U.S. Department of Health & Human Services Divider Arrow National Institutes of Health Divider Arrow NCATS

Details

Stereochemistry ACHIRAL
Molecular Formula C7H4ClNO2
Molecular Weight 169.565
Optical Activity NONE
Defined Stereocenters 0 / 0
E/Z Centers 0
Charge 0

SHOW SMILES / InChI
Structure of CHLORZOXAZONE

SMILES

ClC1=CC=C2OC(=O)NC2=C1

InChI

InChIKey=TZFWDZFKRBELIQ-UHFFFAOYSA-N
InChI=1S/C7H4ClNO2/c8-4-1-2-6-5(3-4)9-7(10)11-6/h1-3H,(H,9,10)

HIDE SMILES / InChI

Molecular Formula C7H4ClNO2
Molecular Weight 169.565
Charge 0
Count
Stereochemistry ACHIRAL
Additional Stereochemistry No
Defined Stereocenters 0 / 0
E/Z Centers 0
Optical Activity NONE

Description
Curator's Comment: description was created based on several sources, including https://www.ncbi.nlm.nih.gov/mesh/68002753

Chlorzoxazone is a centrally acting central muscle relaxant with sedative properties. It is claimed to inhibit muscle spasm by exerting an effect primarily at the level of the spinal cord and subcortical areas of the brain where it inhibits multisynaptic reflex arcs involved in producing and maintaining skeletal muscle spasm of varied etiology. The clinical result is a reduction of the skeletal muscle spasm with relief of pain and increased mobility of the involved muscles. Chlorzoxazone is indicated as an adjunct to rest, physical therapy, and other measures for the relief of discomfort associated with acute, painful musculoskeletal conditions. The mode of action of this drug has not been clearly identified, but may be related to its sedative properties. Chlorzoxazone does not directly relax tense skeletal muscles in man.

Originator

Curator's Comment: Marsh, D.F.; US. Patent 2,895,877; July 21, 1959; assigned to McNeil Laboratories, Inc.

Approval Year

Targets

Targets

Conditions

Conditions

ConditionModalityTargetsHighest PhaseProduct
Primary
CHLORZOXAZONE

Approved Use

INDICATIONS & USAGE SECTION Chlorzoxazone is indicated as an adjunct to rest, physical therapy, and other measures for the relief of discomfort associated with acute, painful musculoskeletal conditions. The mode of action of this drug has not been clearly identified, but may be related to its sedative properties. Chlorzoxazone does not directly relax tense skeletal muscles in man.

Launch Date

5.7870719E11
Cmax

Cmax

ValueDoseCo-administeredAnalytePopulation
36.3 μg/mL
750 mg single, oral
dose: 750 mg
route of administration: Oral
experiment type: SINGLE
co-administered: ACETAMINOPHEN
CHLORZOXAZONE plasma
Homo sapiens
population: HEALTHY
age: ADULT
sex: MALE
food status: FASTED
5.1 μg/mL
250 mg single, oral
dose: 250 mg
route of administration: Oral
experiment type: SINGLE
co-administered: QUERCETIN
CHLORZOXAZONE plasma
Homo sapiens
population: HEALTHY
age: ADULT
sex: MALE
food status: FASTED
3.45 μg/mL
250 mg single, oral
dose: 250 mg
route of administration: Oral
experiment type: SINGLE
co-administered:
CHLORZOXAZONE plasma
Homo sapiens
population: HEALTHY
age: ADULT
sex: MALE
food status: FASTED
15 μg/mL
500 mg single, oral
dose: 500 mg
route of administration: Oral
experiment type: SINGLE
co-administered:
CHLORZOXAZONE serum
Homo sapiens
population: HEALTHY
age: ADULT
sex: FEMALE / MALE
food status: FED
5.2 μg/mL
500 mg single, oral
dose: 500 mg
route of administration: Oral
experiment type: SINGLE
co-administered:
CHLORZOXAZONE serum
Homo sapiens
population: UNHEALTHY
age: ADULT
sex: FEMALE / MALE
food status: FED
12.2 μg/mL
500 mg single, oral
dose: 500 mg
route of administration: Oral
experiment type: SINGLE
co-administered:
CHLORZOXAZONE serum
Homo sapiens
population: UNHEALTHY
age: ADULT
sex: FEMALE / MALE
food status: FED
0.14 μg/mL
250 mg single, oral
dose: 250 mg
route of administration: Oral
experiment type: SINGLE
co-administered: QUERCETIN
6-HYDROXYCHLORZOXAZONE plasma
Homo sapiens
population: HEALTHY
age: ADULT
sex: MALE
food status: FASTED
0.2 μg/mL
250 mg single, oral
dose: 250 mg
route of administration: Oral
experiment type: SINGLE
co-administered:
6-HYDROXYCHLORZOXAZONE plasma
Homo sapiens
population: HEALTHY
age: ADULT
sex: MALE
food status: FASTED
AUC

