同: Robaxin

WordNet

muscle relaxant for skeletal muscles (trade name Robaxin) used to treat spasms (同)Robaxin

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出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2015/09/13 18:02:49」(JST)

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Methocarbamol is a central muscle relaxant used to treat skeletal muscle spasms. Under the trade name Robaxin, it is marketed by Actient Pharmaceuticals in the United States and Pfizer in Canada. The mechanism of action of methocarbamol is currently unknown, but may involve the inhibition of carbonic anhydrase.^[2] The muscle relaxant effects of methocarbamol are largely attributed to central depressant effects;^[3] however, peripheral effects of methocarbamol to prolong muscle refractory period have also been reported.^[4]

Metabolism

Methocarbamol is the carbamate of guaifenesin, but does not produce guaifenesin as a metabolite, because the carbamate bond is not hydrolyzed metabolically; metabolism is by Phase I ring hydroxylation and O-demethylation, followed by Phase II conjugation. All the major metabolites are unhydrolyzed carbamates.^[5]^[6]

Marketing

Generic Methocarbamol 750mg Oral Tablet.

Methocarbamol is marketed under different names when presented in combination with other active ingredients. In combination with acetaminophen (Paracetamol), under trade names Robaxacet and Tylenol Body Pain Night, whereas Robax Platinum is the trade name for a formulation of methocarbamol and ibuprofen.^[7]^[8] A combination of methocarbamol and aspirin is marketed as Robaxisal, however in Spain the tradename Robaxisal is used for the Paracetamol combination instead of Robaxacet.

Abuse potential

Unlike other carbamates such as meprobamate and its prodrug carisoprodol, methocarbamol has greatly reduced abuse potential. Studies comparing it to lorazepam (Ativan) and diphenhydramine (Benadryl), along with placebo, find that methocarbamol produces increased "liking" responses and some sedative-like effects, however, at higher doses dysphoria is reported. It is considered to have an abuse profile similar to, but weaker than, lorazepam.^[9]

Side-effects

Potential side-effects include: drowsiness, dizziness, clumsiness (ataxia), upset stomach, flushing, blurred vision, and fever. Both tachycardia (fast heart rate) and bradycardia (slow heart rate) have been reported;^[10]^[11] these can be serious. Other serious side-effects include the development of a severe skin rash or itching, fainting, jaundice, persistent nausea/vomiting, stomach/abdominal pain, mental/mood changes, trouble urinating, signs of infection. If taken in large amounts at once or more than directed or as prescribed, dysphoria or suicidal thoughts may occur.^[12] In addition, methocarbamol may cause urine to turn black, blue, or green. However, this effect is harmless.^[13]

Methocarbamol has a high therapeutic index, i.e. a wide range of safe and effective dosages. Consumer (OTC) doses are in the range 3–6 g per day,^[14] while clinical doses can be as high as 24 g per day for severe conditions such as tetanus.^[15]

Because of potential for side-effects, this drug is considered to be a high-risk medication for the elderly.^[16]

Chemistry

Methocarbamol can be synthesized from guaifenesin by successive reaction with phosgene and then ammonia.^[17]^[18]

Methocarbamol synthesis

References

^ Sica DA, Comstock TJ, Davis J, Manning L, Powell R, Melikian A, Wright G. (1990). "Pharmacokinetics and protein binding of methocarbamol in renal insufficiency and normals". European Journal of Clinical Pharmacology 39 (2): 193–4. doi:10.1007/BF00280060. PMID 2253675.
^ Parr JS, Khalifah RG. (1992). "Inhibition of carbonic anhydrases I and II by N-unsubstituted carbamate esters". J Biol Chem 267 (35): 25044–25050. PMID 1460006.
^ Truitt EB Jr., Little JM. (1958). "A pharmacologic comparison of methocarbamol (AHR-85), the monocarbamate of 3-(o-methoxyphenoxy)-1,2-propanediol with chemically related interneuronal depressant drugs". J Pharmacol Exp Ther 122 (2): 239–246. PMID 13514612.
^ Crankshaw DP, Raper C. (1968). "Some studies on peripheral actions of mephenesin, methocarbamol and diazepam". Br J Pharmacol 34 (3): 579–590. doi:10.1111/j.1476-5381.1968.tb08486.x. PMID 5726787.
^ Methocarbamol. In: DRUGDEX System [intranet database]. Greenwood Village, Colorado: Thomson Healthcare; c1974–2009 [cited 2009 Feb 10].
^ Bruce RB, Turnbull LB, Newman JH. (Jan 1971). "Metabolism of methocarbamol in the rat, dog, and human". J Pharm Sci 60 (1): 104–106. doi:10.1002/jps.2600600120. PMID 5548215.
^ "New Drugs and Indications Reviewed at the May 2003 DEC Meeting" (PDF). ESI Canada. Retrieved 2008-11-14.
^ "Tylenol Body Pain Night Overview and Dosage" (website). Tylenol Canada. Retrieved 2012-04-23.
^ "Subjective and behavioral effects of diphenhydramine, lorazepam and methocarbamol: evaluation of abuse liability". Journal of Pharmacology and Experimental Therapeutics. Retrieved 2011-05-06.
^ medical-dictionary_thefreedictionary-methocarbamol
^ Drugs.com-methocarbamol-side-effects
^ METHOCARBAMOL – ORAL (Robaxin) side effects, medical uses, and drug interactions. Medicinenet.com. Retrieved on 2011-11-09.
^ Methocarbamol: MedlinePlus Drug Information. Nlm.nih.gov. Retrieved on 2011-11-09.
^ http://www.rxlist.com/robaxin-drug/indications-dosage.htm
^ http://www.drugs.com/dosage/methocarbamol.html
^ See NCQA’s HEDIS Measure: Use of High Risk Medications in the Elderly
^ R.S. Murphey, U.S. Patent 2,770,649 (1956)
^ Yale, H. L.; Pribyl, E. J.; Braker, W.; Bergeim, F. H.; Lott, W. A. (1950). "Muscle-relaxing Compounds Similar to 3-(o-Toloxy)-1,2-propanediol.1I. Aromatic Ethers of Polyhydroxy Alcohols and Related Compounds2,3". Journal of the American Chemical Society 72 (8): 3710. doi:10.1021/ja01164a107.

