Chlorzoxazone

Product NDC: 55289-633
Requested package NDC: 55289-633-24
11-digit product format: 552890633
Labeler code: 55289
Product ID: 55289-633_419b15d3-6522-5d1c-e063-6394a90abbd0
Type: HUMAN PRESCRIPTION DRUG
Nonproprietary name: Chlorzoxazone
Dosage form: TABLET
Route: ORAL
Labeler: PD-Rx Pharmaceuticals, Inc.
Application: ANDA089859
Marketing category: ANDA
Marketing start: 2011-08-22
Substance: CHLORZOXAZONE
Active strength: 500 mg/1
Pharmacologic classes: Centrally-mediated Muscle Relaxation [PE], Muscle Relaxant [EPC]
NDC exclude flag: No
Listing certified through: 2026-12-31
Current FDA listing: Yes

Source provenance: Browse the complete Orange Book source catalog · source snapshot 43.

Orange Book products#

Current product rows page 1 of 1 · 1 matching rows.

Application-product, Trade name, Ingredient table
Application-product	Trade name	Ingredient	Strength	Dosage form / route	TE codes	RLD / RS	Approval date
A089859-001	CHLORZOXAZONE	CHLORZOXAZONE	500MG	TABLET / ORAL	AA	RS	1988-05-04

Therapeutic equivalence codes#

Current TE-code rows page 1 of 1 · 1 matching rows.

Application-product, TE code table
Application-product	TE code
A089859-001	AA

Observed Orange Book product history#

Observed FDA ZIP history: Each table is queried independently by exact application/product key from successfully parsed Orange Book snapshots. Capture times identify archived source observations; absence or a change between snapshots is not inferred. FDA publication files that were not recoverable as structured ZIP data are not represented as states.

Product history page 1 of 2 · 43 observed states.

