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ZARONTIN

NDA

ETHOSUXIMIDE | N012380 | PARKE DAVIS DIV WARNER LAMBERT CO

1 strength0 unique patents0 unique exclusivities

PTAB Proceedings

No IPR/PGR/CBM challenges found at the Patent Trial and Appeal Board

Patent Reexaminations

No ex parte or inter partes reexamination proceedings found at USPTO

Hatch-Waxman Litigation

No ANDA patent litigation cases (NOS 835) matched from PACER

Citizen Petitions

No FDA citizen petitions matched from Regulations.gov

Clinical Trials

9 trials from ClinicalTrials.gov — 2 recruiting, 4 completed

Trial	Phase	Status	Sponsor	Enrollment	Dates
Ethosuximide and Pentoxifylline in the Treatment of Abdominal Pain Related to Irritable Bowel Syndrome NCT04217733	Phase 3	Recruiting	Tanta University	60	2019-11-01 → 2030-12-30
Ketogenic Diet for New-Onset Absence Epilepsy NCT04274179	Phase 3	Recruiting	Johns Hopkins University	40	2020-08-10 → 2028-05-01
Childhood Absence Epilepsy Rx PK-PD-Pharmacogenetics Study NCT00088452	Phase 3	Completed	Children's Hospital Medical Center, Cincinnati	453	2004-07 → 2016-08-31
Investigate the Clinical Responses of Ethosuximide in Patients With Treatment-Resistant Depression.NCT03887624	Early Phase 1	Completed	Zhejiang University	16	2019-05-21 → 2021-04-01
Ethosuximide to Treat IBS NCT02973542	Phase 2	Completed	University Hospital, Clermont-Ferrand	162	2018-02-08 → 2023-05-07
Chemotherapy Induced Painful Peripheral Neuropathy Ethosuximide (The CIN-E Study)NCT01278004	Phase 2	Completed	Royal Marsden NHS Foundation Trust	15	2010-05 → 2014-07
Safety and Efficacy Study of Ethosuximide for the Treatment of Complex Regional Pain Syndrome (CRPS)NCT00689585	Phase 2	Terminated	McGill University Health Centre/Research Institute of the McGill University Health Centre	4	2008-09 → 2010-07
Comparison of a Drug and Placebo in the Prevention of Migraine Headaches NCT01122381	Phase 1/2	Terminated	US Department of Veterans Affairs	5	2011-12 → 2014-04
Ketogenic Diet in Infants With Epilepsy (KIWE)NCT02205931	Phase 4	UNKNOWN	University College, London	160	2015-01 → 2019-06

Source: ClinicalTrials.gov. Trials matched by ingredient name.

Drug Pricing (NADAC)

National Average Drug Acquisition Cost — Week of 2026-07-15 | 1 NDC

Highest NADAC/Unit

$1.31

per ea

Lowest NADAC/Unit

$1.31

per ea

Brand NDCs

Generic NDCs

NDC Description	NADAC/Unit	Unit	Type	Generic NADAC	Effective
00071023724ZARONTIN 250 MG CAPSULE	$1.31	EA	Brand	$0.2523	2026-01-01

Source: NADAC (data.medicaid.gov). Prices reflect national average acquisition costs for retail community pharmacies.

VA Federal Supply Schedule

Government-negotiated contract prices | 2 NDCs (1 FSS, 1 Big4)

Lowest Price

$70.30

Highest Price

$134.29

FSS NDCs

Big4 NDCs

Description	Price	Type	Vendor	Contract End
00071-0237-24ZARONTIN	$134.29	FSS	Pfizer Inc.	06/30/2029
00071-0237-24ZARONTIN	$70.30	Big4	Pfizer Inc.	06/30/2029

Source: VA Federal Supply Schedule (va.gov). Prices are government-negotiated contract prices.

Medicare Part D Spending

CMS annual spending data for Zarontin (2024)

Total Spending

$67K

Total Claims

298

Beneficiaries

Avg Cost/Unit

$1.13

Spending Trend

$466K(2019)→$425K(2020)→$428K(2021)→$394K(2022)→$217K(2023)→$67K(2024)

YoY Change:-66.3%

5yr CAGR:-23.0%

Source: CMS Medicare Part D Spending by Drug (2024). Shows gross drug cost under Part D.

API Supply Chain1 active DMF

1 active API supplier hold Drug Master Files for this ingredient. Limited supplier base — potential supply chain risk.

KATWIJK CHEMIE BVETHOSUXIMIDE

DMF 79371989

Source: FDA Drug Master Files (fda.gov). Type II API DMFs matched by ingredient.

Approval Letters

11 letters from Drugs@FDA

Date	Submission	Document
Oct 29, 2021	SUPPL -37	View Letter (PDF)
May 20, 2016	SUPPL -36	View Letter (PDF)
May 9, 2012	SUPPL -34	View Letter (PDF)
Jun 17, 2011	SUPPL -33	View Letter (PDF)
Sep 20, 2010	SUPPL -32	View Letter (PDF)
Apr 29, 2009	SUPPL -31	View Letter (PDF)
Sep 18, 2006	SUPPL -30	View Letter (PDF)
Apr 19, 2002	SUPPL -29	View Letter (PDF)
Apr 9, 2001	SUPPL -25	View Letter (PDF)
Apr 9, 2001	SUPPL -22	View Letter (PDF)
Apr 9, 2001	SUPPL -23	View Letter (PDF)

Source: Drugs@FDA application documents.

Products (1)

#001 — 250MG

RLDAB

0 patents0 exclusivities▴

CAPSULE;ORAL | Approved: Approved Prior to Jan 1, 1982

No patent or exclusivity listings for this strength.