Ethosuximide

Controls absence (petit mal) epilepsy. Sold as Zarontin. Every FDA application for this active ingredient: 1 branded and 9 generic.

As of Nov 13, 2026, FDA lists 10 applications for Ethosuximide (sold as Zarontin), first approved Nov 2, 1960, with 0 new uses approved and 0 published complete response letters.

First approved: Nov 2, 1960
Applications: 10
New uses approved: 0
Complete response letters: 0
Medicare spending, 2025: $1.6M

Medicare Spending

CMS Part D and Part B, 2025, before manufacturer rebates; matched by generic name


Ethosuximide	Part D	$1.5M	+4%	2,268
Zarontin	Part D	$64K	-5%	51

Clinical Trials

2 open or ongoing studies name this ingredient as an intervention, including as a comparator; newest first. See all


Ketogenic Diet for New-Onset Absence EpilepsyAbsence Epilepsy, Ketogenic Dieting · Johns Hopkins University	Phase 3	Recruiting	Feb 18, 2020
Ethosuximide and Pentoxifylline in the Treatment of Abdominal Pain Related to Irritable Bowel SyndromeIBS - Irritable Bowel Syndrome · Tanta University	Phase 3	Recruiting	Jan 3, 2020

Applications

NDAs, BLAs and generic ANDAs for this ingredient, oldest first; each opens its full history


Nov 2, 1960	ZarontinNDA 12380 · New molecular entity	Parke Davis	24	Marketed
Feb 13, 1974	ZarontinANDA 80258	Parke-Davis	14	Marketed
Jul 30, 1993	EthosuximideANDA 81306	Teva Pharms	13	Discontinued
Nov 22, 2000	EthosuximideANDA 40253	Pharm Assoc	5	Marketed
Oct 28, 2002	EthosuximideANDA 40430	Bionpharma	7	Marketed
Dec 22, 2003	EthosuximideANDA 40506	Chartwell Rx	5	Marketed
May 28, 2008	EthosuximideANDA 40686	Epic Pharma LLC	5	Marketed
Sep 25, 2012	EthosuximideANDA 200892	Heritage Pharms Inc	2	Discontinued
Feb 19, 2019	EthosuximideANDA 211928	Onesource	2	Marketed
Mar 16, 2020	EthosuximideANDA 210654	Puracap Pharm LLC	1	Marketed

Applications, approvals and products come from FDA's Drugs@FDA data files, refreshed weekly, grouped by active ingredient as FDA spells it. Complete response letters are FDA's published letters. Medicare spending is CMS's Part D and Part B dashboard, matched to this ingredient by generic name; shortages are FDA's shortage list, matched by application number; clinical trials are ClinicalTrials.gov studies naming the ingredient as an intervention, refreshed daily; safety programs are FDA's REMS list, matched by application number or, for shared programs, by ingredient. Drugs@FDA