Captured, Edition, Application-product table
Captured	Edition	Application-product	Trade name	Strength	Dosage form / route	Product TE source text	RLD / RS	Approval date	Source SHA-256
2026-09-14 22:38:34	2026-08	A089859-001	CHLORZOXAZONE	500MG	TABLET / ORAL	AA	RS	1988-05-04	`84e616aacf4f…`
2026-08-18 06:07:40	2026-07	A089859-001	CHLORZOXAZONE	500MG	TABLET / ORAL	AA	RS	1988-05-04	`caaa826d4ba7…`
2026-02-19 14:30 UTC	2026-02	A089859-001	CHLORZOXAZONE	500MG	TABLET / ORAL	AA	RS	1988-05-04	`011fe1cb6892…`
2025-12-14 10:44 UTC · 2 captures of this ZIP	2025-12	A089859-001	CHLORZOXAZONE	500MG	TABLET / ORAL	AA	RS	1988-05-04	`31067a03dcf5…`
2025-08-23 18:47 UTC	2025-08	A089859-001	CHLORZOXAZONE	500MG	TABLET / ORAL	AA	RS	1988-05-04	`6a471c1ec25d…`
2025-03-22 03:13 UTC · 3 captures of this ZIP	2025-03	A089859-001	CHLORZOXAZONE	500MG	TABLET / ORAL	AA	RS	1988-05-04	`fd3edfee7708…`
2025-02-26 10:13 UTC · 3 captures of this ZIP	2025-02	A089859-001	CHLORZOXAZONE	500MG	TABLET / ORAL	AA	RS	1988-05-04	`b8a1b40f171c…`
2025-01-19 17:59 UTC · 7 captures of this ZIP	2025-01	A089859-001	CHLORZOXAZONE	500MG	TABLET / ORAL	AA	RS	1988-05-04	`03ed91905a0d…`
2024-12-13 21:23 UTC · 2 captures of this ZIP	2024-12	A089859-001	CHLORZOXAZONE	500MG	TABLET / ORAL	AA	RS	1988-05-04	`2680178bc6a6…`
2024-09-14 05:58 UTC · 2 captures of this ZIP	2024-09	A089859-001	CHLORZOXAZONE	500MG	TABLET / ORAL	AA	RS	1988-05-04	`5bbf6a4d5a75…`
2024-11-08 22:44 UTC · 3 captures of this ZIP	2024-11	A089859-001	CHLORZOXAZONE	500MG	TABLET / ORAL	AA	RS	1988-05-04	`d8e5a09893c0…`
2024-10-29 15:01 UTC	2024-10	A089859-001	CHLORZOXAZONE	500MG	TABLET / ORAL	AA	RS	1988-05-04	`d06236e962d9…`
2024-08-13 05:28 UTC · 3 captures of this ZIP	2024-08	A089859-001	CHLORZOXAZONE	500MG	TABLET / ORAL	AA	RS	1988-05-04	`79d66fd596c7…`
2024-07-13 05:37 UTC · 2 captures of this ZIP	2024-07	A089859-001	CHLORZOXAZONE	500MG	TABLET / ORAL	AA	RS	1988-05-04	`301d65b070ca…`
2024-06-18 03:08 UTC · 5 captures of this ZIP	2024-06	A089859-001	CHLORZOXAZONE	500MG	TABLET / ORAL	AA	RS	1988-05-04	`1e350fbaab3a…`
2024-05-31 18:47 UTC	2024-05	A089859-001	CHLORZOXAZONE	500MG	TABLET / ORAL	AA	RS	1988-05-04	`8072bd15b7f6…`
2022-06-29 02:47 UTC · 2 captures of this ZIP	2022-06	A089859-001	CHLORZOXAZONE	500MG	TABLET / ORAL	AA	RS	1988-05-04	`5c6f7cd8ea54…`
2022-04-08 23:34 UTC	2022-04	A089859-001	CHLORZOXAZONE	500MG	TABLET / ORAL	AA	RS	1988-05-04	`5d02ea3f76ae…`
2022-04-04 05:41 UTC	2022-04	A089859-001	CHLORZOXAZONE	500MG	TABLET / ORAL	AA	RS	1988-05-04	`4b0b4de00fa7…`