AUC

ValueDoseCo-administeredAnalytePopulation
4084 μg × h/mL
750 mg single, oral
dose: 750 mg
route of administration: Oral
experiment type: SINGLE
co-administered: ACETAMINOPHEN
CHLORZOXAZONE plasma
Homo sapiens
population: HEALTHY
age: ADULT
sex: MALE
food status: FASTED
16.69 μg × h/mL
250 mg single, oral
dose: 250 mg
route of administration: Oral
experiment type: SINGLE
co-administered: QUERCETIN
CHLORZOXAZONE plasma
Homo sapiens
population: HEALTHY
age: ADULT
sex: MALE
food status: FASTED
9.86 μg × h/mL
250 mg single, oral
dose: 250 mg
route of administration: Oral
experiment type: SINGLE
co-administered:
CHLORZOXAZONE plasma
Homo sapiens
population: HEALTHY
age: ADULT
sex: MALE
food status: FASTED
43.5 mg × h/L
500 mg single, oral
dose: 500 mg
route of administration: Oral
experiment type: SINGLE
co-administered:
CHLORZOXAZONE serum
Homo sapiens
population: HEALTHY
age: ADULT
sex: FEMALE / MALE
food status: FED
15.7 μg × h/mL
500 mg single, oral
dose: 500 mg
route of administration: Oral
experiment type: SINGLE
co-administered:
CHLORZOXAZONE serum
Homo sapiens
population: UNHEALTHY
age: ADULT
sex: FEMALE / MALE
food status: FED
32.8 μg × h/mL
500 mg single, oral
dose: 500 mg
route of administration: Oral
experiment type: SINGLE
co-administered:
CHLORZOXAZONE serum
Homo sapiens
population: UNHEALTHY
age: ADULT
sex: FEMALE / MALE
food status: FED
0.64 μg × h/mL
250 mg single, oral
dose: 250 mg
route of administration: Oral
experiment type: SINGLE
co-administered: QUERCETIN
6-HYDROXYCHLORZOXAZONE plasma
Homo sapiens
population: HEALTHY
age: ADULT
sex: MALE
food status: FASTED
0.95 μg × h/mL
250 mg single, oral
dose: 250 mg
route of administration: Oral
experiment type: SINGLE
co-administered:
6-HYDROXYCHLORZOXAZONE plasma
Homo sapiens
population: HEALTHY
age: ADULT
sex: MALE
food status: FASTED
T1/2

