Chlorzoxazone

Summary

Chlorzoxazone (INN) is a centrally acting muscle relaxant used to treat muscle spasm and the resulting pain or discomfort. It can also be administered for acute pain in general and for tension headache (muscle contraction headache). It acts on the spinal cord by depressing reflexes. It is sold under the brand names Lorzone, Paraflex and Muscol and in combination form as Parafon Forte, a combination of chlorzoxazone and acetaminophen (paracetamol). Possible side effects include dizziness, lightheadedness, malaise, nausea, vomiting, and liver dysfunction. When used with acetaminophen it has added risk of hepatotoxicity.[medical citation needed]

Chlorzoxazone
Clinical data
Trade namesLorzone, Paraflex, Muscol
AHFS/Drugs.comMonograph
MedlinePlusa682577
License data
Routes of
administration
By mouth
Drug classSkeletal muscle relaxants
ATC code
Legal status
Legal status
Pharmacokinetic data
BioavailabilityWell absorbed
Protein binding13–18%
MetabolismHepatic
Elimination half-life1.1 hours
Duration of action3–4 hours
Excretionurine (<1%)
Identifiers
  • 5-chloro-3H-benzooxazol-2-one
CAS Number
  • 95-25-0 checkY
PubChem CID
  • 2733
IUPHAR/BPS
  • 2322
DrugBank
  • DB00356 checkY
ChemSpider
  • 2632 checkY
UNII
  • H0DE420U8G
KEGG
  • D00771 checkY
ChEBI
  • CHEBI:3655 checkY
ChEMBL
  • ChEMBL1371 checkY
CompTox Dashboard (EPA)
  • DTXSID9022813 Edit this at Wikidata
ECHA InfoCard100.002.186 Edit this at Wikidata
Chemical and physical data
FormulaC7H4ClNO2
Molar mass169.56 g·mol−1
3D model (JSmol)
  • Interactive image
  • Clc2cc1c(OC(=O)N1)cc2
  • InChI=1S/C7H4ClNO2/c8-4-1-2-6-5(3-4)9-7(10)11-6/h1-3H,(H,9,10) checkY
  • Key:TZFWDZFKRBELIQ-UHFFFAOYSA-N checkY
  (verify)

It is available as a generic medication.[3]

Like metaxalone, its mechanism of action is still in question. It is believed that metaxalone works by altering serotonin levels and acting as a mild MAO inhibitor.[medical citation needed] The mechanism of action of chlorzoxazone is thought[by whom?] to act on GABAA and GABAB receptors and voltage-gated calcium channels to a degree.[medical citation needed] General central nervous system depression is the only currently accepted aspect to its medical benefits.[medical citation needed] Elucidation of the exact mechanism of action is ongoing but there is limited study due to the existence of more effective, safe muscle relaxants (e.g., diazepam, cyclobenzaprine, tizanidine), greatly limiting the potential benefit of identifying novel compounds which share chlorzoxazone's mechanism of action.

See also edit

References edit

  1. ^ "Parafon DSC- chlorzoxazone tablet". DailyMed. 9 February 2010. Retrieved 5 November 2020.
  2. ^ "Lorzone- chlorzoxazone tablet". DailyMed. 21 June 2019. Retrieved 5 November 2020.
  3. ^ "Competitive Generic Therapy Approvals". U.S. Food and Drug Administration (FDA). 29 June 2023. Archived from the original on 29 June 2023. Retrieved 29 June 2023.

Further reading edit

  • 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. S2CID 20092326.
  • 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.

External links edit

  • "Chlorzoxazone". Drug Information Portal. U.S. National Library of Medicine.
  • Chloroxazone Safety Data Sheet Archived 2019-07-12 at the Wayback Machine
  • D.F. Marsh, U.S. patent 2,895,877 (1959)