2019-12-13 00:20 UTC	2019-12	A089859-001	CHLORZOXAZONE	500MG	TABLET / ORAL	AA	RS	1988-05-04	`74a2ff9319b5…`
2022-03-09 01:35 UTC	2022-03	A089859-001	CHLORZOXAZONE	500MG	TABLET / ORAL	AA	RS	1988-05-04	`bb7c543d1eb4…`
2021-12-28 21:50 UTC	2021-12	A089859-001	CHLORZOXAZONE	500MG	TABLET / ORAL	AA	RS	1988-05-04	`782e0a99824c…`
2021-05-05 16:15 UTC · 3 captures of this ZIP	2021-05	A089859-001	CHLORZOXAZONE	500MG	TABLET / ORAL	AA	RS	1988-05-04	`87673890dc5c…`
2021-03-12 10:30 UTC	2021-03	A089859-001	CHLORZOXAZONE	500MG	TABLET / ORAL	AA	RS	1988-05-04	`5aa47cf7b7d7…`
2020-12-22 03:56 UTC	2020-12	A089859-001	CHLORZOXAZONE	500MG	TABLET / ORAL	AA	RS	1988-05-04	`8869cabd3fbd…`
2020-11-12 02:37 UTC	2020-11	A089859-001	CHLORZOXAZONE	500MG	TABLET / ORAL	AA	RS	1988-05-04	`c0c555d07b60…`
2019-12-14 00:12 UTC	2019-12	A089859-001	CHLORZOXAZONE	500MG	TABLET / ORAL	AA	RS	1988-05-04	`3f01610625f2…`
2019-09-15 20:21 UTC	2019-09	A089859-001	CHLORZOXAZONE	500MG	TABLET / ORAL		RS	1988-05-04	`b00525d2431f…`
2019-07-19 19:46 UTC	2019-07	A089859-001	CHLORZOXAZONE	500MG	TABLET / ORAL		RS	1988-05-04	`ea99ee380514…`
2024-03-16 18:09 UTC · 4 captures of this ZIP	2024-03	A089859-001	CHLORZOXAZONE	500MG	TABLET / ORAL	AA	RS	1988-05-04	`6a51e52b5d6a…`
2024-02-18 07:12 UTC	2024-02	A089859-001	CHLORZOXAZONE	500MG	TABLET / ORAL	AA	RS	1988-05-04	`1c564ffb4f44…`
2023-12-20 04:57 UTC	2023-12	A089859-001	CHLORZOXAZONE	500MG	TABLET / ORAL	AA	RS	1988-05-04	`ea1830bbd6c7…`
2023-11-28 05:40 UTC · 2 captures of this ZIP	2023-11	A089859-001	CHLORZOXAZONE	500MG	TABLET / ORAL	AA	RS	1988-05-04	`a72a2bbeb626…`
2023-10-25 00:34 UTC · 2 captures of this ZIP	2023-10	A089859-001	CHLORZOXAZONE	500MG	TABLET / ORAL	AA	RS	1988-05-04	`9b2671bbb829…`
2023-07-15 15:27 UTC · 2 captures of this ZIP	2023-07	A089859-001	CHLORZOXAZONE	500MG	TABLET / ORAL	AA	RS	1988-05-04	`a67488948f0b…`
2023-06-13 01:57 UTC · 3 captures of this ZIP	2023-06	A089859-001	CHLORZOXAZONE	500MG	TABLET / ORAL	AA	RS	1988-05-04	`3f0d92c62455…`
2023-05-13 08:27 UTC	2023-05	A089859-001	CHLORZOXAZONE	500MG	TABLET / ORAL	AA	RS	1988-05-04	`053a50430f4f…`
2023-01-26 05:58 UTC	2023-01	A089859-001	CHLORZOXAZONE	500MG	TABLET / ORAL	AA	RS	1988-05-04	`3bdfa0b2c4d7…`
2022-11-12 20:34 UTC · 5 captures of this ZIP	2022-11	A089859-001	CHLORZOXAZONE	500MG	TABLET / ORAL	AA	RS	1988-05-04	`3a93d1ddd44b…`
2022-10-28 04:53 UTC	2022-10	A089859-001	CHLORZOXAZONE	500MG	TABLET / ORAL	AA	RS	1988-05-04	`f41ea6bd6efb…`