T1/2

ValueDoseCo-administeredAnalytePopulation
1.12 h
750 mg single, oral
dose: 750 mg
route of administration: Oral
experiment type: SINGLE
co-administered: ACETAMINOPHEN
CHLORZOXAZONE plasma
Homo sapiens
population: HEALTHY
age: ADULT
sex: MALE
food status: FASTED
1.65 h
250 mg single, oral
dose: 250 mg
route of administration: Oral
experiment type: SINGLE
co-administered: QUERCETIN
CHLORZOXAZONE plasma
Homo sapiens
population: HEALTHY
age: ADULT
sex: MALE
food status: FASTED
1.21 h
250 mg single, oral
dose: 250 mg
route of administration: Oral
experiment type: SINGLE
co-administered:
CHLORZOXAZONE plasma
Homo sapiens
population: HEALTHY
age: ADULT
sex: MALE
food status: FASTED
1.1 h
500 mg single, oral
dose: 500 mg
route of administration: Oral
experiment type: SINGLE
co-administered:
CHLORZOXAZONE serum
Homo sapiens
population: HEALTHY
age: ADULT
sex: FEMALE / MALE
food status: FED
1.4 h
500 mg single, oral
dose: 500 mg
route of administration: Oral
experiment type: SINGLE
co-administered:
CHLORZOXAZONE serum
Homo sapiens
population: UNHEALTHY
age: ADULT
sex: FEMALE / MALE
food status: FED
1.2 h
500 mg single, oral
dose: 500 mg
route of administration: Oral
experiment type: SINGLE
co-administered:
CHLORZOXAZONE serum
Homo sapiens
population: UNHEALTHY
age: ADULT
sex: FEMALE / MALE
food status: FED
Funbound

Funbound

ValueDoseCo-administeredAnalytePopulation
3.9%
500 mg single, oral
dose: 500 mg
route of administration: Oral
experiment type: SINGLE
co-administered:
CHLORZOXAZONE serum
Homo sapiens
population: HEALTHY
age: ADULT
sex: FEMALE / MALE
food status: FED
3.2%
500 mg single, oral
dose: 500 mg
route of administration: Oral
experiment type: SINGLE
co-administered:
CHLORZOXAZONE serum
Homo sapiens
population: UNHEALTHY
age: ADULT
sex: FEMALE / MALE
food status: FED
4%
500 mg single, oral
dose: 500 mg
route of administration: Oral
experiment type: SINGLE
co-administered:
CHLORZOXAZONE serum
Homo sapiens
population: UNHEALTHY
age: ADULT
sex: FEMALE / MALE
food status: FED
Overview

