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Live data · NADAC + Part D CY24 · reviewed daily

Ethosuximide (Zarontin)

Ethosuximide prevents seizures by stabilizing electrical activity in the brain.

First FDA approval2000-09-22
Generic availableYes · 8 mfrs
Shortage statusNone
340B exposureunknown
Last updated
NADAC: weekly (every Wed)Part D Formulary: quarterlyPart D Spend: annual (CY24)Orange Book: weeklyShortages: daily
At a glance · the numbers a plan sponsor wants on screen one

$2.3M in CY2024 Part D spend24K claims · 4K beneficiaries · 329 plans surveyed

Lowest NADAC
$0.092/unit
9 NDCs benchmarked, lowest of all strengths.
Average NADAC
$0.331
Across all dosage forms in distribution.
Highest NADAC
$1.31
Wide spread — brand-strength NDCs still in market.
Plans with PA
0 / 329
Zero PA friction — switching is purely formulary.

Questions a plan sponsor actually asks.

FAQPage schema12 entries indexed · 4 visible
What is Ethosuximide used for?

Ethosuximide prevents seizures by stabilizing electrical activity in the brain.

Is there a generic for Ethosuximide?

Yes. 8 ANDAs filed at FDA, 8 generic manufacturers currently shipping.

How much does my plan pay for Ethosuximide?

Across 329 Part D plans, Ethosuximide averages $0.331/unit (NADAC). Lowest available: $0.092/unit. Highest in distribution: $1.31/unit.

Is Ethosuximide on the FDA shortage list?

No. Ethosuximide is not currently on the FDA Drug Shortage Database.

8 additional drug-specific questions are indexed in the page's FAQPage schema for search engines and LLM crawlers, beyond what renders visually above. View page source for the complete JSON-LD.

Same class. Different math.

Anti-epileptic Agent6 alternatives in D1
01
Felbamate
Brand: Felbatol
$0.368Lowest NADAC
5Generic mfrs
$20.0MCY24 Part D spend
Compare →
02
Lamotirigine
Brand: Lamotrigine
Lowest NADAC
0Generic mfrs
CY24 Part D spend
Compare →
03
Lamotrigine
Brand: LAMICTAL
$0.029Lowest NADAC
22Generic mfrs
$327.2MCY24 Part D spend
Compare →
04
Lamotrigine Chewable Dispersible
Brand: lamotrigine
Lowest NADAC
0Generic mfrs
CY24 Part D spend
Compare →
05
Lamotrigine Er
Anti-epileptic Agent
$0.371Lowest NADAC
0Generic mfrs
CY24 Part D spend
Compare →
06
Lamotrigine Extended Release
Anti-epileptic Agent
$0.371Lowest NADAC
0Generic mfrs
CY24 Part D spend
Compare →

Sources · every number above traces back.

Last refresh30 May 2026

Drug identity, dosage forms, brand names: openFDA NDC Directory · First approval, ANDA history: FDA Orange Book (9 approvals on file) · NADAC unit costs: CMS NADAC weekly file (9 NDCs benchmarked) · Formulary tier and PA placement: CMS Part D Formulary file (329 plans) · Annualized spend, claims, beneficiaries: CMS Part D Spending Dashboard (CY2024) · Shortage status: FDA Drug Shortage Database · 340B exposure: HRSA OPAIS. Methodology and reproducibility notes on /methodology.