Observed Orange Book normalized TE history#

Normalized TE history page 1 of 2 · 41 observed states.

Captured, Edition, Application-product table
Captured	Edition	Application-product	TE code	Order	Source SHA-256
2026-09-14 22:38:34	2026-08	A089859-001	AA	1	`84e616aacf4f…`
2026-08-18 06:07:40	2026-07	A089859-001	AA	1	`caaa826d4ba7…`
2026-02-19 14:30 UTC	2026-02	A089859-001	AA	1	`011fe1cb6892…`
2025-12-14 10:44 UTC · 2 captures of this ZIP	2025-12	A089859-001	AA	1	`31067a03dcf5…`
2025-08-23 18:47 UTC	2025-08	A089859-001	AA	1	`6a471c1ec25d…`
2025-03-22 03:13 UTC · 3 captures of this ZIP	2025-03	A089859-001	AA	1	`fd3edfee7708…`
2025-02-26 10:13 UTC · 3 captures of this ZIP	2025-02	A089859-001	AA	1	`b8a1b40f171c…`
2025-01-19 17:59 UTC · 7 captures of this ZIP	2025-01	A089859-001	AA	1	`03ed91905a0d…`
2024-12-13 21:23 UTC · 2 captures of this ZIP	2024-12	A089859-001	AA	1	`2680178bc6a6…`
2024-09-14 05:58 UTC · 2 captures of this ZIP	2024-09	A089859-001	AA	1	`5bbf6a4d5a75…`
2024-11-08 22:44 UTC · 3 captures of this ZIP	2024-11	A089859-001	AA	1	`d8e5a09893c0…`
2024-10-29 15:01 UTC	2024-10	A089859-001	AA	1	`d06236e962d9…`
2024-08-13 05:28 UTC · 3 captures of this ZIP	2024-08	A089859-001	AA	1	`79d66fd596c7…`
2024-07-13 05:37 UTC · 2 captures of this ZIP	2024-07	A089859-001	AA	1	`301d65b070ca…`
2024-06-18 03:08 UTC · 5 captures of this ZIP	2024-06	A089859-001	AA	1	`1e350fbaab3a…`
2024-05-31 18:47 UTC	2024-05	A089859-001	AA	1	`8072bd15b7f6…`
2022-06-29 02:47 UTC · 2 captures of this ZIP	2022-06	A089859-001	AA	1	`5c6f7cd8ea54…`
2022-04-08 23:34 UTC	2022-04	A089859-001	AA	1	`5d02ea3f76ae…`
2022-04-04 05:41 UTC	2022-04	A089859-001	AA	1	`4b0b4de00fa7…`
2019-12-13 00:20 UTC	2019-12	A089859-001	AA	1	`74a2ff9319b5…`
2022-03-09 01:35 UTC	2022-03	A089859-001	AA	1	`bb7c543d1eb4…`
2021-12-28 21:50 UTC	2021-12	A089859-001	AA	1	`782e0a99824c…`
2021-05-05 16:15 UTC · 3 captures of this ZIP	2021-05	A089859-001	AA	1	`87673890dc5c…`
2021-03-12 10:30 UTC	2021-03	A089859-001	AA	1	`5aa47cf7b7d7…`
2020-12-22 03:56 UTC	2020-12	A089859-001	AA	1	`8869cabd3fbd…`
2020-11-12 02:37 UTC	2020-11	A089859-001	AA	1	`c0c555d07b60…`
2019-12-14 00:12 UTC	2019-12	A089859-001	AA	1	`3f01610625f2…`
2024-03-16 18:09 UTC · 4 captures of this ZIP	2024-03	A089859-001	AA	1	`6a51e52b5d6a…`
2024-02-18 07:12 UTC	2024-02	A089859-001	AA	1	`1c564ffb4f44…`
2023-12-20 04:57 UTC	2023-12	A089859-001	AA	1	`ea1830bbd6c7…`
2023-11-28 05:40 UTC · 2 captures of this ZIP	2023-11	A089859-001	AA	1	`a72a2bbeb626…`
2023-10-25 00:34 UTC · 2 captures of this ZIP	2023-10	A089859-001	AA	1	`9b2671bbb829…`
2023-07-15 15:27 UTC · 2 captures of this ZIP	2023-07	A089859-001	AA	1	`a67488948f0b…`
2023-06-13 01:57 UTC · 3 captures of this ZIP	2023-06	A089859-001	AA	1	`3f0d92c62455…`
2023-05-13 08:27 UTC	2023-05	A089859-001	AA	1	`053a50430f4f…`
2023-01-26 05:58 UTC	2023-01	A089859-001	AA	1	`3bdfa0b2c4d7…`
2022-11-12 20:34 UTC · 5 captures of this ZIP	2022-11	A089859-001	AA	1	`3a93d1ddd44b…`
2022-10-28 04:53 UTC	2022-10	A089859-001	AA	1	`f41ea6bd6efb…`
2022-09-29 23:25 UTC	2022-09	A089859-001	AA	1	`e64feba35796…`
2022-07-09 03:26 UTC · 3 captures of this ZIP	2022-07	A089859-001	AA	1	`cb3db0bc1861…`

Reported adverse events (FAERS/openFDA)#

Adverse event summaries are temporarily unavailable. Other product information remains available.

Additional Listing Data#

Finished product: Yes
Brand name base: Chlorzoxazone
Listing expiration: 2026-12-31

Active Ingredients#

Ingredient, Strength table
Ingredient	Strength
CHLORZOXAZONE	500 mg/1

Harmonized UNII identifiers#

UNII identifiers page 1 of 1 · 1 matching rows.

Identifier, FDA.report destination table
Identifier	FDA.report destination
H0DE420U8G	Internal UNII lookup

Harmonized RxCUI identifiers#

RxCUI identifiers page 1 of 1 · 1 matching rows.