Overview

CYP3A4CYP2C9CYP2D6hERG

OverviewOther

Other InhibitorOther SubstrateOther Inducer



Drug as victim
PubMed

PubMed

TitleDatePubMed
[Rhabdomyolysis and cholestatic hepatitis under treatment with simvastatin and chlorzoxazone].
1999 Apr 3
Metabolism of benzene in human liver microsomes: individual variations in relation to CYP2E1 expression.
1999 Feb
CYP2E1-dependent benzene toxicity: the role of extrahepatic benzene metabolism.
1999 Jun-Jul
Pharmacological activation of cloned intermediate- and small-conductance Ca(2+)-activated K(+) channels.
2000 Mar
High-throughput cytochrome P450 (CYP) inhibition screening via a cassette probe-dosing strategy. VI. Simultaneous evaluation of inhibition potential of drugs on human hepatic isozymes CYP2A6, 3A4, 2C9, 2D6 and 2E1.
2001
Effects of organic solvents on the activities of cytochrome P450 isoforms, UDP-dependent glucuronyl transferase, and phenol sulfotransferase in human hepatocytes.
2001 Feb
Assessment of CFTR chloride channel openers in intact normal and cystic fibrosis murine epithelia.
2001 Feb
Characterization of xenobiotic-metabolizing cytochrome P450 (CYP) forms in ringed and grey seals from the Baltic Sea and reference sites.
2001 Jan
One hundred percent online identity check of pharmaceutical products by near-infrared spectroscopy on the packaging line.
2001 Jan
Synthetic chloride channel restores glutathione secretion in cystic fibrosis airway epithelia.
2001 Jul
Genetic repeat polymorphism in the regulating region of CYP2E1: frequency and relationship with enzymatic activity in alcoholics.
2001 Jun
Identification of multiple constitutive and inducible hepatic cytochrome P450 enzymes in market weight swine.
2001 Jun
Inhibition of human CYP1A2 activity in vitro by methylxanthines: potent competitive inhibition by 8-phenyltheophylline.
2001 Mar
Cytochrome P450 expression and related metabolism in human buccal mucosa.
2001 Mar
Cytochrome p450-dependent metabolism of trichloroethylene in rat kidney.
2001 Mar
Modulation of recombinant small-conductance Ca(2+)-activated K(+) channels by the muscle relaxant chlorzoxazone and structurally related compounds.
2001 Mar
Tissue-specific alterations in the 6-hydroxylation of chlorzoxazone following traumatic brain injury in the rat.
2001 Mar
In vitro inhibition of cytochrome P450 enzymes in human liver microsomes by a potent CYP2A6 inhibitor, trans-2-phenylcyclopropylamine (tranylcypromine), and its nonamine analog, cyclopropylbenzene.
2001 Mar
Mitochondrial dysfunction by gamma-irradiation accompanies the induction of cytochrome P450 2E1 (CYP2E1) in rat liver.
2001 Mar 21
A comparison of aroclor 1254-induced and uninduced rat liver microsomes to human liver microsomes in phenytoin O-deethylation, coumarin 7-hydroxylation, tolbutamide 4-hydroxylation, S-mephenytoin 4'-hydroxylation, chloroxazone 6-hydroxylation and testosterone 6beta-hydroxylation.
2001 May 16
In vitro evaluation of valproic acid as an inhibitor of human cytochrome P450 isoforms: preferential inhibition of cytochrome P450 2C9 (CYP2C9).
2001 Nov
Contribution of CYP1A2 in the hepatic metabolism of melatonin: studies with isolated microsomal preparations and liver slices.
2001 Nov
Low doses of nicotine and ethanol induce CYP2E1 and chlorzoxazone metabolism in rat liver.
2001 Nov
Mechanism of aerobic transformation of carbon tetrachloride by poplar cells.
2002
Effect of methacrylonitrile on cytochrome P-450 2E1 (CYP2E1) expression in male F344 rats.
2002 Apr 12
Validated HPLC method for determination of chlorzoxazone in human serum and its application in a clinical pharmacokinetic study.
2002 Dec
The alkaloid rutaecarpine is a selective inhibitor of cytochrome P450 1A in mouse and human liver microsomes.
2002 Mar
Plasma levels of TNF-alpha and IL-6 are inversely related to cytochrome P450-dependent drug metabolism in patients with congestive heart failure.
2002 Oct
Metabolizing enzyme localization and activities in the first trimester human placenta: the effect of maternal and gestational age, smoking and alcohol consumption.
2002 Oct
Inhibition of cytochrome P450 2E1 by propofol in human and porcine liver microsomes.
2002 Oct 1
Cytochrome P450 2E1 and 3A activities do not differ between Mexicans and European Americans.
2002 Sep
Characterization of vectorial chloride transport pathways in the human pancreatic duct adenocarcinoma cell line HPAF.
2003 Aug
Simultaneous determination of aspirin and isosorbide 5-mononitrate in formulation by reversed phase high pressure liquid chromatography.
2003 Aug 21
Essential requirements for substrate binding affinity and selectivity toward human CYP2 family enzymes.
2003 Jan 1
Determination of 6-hydroxychlorzoxazone and chlorzoxazone in porcine microsome samples.
2003 Jan 25
Stimulatory effects of chlorzoxazone, a centrally acting muscle relaxant, on large conductance calcium-activated potassium channels in pituitary GH3 cells.
2003 Jan 3
Functional characterization of three human cytochrome p450 2E1 variants with amino acid substitutions.
2003 Jun
Cytochrome P450 expression and testosterone metabolism in the liver of deer.
2003 May 1
ATP release triggered by activation of the Ca2+-activated K+ channel in human airway Calu-3 cells.
2004 Mar
Patents