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English Journal

A Review of 29 Incidents Involving 4-Aminopyridine in Non-target Species Reported to the ASPCA Animal Poison Control Center.

McLean MK, Khan S.SourceASPCA Animal Poison Control Center, 1717 S Philo Rd, Suite 36, Urbana, IL, 61802, USA.
Journal of medical toxicology : official journal of the American College of Medical Toxicology.J Med Toxicol.2013 Oct 16. [Epub ahead of print]
4-Aminopyridine (4-AP) is an avicide used in products that are approved by the Environmental Protection Agency (EPA) to control populations of various birds. Pharmaceutical 4-AP is also used in humans to treat neural and muscular dysfunctions associated with multiple sclerosis. Although strict restr
PMID 24129835

Methocarbamol CRI for symptomatic treatment of pyrethroid intoxication: a report of three cases.

Draper WE, Bolfer L, Cottam E, McMichael M, Schubert T.SourceDepartment of Small Animal Clinical Sciences, College of Veterinary Medicine, University of Florida, Gainesville, FL, USA. william.draper.dvm@gmail.com
Journal of the American Animal Hospital Association.J Am Anim Hosp Assoc.2013 Sep-Oct;49(5):325-8. doi: 10.5326/JAAHA-MS-5835. Epub 2013 Mar 27.
Pyrethroids are popular for use in companion animals due to their relatively low mammalian toxicity and efficacy against arthropods. Nonetheless, pyrethroid intoxication has been reported in cats and dogs, and cats appear to be more susceptible due to difficulty in biotransformation and excretion of
PMID 23535756

Selective serotonin reuptake inhibitor (SSRI) toxicosis in cats: 33 cases (2004-2010).

Pugh CM, Sweeney JT, Bloch CP, Lee JA, Johnson JA, Hovda LR.SourceDepartment of Emergency and Critical Care, Ocean State Veterinary Specialists, 1480 South County Trail, East Greenwich, RI 02818.
Journal of veterinary emergency and critical care (San Antonio, Tex. : 2001).J Vet Emerg Crit Care (San Antonio).2013 Sep;23(5):565-70. doi: 10.1111/vec.12091. Epub 2013 Sep 9.
OBJECTIVE: To evaluate a population of cats with selective-serotonin reuptake inhibitor (SSRI) toxicosis and characterize the population affected, list products ingested, the clinical signs observed, treatments performed, length of hospitalization, patient outcome, and overall prognosis.DESIGN: Retr
PMID 24016243

Japanese Journal

Determination of methocarbamol concentration in human plasma by high performance liquid chromatography-tandem mass spectrometry

ZHA Wuyi,ZHU Zhimeng
Journal of chromatography. B, Analytical technologies in the biomedical and life sciences 878(9), 831-835, 2010-03-15
NAID 10028033920

ラットにおける急性ピレスロイド中毒のメトカルバモールによる治療効果

廣森壽彦,中西とし子,川口幸子,佐古博,鈴木隆,宮本純之
日本農薬学会誌 11(1), 9-14, 1986-02-20
雄ラットに致死量のfenvalerate(850mg/kg), cypermethrin(850mg/kg), fenpropathrin(100mg/kg)およびpermethrin(850mg/kg)をそれぞれ経口投与し, 中毒症状の発現にあわせてメトカルバモール[3-(o-methoxy-phenoxy)-1, 2-propanediol 1-carbamate]を腹腔内投与(初回400mg …
NAID 110001712023