Identifier, FDA.report destination table
Identifier	FDA.report destination
197502	Internal RxNorm lookup

Harmonized SPL set identifiers#

SPL set identifiers page 1 of 1 · 1 matching rows.

Identifier, FDA.report destination table
Identifier	FDA.report destination
8650d342-92df-48d7-9f3d-cdd6f6f4c0e7	Available on FDA.report

DailyMed Product Concepts#

Product concept, Relation, Version table
Product concept	Relation	Version	Effective
a7ba9d15-162f-2741-f0fc-3516be5e88bd	Product name	7	20250114
cbf4a4f8-16cb-4546-a0cc-fd91bbe774f2	Product name	2	20240223
0a48cfb8-244e-463e-aa85-fd9bbbc9190a	Product name	2	20200224

DailyMed Package Descriptions#

Package NDC, Product, Description table
Package NDC	Product	Description	Form	Quantity	SPL version
55289-633-10	Chlorzoxazone	10 in 1 BOTTLE, PLASTIC	TABLET	10	30
55289-633-20	Chlorzoxazone	20 in 1 BOTTLE, PLASTIC	TABLET	20	30
55289-633-24	Chlorzoxazone	24 in 1 BOTTLE, PLASTIC	TABLET	24	30
55289-633-28	Chlorzoxazone	28 in 1 BOTTLE, PLASTIC	TABLET	28	30
55289-633-30	Chlorzoxazone	30 in 1 BOTTLE, PLASTIC	TABLET	30	30
55289-633-40	Chlorzoxazone	40 in 1 BOTTLE, PLASTIC	TABLET	40	30

DailyMed Billing Units#

Package NDC, Billing unit, Product NDC table
Package NDC	Billing unit	Product NDC	DailyMed indexing SPL	SPL version	Effective
55289-633-10	EA - Each	55289-633	389dff79-c9c7-4c94-9229-e8e320e8d569	1	2012-07-24
55289-633-20	EA - Each	55289-633	eedbd3ae-247e-407a-a00f-f23da2adeb19	1	2012-07-24
55289-633-24	EA - Each	55289-633	dc828efa-4306-4d6e-acf8-54fbb7263646	1	2012-07-24
55289-633-28	EA - Each	55289-633	a82c1ce5-cf19-43d9-b24f-1ca0ab0baf3e	1	2012-07-24
55289-633-30	EA - Each	55289-633	ed2e7612-0cae-4fed-a9d6-8f373d942940	1	2012-07-24
55289-633-40	EA - Each	55289-633	8548f2ce-97fe-4a83-9649-97f1df49fec6	1	2012-07-24

DailyMed Socrata Ingredients#

Ingredient, Type, UNII table
Ingredient	Type	UNII	DailyMed label	SPL version
CHLORZOXAZONE	ACTIVE INGREDIENT	H0DE420U8G	CHLORZOXAZONE TABLET [PD-RX PHARMACEUTICALS, INC.]	15
CHLORZOXAZONE	ACTIVE MOIETY	H0DE420U8G	CHLORZOXAZONE TABLET [PD-RX PHARMACEUTICALS, INC.]	15
CELLULOSE, MICROCRYSTALLINE	INACTIVE INGREDIENT	OP1R32D61U	CHLORZOXAZONE TABLET [PD-RX PHARMACEUTICALS, INC.]	15
DOCUSATE SODIUM	INACTIVE INGREDIENT	F05Q2T2JA0	CHLORZOXAZONE TABLET [PD-RX PHARMACEUTICALS, INC.]	15
LACTOSE MONOHYDRATE	INACTIVE INGREDIENT	EWQ57Q8I5X	CHLORZOXAZONE TABLET [PD-RX PHARMACEUTICALS, INC.]	15
MAGNESIUM STEARATE	INACTIVE INGREDIENT	70097M6I30	CHLORZOXAZONE TABLET [PD-RX PHARMACEUTICALS, INC.]	15
SODIUM BENZOATE	INACTIVE INGREDIENT	OJ245FE5EU	CHLORZOXAZONE TABLET [PD-RX PHARMACEUTICALS, INC.]	15
SODIUM STARCH GLYCOLATE TYPE A POTATO	INACTIVE INGREDIENT	5856J3G2A2	CHLORZOXAZONE TABLET [PD-RX PHARMACEUTICALS, INC.]	15
STARCH, PREGELATINIZED CORN	INACTIVE INGREDIENT	O8232NY3SJ	CHLORZOXAZONE TABLET [PD-RX PHARMACEUTICALS, INC.]	15