Sample Use Guides

One tablet three or four times daily. If adequate response is not obtained with this dose, it may be increased to one and one-half tablets (750 mg) three or four times daily. As improvement occurs dosage can usually be reduced.
Route of Administration: Oral
Chlorzoxazone did not affect the tension of the rat thoracic artery rings at rest, but relaxed the precontraction induced by 1 uM noradrenaline in an endothelium independent manner. Preincubation with chlorzoxazone also antagonized the contraction induced by 1 uM noradrenaline or 25 mM KCl.
Substance Class Chemical
Created
by admin
on Thu Jul 06 11:00:39 UTC 2023
Edited
by admin
on Thu Jul 06 11:00:39 UTC 2023
Record UNII
H0DE420U8G
Record Status Validated (UNII)
Record Version
  • Download
Name Type Language
CHLORZOXAZONE
INN   JAN   MART.   MI   ORANGE BOOK   USP   USP-RS   VANDF   WHO-DD  
INN  
Official Name English
CHLORZOXAZONE [MART.]
Common Name English
chlorzoxazone [INN]
Common Name English
Chlorzoxazone [WHO-DD]
Common Name English
CHLORZOXAZONE [USP-RS]
Common Name English
5-Chloro-2-benzoxazolinone
Systematic Name English
STRIFON
Brand Name English
CHLORZOXAZONE [JAN]
Common Name English
CHLORZOXAZONE [USP IMPURITY]
Common Name English
PARAFLEX
Brand Name English
CHLORZOXAZONE [MI]
Common Name English
CHLORZOXAZONE [ORANGE BOOK]
Common Name English
PARAFON
Brand Name English
CHLORZOXAZONE [VANDF]
Common Name English
CHLORZOXAZONE [USP MONOGRAPH]
Common Name English
2(3H)-BENZOXAZOLONE, 5-CHLORO-
Systematic Name English
Classification Tree Code System Code
LIVERTOX NBK548137
Created by admin on Thu Jul 06 11:00:39 UTC 2023 , Edited by admin on Thu Jul 06 11:00:39 UTC 2023
NDF-RT N0000175737
Created by admin on Thu Jul 06 11:00:39 UTC 2023 , Edited by admin on Thu Jul 06 11:00:39 UTC 2023
WHO-VATC QM03BB53
Created by admin on Thu Jul 06 11:00:39 UTC 2023 , Edited by admin on Thu Jul 06 11:00:39 UTC 2023
WHO-ATC M03BB03
Created by admin on Thu Jul 06 11:00:39 UTC 2023 , Edited by admin on Thu Jul 06 11:00:39 UTC 2023
WHO-VATC QM03BB03
Created by admin on Thu Jul 06 11:00:39 UTC 2023 , Edited by admin on Thu Jul 06 11:00:39 UTC 2023
WHO-ATC M03BB53
Created by admin on Thu Jul 06 11:00:39 UTC 2023 , Edited by admin on Thu Jul 06 11:00:39 UTC 2023
NDF-RT N0000175730
Created by admin on Thu Jul 06 11:00:39 UTC 2023 , Edited by admin on Thu Jul 06 11:00:39 UTC 2023
WHO-ATC M03BB73
Created by admin on Thu Jul 06 11:00:39 UTC 2023 , Edited by admin on Thu Jul 06 11:00:39 UTC 2023
NCI_THESAURUS C29696
Created by admin on Thu Jul 06 11:00:39 UTC 2023 , Edited by admin on Thu Jul 06 11:00:39 UTC 2023
WHO-VATC QM03BB73
Created by admin on Thu Jul 06 11:00:39 UTC 2023 , Edited by admin on Thu Jul 06 11:00:39 UTC 2023
Code System Code Type Description
ECHA (EC/EINECS)
202-403-9
Created by admin on Thu Jul 06 11:00:39 UTC 2023 , Edited by admin on Thu Jul 06 11:00:39 UTC 2023
PRIMARY
EPA CompTox
