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Live data · NADAC + Part D CY24 · reviewed daily

Primidone (Mysoline)

Primidone prevents seizures by stabilizing electrical activity in the brain.

First FDA approval1978-12-01
Generic availableYes · 7 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

$70.7M in CY2024 Part D spend2.2M claims · 564K beneficiaries · 329 plans surveyed

Lowest NADAC
$0.096/unit
20 NDCs benchmarked, lowest of all strengths.
Average NADAC
$0.116
Across all dosage forms in distribution.
Highest NADAC
$0.231
Range is tight.
Plans with PA
0 / 329
Zero PA friction — switching is purely formulary.

Questions a plan sponsor actually asks.

FAQPage schema11 entries indexed · 4 visible
What is Primidone used for?

Primidone prevents seizures by stabilizing electrical activity in the brain.

Is there a generic for Primidone?

Yes. 14 ANDAs filed at FDA, 7 generic manufacturers currently shipping.

How much does my plan pay for Primidone?

Across 329 Part D plans, Primidone averages $0.116/unit (NADAC). Lowest available: $0.096/unit. Highest in distribution: $0.231/unit.

Is Primidone on the FDA shortage list?

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

7 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
Ethosuximide
Brand: Zarontin
$0.092Lowest NADAC
8Generic mfrs
$2.3MCY24 Part D spend
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02
Felbamate
Brand: Felbatol
$0.368Lowest NADAC
5Generic mfrs
$20.0MCY24 Part D spend
Compare →
03
Lamotirigine
Brand: Lamotrigine
Lowest NADAC
0Generic mfrs
CY24 Part D spend
Compare →
04
Lamotrigine
Brand: LAMICTAL
$0.029Lowest NADAC
22Generic mfrs
$327.2MCY24 Part D spend
Compare →
05
Lamotrigine Chewable Dispersible
Brand: lamotrigine
Lowest NADAC
0Generic mfrs
CY24 Part D spend
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06
Lamotrigine Er
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 (10 approvals on file) · NADAC unit costs: CMS NADAC weekly file (20 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.