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リンク元	「メトカルバモール」

「メトカルバモール」

Methocarbamol
Systematic (IUPAC) name
	(RS)-2-hydroxy-3-(2-methoxyphenoxy)propyl carbamate
Clinical data
AHFS/Drugs.com	monograph
MedlinePlus	a682579
Pregnancy; category	AU: B2; US: C (Risk not ruled out);
Legal status	CA: OTC; US: ℞-only;
Routes of; administration	Oral, intravenous
Pharmacokinetic data
Metabolism	Hepatic
Biological half-life	1.14–1.24 hours
Identifiers
CAS Registry Number	532-03-6
ATC code	M03BA03
PubChem	CID: 4107
IUPHAR/BPS	6829
DrugBank	DB00423
ChemSpider	3964
UNII	125OD7737X
KEGG	D00402
ChEBI	CHEBI:6832
ChEMBL	CHEMBL1201117
Chemical data
Formula	C11H15NO5
Molecular mass	241.241 g/mol
	SMILES O=C(OCC(O)COc1ccccc1OC)N ;
	InChI InChI=1S/C11H15NO5/c1-15-9-4-2-3-5-10(9)16-6-8(13)7-17-11(12)14/h2-5,8,13H,6-7H2,1H3,(H2,12,14) ; Key:GNXFOGHNGIVQEH-UHFFFAOYSA-N ;
(what is this?) (verify)

　　[★]

英: methocarbamol
ラ: methocarbamolum
商: ロバキシン

[halflife-1] Sica DA, Comstock TJ, Davis J, Manning L, Powell R, Melikian A, Wright G. (1990). "Pharmacokinetics and protein binding of methocarbamol in renal insufficiency and normals". European Journal of Clinical Pharmacology 39 (2): 193–4. doi:10.1007/BF00280060. PMID 2253675.

[Parr_Khalifah_1992-2] Parr JS, Khalifah RG. (1992). "Inhibition of carbonic anhydrases I and II by N-unsubstituted carbamate esters". J Biol Chem 267 (35): 25044–25050. PMID 1460006.

[Truitt_Little_1958-3] Truitt EB Jr., Little JM. (1958). "A pharmacologic comparison of methocarbamol (AHR-85), the monocarbamate of 3-(o-methoxyphenoxy)-1,2-propanediol with chemically related interneuronal depressant drugs". J Pharmacol Exp Ther 122 (2): 239–246. PMID 13514612.

[Crankshaw_Raper_1968-4] Crankshaw DP, Raper C. (1968). "Some studies on peripheral actions of mephenesin, methocarbamol and diazepam". Br J Pharmacol 34 (3): 579–590. doi:10.1111/j.1476-5381.1968.tb08486.x. PMID 5726787.

[5] Methocarbamol. In: DRUGDEX System [intranet database]. Greenwood Village, Colorado: Thomson Healthcare; c1974–2009 [cited 2009 Feb 10].

[metabolismBruce1971-6] Bruce RB, Turnbull LB, Newman JH. (Jan 1971). "Metabolism of methocarbamol in the rat, dog, and human". J Pharm Sci 60 (1): 104–106. doi:10.1002/jps.2600600120. PMID 5548215.

[ESI-7] "New Drugs and Indications Reviewed at the May 2003 DEC Meeting" (PDF). ESI Canada. Retrieved 2008-11-14.

[Tylenol-8] "Tylenol Body Pain Night Overview and Dosage" (website). Tylenol Canada. Retrieved 2012-04-23.

[PubMed-9] "Subjective and behavioral effects of diphenhydramine, lorazepam and methocarbamol: evaluation of abuse liability". Journal of Pharmacology and Experimental Therapeutics. Retrieved 2011-05-06.

[10] -dictionary_thefreedictionary-methocarbamol

[11] Drugs.com-methocarbamol-side-effects

[12] METHOCARBAMOL – ORAL (Robaxin) side effects, medical uses, and drug interactions. Medicinenet.com. Retrieved on 2011-11-09.

[13] Methocarbamol: MedlinePlus Drug Information. Nlm.nih.gov. Retrieved on 2011-11-09.

[14] ttp://www.rxlist.com/robaxin-drug/indications-dosage.htm

[15] ttp://www.drugs.com/dosage/methocarbamol.html

[16] See NCQA’s HEDIS Measure: Use of High Risk Medications in the Elderly

[17] R.S. Murphey, U.S. Patent 2,770,649 (1956)

[18] Yale, H. L.; Pribyl, E. J.; Braker, W.; Bergeim, F. H.; Lott, W. A. (1950). "Muscle-relaxing Compounds Similar to 3-(o-Toloxy)-1,2-propanediol.1I. Aromatic Ethers of Polyhydroxy Alcohols and Related Compounds2,3". Journal of the American Chemical Society 72 (8): 3710. doi:10.1021/ja01164a107.

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methocarbamol