DTXSID9022813
Created by admin on Thu Jul 06 11:00:39 UTC 2023 , Edited by admin on Thu Jul 06 11:00:39 UTC 2023
PRIMARY
MESH
D002753
Created by admin on Thu Jul 06 11:00:39 UTC 2023 , Edited by admin on Thu Jul 06 11:00:39 UTC 2023
PRIMARY
FDA UNII
H0DE420U8G
Created by admin on Thu Jul 06 11:00:39 UTC 2023 , Edited by admin on Thu Jul 06 11:00:39 UTC 2023
PRIMARY
DAILYMED
H0DE420U8G
Created by admin on Thu Jul 06 11:00:39 UTC 2023 , Edited by admin on Thu Jul 06 11:00:39 UTC 2023
PRIMARY
IUPHAR
2322
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PRIMARY
CAS
95-25-0
Created by admin on Thu Jul 06 11:00:39 UTC 2023 , Edited by admin on Thu Jul 06 11:00:39 UTC 2023
PRIMARY
EVMPD
SUB06215MIG
Created by admin on Thu Jul 06 11:00:39 UTC 2023 , Edited by admin on Thu Jul 06 11:00:39 UTC 2023
PRIMARY
WIKIPEDIA
CHLORZOXAZONE
Created by admin on Thu Jul 06 11:00:39 UTC 2023 , Edited by admin on Thu Jul 06 11:00:39 UTC 2023
PRIMARY
RXCUI
2410
Created by admin on Thu Jul 06 11:00:39 UTC 2023 , Edited by admin on Thu Jul 06 11:00:39 UTC 2023
PRIMARY RxNorm
ChEMBL
CHEMBL1371
Created by admin on Thu Jul 06 11:00:39 UTC 2023 , Edited by admin on Thu Jul 06 11:00:39 UTC 2023
PRIMARY
CHEBI
3655
Created by admin on Thu Jul 06 11:00:39 UTC 2023 , Edited by admin on Thu Jul 06 11:00:39 UTC 2023
PRIMARY
INN
748
Created by admin on Thu Jul 06 11:00:39 UTC 2023 , Edited by admin on Thu Jul 06 11:00:39 UTC 2023
PRIMARY
MERCK INDEX
M3471
Created by admin on Thu Jul 06 11:00:39 UTC 2023 , Edited by admin on Thu Jul 06 11:00:39 UTC 2023
PRIMARY Merck Index
RS_ITEM_NUM
1130505
Created by admin on Thu Jul 06 11:00:39 UTC 2023 , Edited by admin on Thu Jul 06 11:00:39 UTC 2023
PRIMARY
SMS_ID
100000081896
Created by admin on Thu Jul 06 11:00:39 UTC 2023 , Edited by admin on Thu Jul 06 11:00:39 UTC 2023
PRIMARY
NCI_THESAURUS
C28926
Created by admin on Thu Jul 06 11:00:39 UTC 2023 , Edited by admin on Thu Jul 06 11:00:39 UTC 2023
PRIMARY
DRUG CENTRAL
626
Created by admin on Thu Jul 06 11:00:39 UTC 2023 , Edited by admin on Thu Jul 06 11:00:39 UTC 2023
PRIMARY
PUBCHEM
2733
Created by admin on Thu Jul 06 11:00:39 UTC 2023 , Edited by admin on Thu Jul 06 11:00:39 UTC 2023
PRIMARY
DRUG BANK
DB00356
Created by admin on Thu Jul 06 11:00:39 UTC 2023 , Edited by admin on Thu Jul 06 11:00:39 UTC 2023
PRIMARY
Related Record Type Details
BINDER->LIGAND
BINDING
METABOLIC ENZYME -> SUBSTRATE
EXCRETED UNCHANGED
Related Record Type Details
METABOLITE INACTIVE -> PARENT
MAJOR
URINE
METABOLITE -> PARENT
further metabolized to glucoronide
MAJOR
PLASMA
Related Record Type Details
ACTIVE MOIETY
Name Property Type Amount Referenced Substance Defining Parameters References
Volume of Distribution PHARMACOKINETIC
Biological Half-life PHARMACOKINETIC
Cmax PHARMACOKINETIC ROUTE OF ADMINISTRATION
PHARMACOKINETIC
DOSE
PHARMACOKINETIC
Tmax PHARMACOKINETIC ROUTE OF ADMINISTRATION
PHARMACOKINETIC
DOSE
PHARMACOKINETIC