Chlorzoxazone

Sold as Paraflex, Parafon Forte Dsc. Every FDA application for this active ingredient: 2 branded and 36 generic.

As of Nov 15, 2026, FDA lists 38 applications for Chlorzoxazone (sold as Paraflex, Parafon Forte Dsc), first approved Aug 15, 1958, with 0 new uses approved and 0 published complete response letters.

First approved: Aug 15, 1958
Applications: 38
New uses approved: 0
Complete response letters: 0
Medicare spending, 2025: $20.3M

Medicare Spending

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


Chlorzoxazone	Part D	$20.3M	+32%	20,048
Lorzone	Part D	$0K	-100%	0

What Pharmacies Pay

Median price per unit across package codes in CMS's weekly NADAC survey, Nov 11, 2026, before rebates; see every drug's price change

CHLORZOXAZONE 250 MG TABLET: $2.52 per unitGeneric · new this year
CHLORZOXAZONE 375 MG TABLET: $0.667 per unitGeneric · +18% in a year
CHLORZOXAZONE 500 MG TABLET: $0.219 per unitGeneric · -1% in a year
CHLORZOXAZONE 750 MG TABLET: $0.652 per unitGeneric · -4% in a year

Clinical Trials

1 open or ongoing study names this ingredient as an intervention, including as a comparator; newest first. See all

Study	Phase	Status	Posted
Effectiveness of Chlorzoxazone Versus Orphenadrine Citrate in Alleviating Bruxism PainOrofacial Pain, Bruxism · University of Baghdad	Phase 4	Recruiting	Aug 7, 2025

Applications

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


Aug 15, 1958	Parafon Forte DscNDA 11529 · New combination	Janssen R And D	24	Discontinued
Oct 6, 1981	ChlorzoxazoneANDA 86901	Watson Labs	2	Discontinued
Sep 20, 1983	ChlorzoxazoneANDA 87981	Chartwell Rx	5	Discontinued
May 8, 1987	ChlorzoxazoneANDA 88928	Actavis Elizabeth	7	Discontinued
May 4, 1988	ChlorzoxazoneANDA 89852	Rising	5	Discontinued
May 4, 1988	ChlorzoxazoneANDA 89853	Aurobindo Pharma Ltd	5	Marketed
May 4, 1988	ChlorzoxazoneANDA 89895	Barr	15	Discontinued
May 4, 1988	ChlorzoxazoneANDA 89859	Watson Labs	31	Marketed
Dec 23, 1988	Strifon Forte DscANDA 81008	Ferndale Labs	3	Discontinued
Aug 22, 1989	ChlorzoxazoneANDA 81040	Watson Labs	9	Discontinued
Sep 27, 1990	ChlorzoxazoneANDA 89970	Sun Pharm Industries	9	Discontinued
Jul 29, 1991	ChlorzoxazoneANDA 81019	Watson Labs	2	Discontinued
Dec 29, 1993	ChlorzoxazoneANDA 81298	Ohm Labs	1	Discontinued
Dec 29, 1993	ChlorzoxazoneANDA 81299	Ohm Labs	1	Discontinued
Sep 29, 1995	ChlorzoxazoneANDA 40113	Actavis Elizabeth	1	Discontinued
Aug 9, 1996	ChlorzoxazoneANDA 40137	Watson Labs	2	Discontinued
Jun 1, 2010	ChlorzoxazoneANDA 40861	Pharmobedient	1	Marketed
Jun 24, 2016	ChlorzoxazoneANDA 207483	Pharmobedient	0	Marketed
Sep 12, 2019	ChlorzoxazoneANDA 212254	Novitium Pharma	0	Marketed
Nov 27, 2019	ChlorzoxazoneANDA 212253	Novitium Pharma	0	Marketed
May 26, 2020	ChlorzoxazoneANDA 212185	Glenmark Pharms Ltd	0	Discontinued
Jun 17, 2020	ChlorzoxazoneANDA 212898	Teva Pharms USA Inc	0	Discontinued
Jul 21, 2020	ChlorzoxazoneANDA 211849	Dr Reddys Labs SA	0	Marketed
Sep 14, 2020	ChlorzoxazoneANDA 212053	Chartwell Rx	0	Discontinued
Nov 2, 2020	ChlorzoxazoneANDA 212743	Ph Health	0	Marketed
Jul 29, 2021	ChlorzoxazoneANDA 215158	Pharmazone	0	Marketed
Apr 5, 2022	ChlorzoxazoneANDA 213126	Rising	0	Marketed
Oct 20, 2022	ChlorzoxazoneANDA 214941	Macleods Pharms	0	Marketed
Jan 24, 2023	ChlorzoxazoneANDA 215540	Ajenat Pharms	0	Marketed
Jan 27, 2023	ChlorzoxazoneANDA 212047	Somerset Theraps LLC	0	Marketed
Apr 10, 2023	ChlorzoxazoneANDA 214702	Macleods Pharms	0	Marketed
Apr 27, 2023	ChlorzoxazoneANDA 214365	Pharmazone	0	Discontinued
Aug 9, 2023	ChlorzoxazoneANDA 216925	Rising	0	Marketed
Jan 22, 2024	ChlorzoxazoneANDA 210961	Pharmazone	0	Marketed
—	ParaflexNDA 11300	Ortho Mcneil Pharm	0	Discontinued
—	ChlorzoxazoneANDA 86948	Watson Labs	2	Discontinued
—	ChlorzoxazoneANDA 89592	Pioneer Pharms	0	Discontinued
—	ChlorzoxazoneANDA 89948	Pioneer Pharms	0	Discontinued

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