DailyMed Dashboard NDC Coverage#

NDC, Dashboard title, SPL version table
NDC	Dashboard title	SPL version	Validation	Dashboard ZIP
55289-633	CHLORZOXAZONE TABLET [PD-RX PHARMACEUTICALS, INC.]	29	Current NDC, Legacy NDC, 6 package rows	20241006_8650d342-92df-48d7-9f3d-cdd6f6f4c0e7.zip

openFDA label cross-check#

OpenFDA label data provides additional search and identifier links. DailyMed’s Structured Product Label is the canonical label on FDA.report. Matching records are deduplicated before they are shown below.

Matched openFDA labels page 1 of 1 · 5 matching rows.

Brand, Generic, Manufacturer table
Brand	Generic	Manufacturer	SPL set ID	Effective date	Available safety fields	Join
Chlorzoxazone	CHLORZOXAZONE	PD-Rx Pharmaceuticals, Inc.	8650d342-92df-48d7-9f3d-cdd6f6f4c0e7	2025-10-20	Warnings, Adverse reactions	Exact identifier application applno (ANDA): 089859 application number: ANDA089859 ndc (package): 55289-633-24 ndc (product): 55289-633 ndc11 (package): 55289063324
Chlorzoxazone	CHLORZOXAZONE	Bryant Ranch Prepack	5e6889c9-a091-4622-0a00-ad0fc1830f78	2024-10-08	Warnings, Adverse reactions	Exact identifier application applno (ANDA): 089859 application number: ANDA089859
Chlorzoxazone	CHLORZOXAZONE	Actavis Pharma, Inc.	2f05e8e2-616f-475b-ac9f-c42e1a5dbe81	2024-08-25	Warnings, Adverse reactions	Exact identifier application applno (ANDA): 089859 application number: ANDA089859
Chlorzoxazone	CHLORZOXAZONE	A-S Medication Solutions	6c418b8f-4a1c-4611-80d5-3a3a7dbca9c8	2023-03-08	Warnings, Adverse reactions	Exact identifier application applno (ANDA): 089859 application number: ANDA089859
Chlorzoxazone	CHLORZOXAZONE	Proficient Rx LP	63338935-f3dd-4ef1-bb66-856a83c95f41	2022-04-01	Warnings, Adverse reactions	Exact identifier application applno (ANDA): 089859 application number: ANDA089859

UNII, Preferred term, Registry number table
UNII	Preferred term	Registry number	Matched term
H0DE420U8G	CHLORZOXAZONE	95-25-0	CHLORZOXAZONE

DailyMed RxNorm Mappings#

RxCUI, RxNorm string, TTY table
RxCUI	RxNorm string	TTY	DailyMed	SPL version
197502	chlorzoxazone 500 MG Oral Tablet	PSN	8650d342-92df-48d7-9f3d-cdd6f6f4c0e7	30
197502	chlorzoxazone 500 MG Oral Tablet	SCD	8650d342-92df-48d7-9f3d-cdd6f6f4c0e7	30

Packages#

Package NDC, 11-digit format, Description table
Package NDC	11-digit format	Description	Units	Marketing start	Marketing end	Sample	Exclude flag	Status
55289-633-24	55289063324	24 TABLET in 1 BOTTLE, PLASTIC (55289-633-24)	24 tablet	2011-08-31	0000-00-00	No	No	Current

Title, Manufacturer, Effective date table
Title	Manufacturer	Effective date	Type	Version
Chlorzoxazone Tablets, USP Rx only	PD-Rx Pharmaceuticals, Inc.	2025-10-20	HUMAN PRESCRIPTION DRUG LABEL	30