 63 hours.”
Generics: topiramate since 2003; zonisamide since 2005 (Drugs@FDA).
| Topiramate | Zonisamide | |
|---|---|---|
| Labeled for | Seizures and epilepsy, Migraine | Seizures and epilepsy |
| Pharmacologic class | n/a | Anti-epileptic Agent |
| How it works (label) | The precise mechanisms by which topiramate exerts its anticonvulsant and preventive migraine effects are unknown; however, preclinical studies have revealed four properties that may contribute to topiramate's efficacy for epilepsy and the … | n/a |
| Half-life (label) | The mean plasma elimination half-life is 21 hours after single or multiple doses. | The elimination half-life of zonisamide in plasma is approximately 63 hours. |
| Earliest approval on file (Drugs@FDA) | December 24, 1996 | March 27, 2000 |
| First generic approved | December 17, 2003 | December 22, 2005 |
| Generic labelers (NDC) | 47 labelers | 20 labelers |
| Pharmacy cost (NADAC, each one's most listed form; strengths differ) | $0.0567 per tablet (Topiramate 100 mg tablet) | $0.106 per capsule (Zonisamide 100 mg capsule) |
| 12-month price change | -10% | -1% |
| Boxed warning | No | No |
| Shortage now | No current entry | No current entry |
| Recalls recorded | 10 | 11 |
| FAERS reports (a report is not proof of cause; counts follow how widely a medicine is used) | 91,067 | 10,560 |
| DEA schedule | none | none |
Source: Drugs@FDA, FDA NDC Directory, CMS NADAC of October 7, 2026, FDA shortages and recalls, FAERS via openFDA (FDA files October 8, 2026)
Do their labels mention each other?
Zonisamide label, warningsThe risks of hyperammonemia and various manifestations of encephalopathy may be increased in patients treated with zonisamide and concomitantly taking other medications that can cause hyperammonemia, including valproic acid or topiramate (see PRECAUTIONS ).
Zonisamide label, warnings and precautionsThe risks of hyperammonemia and various manifestations of encephalopathy may be increased in patients treated with zonisamide and concomitantly taking other medications that can cause hyperammonemia, including valproic acid or topiramate [see Warnings and Precautions ( 5 )].
Source: FDA drug labels via openFDA
What do the labels say about using others of their kind?
Topiramate label, drug interactionsBecause of the potential of topiramate to cause CNS depression, as well as other cognitive and/or neuropsychiatric adverse reactions, topiramate should be used with extreme caution if used in combination with alcohol and other CNS depressants.
Source: FDA drug labels via openFDA
What next?
- Alternatives to topiramate
- every medicine labeled for the same conditions