Chlorzoxazone

Chlorzoxazone

Systematic (IUPAC) name
5-chloro-3H-benzooxazol-2-one
Clinical data
Trade names	Parafonforte
AHFS/Drugs.com	monograph
MedlinePlus	a682577
Pregnancy cat.	?
Legal status	?
Routes	oral
Pharmacokinetic data
Bioavailability	well absorbed
Protein binding	13–18%
Metabolism	hepatic
Half-life	1.1 hr
Excretion	urine (<1%)
Identifiers
CAS number	95-25-0 Y
ATC code	M03BB03
PubChem	CID 2733
DrugBank	APRD00308
ChemSpider	2632 Y
UNII	H0DE420U8G Y
KEGG	D00771 Y
ChEBI	CHEBI:3655 Y
ChEMBL	CHEMBL1371 Y
Chemical data
Formula	C7H4ClNO2
Mol. mass	169.565 g/mol
SMILES	eMolecules & PubChem
InChI InChI=1S/C7H4ClNO2/c8-4-1-2-6-5(3-4)9-7(10)11-6/h1-3H,(H,9,10) Y Key:TZFWDZFKRBELIQ-UHFFFAOYSA-N Y
N (what is this?)  (verify)

Chlorzoxazone is a centrally acting muscle relaxant used to treat muscle spasm and the resulting pain or discomfort. It acts on the spinal cord by depressing reflexes. It is sold as Muscol or Parafon Forte, a combination of chlorzoxazone and acetaminophen (Paracetamol). Possible side effects include dizziness, lightheadedness, malaise, nausea, vomiting, and liver dysfunction. Used with acetaminophen it has added risk of hepatoxicity, which is why the combination is not recommended. For a more in depth look at Chlorzoxazone visit http://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?id=15262.

Chemistry

Chlorzoxazone, 5-chloro-2-benzoxazolione, is synthesized by a hetercyclization reaction of 2-amino-4-chlorphenol with phosgene.

• D.F. Marsh, U.S. Patent 2,895,877 (1959).

External links

• Dong DL, Luan Y, Feng TM, Fan CL, Yue P, Sun ZJ, Gu RM, Yang BF. (2006). "Chlorzoxazone inhibit contraction of rat thoracic aorta". Eur J Pharmacol 545 (2–3): 161–6. doi:10.1016/j.ejphar.2006.06.063. PMID 16859676. 
• Park J, Kim K, Park P, Ha J (2006). "Effect of high-dose aspirin on CYP2E1 activity in healthy subjects measured using chlorzoxazone as a probe". J Clin Pharmacol 46 (1): 109–14. doi:10.1177/0091270005282635. PMID 16397290. 
• Wan J, Ernstgård L, Song B, Shoaf S (2006). "Chlorzoxazone metabolism is increased in fasted Sprague-Dawley rats". J Pharm Pharmacol 58 (1): 51–61. doi:10.1211/jpp.58.1.0007. PMC 1388188. PMID 16393464. http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1388188.