You are using an unsupported browser. Please upgrade your browser to a newer version to get the best experience on DrugBank.
Identification
NameMetaxalone
Accession NumberDB00660  (APRD00514)
TypeSmall Molecule
GroupsApproved
Description

Metaxalone (marketed by King Pharmaceuticals under the brand name Skelaxin®) is a muscle relaxant used to relax muscles and relieve pain caused by strains, sprains, and other musculoskeletal conditions. Its exact mechanism of action is not known, but it may be due to general central nervous system depression. It is considered to be a moderately strong muscle relaxant, with relatively low incidence of side effects. Skelaxin comes in an 800 mg scored tablet. It previously came in both 400 mg and 800 mg tablets. The 400 mg tablet has been discontinued. Possible side effects include nausea, vomiting, drowsiness and CNS side effects such as dizziness, headache, and irritability.

Structure
Thumb
Synonyms
Metassalone
Metaxalon
Metaxalona
Metaxalonum
Skelaxin
External Identifiers
  • AHR 438
Approved Prescription Products
NameDosageStrengthRouteLabellerMarketing StartMarketing End
Metaxalonetablet800 mg/1oralNorthwind Pharmaceuticals2014-04-01Not applicableUs
Metaxalonetablet800 mg/1oralBlenheim Pharmacal, Inc.2010-05-20Not applicableUs
Metaxalonetablet800 mg/1oralRebel Distributors Corp2007-11-01Not applicableUs
Metaxalonetablet800 mg/1oralbryant ranch prepack2007-11-01Not applicableUs
Metaxalonetablet800 mg/1oralUnit Dose Services2007-11-01Not applicableUs
Metaxalonetablet800 mg/1oralSt. Marys Medical Park Pharmacy2011-01-30Not applicableUs
Metaxalonetablet800 mg/1oralLake Erie Medical & Surgical Supply DBA Quality Care Products LLC2011-12-06Not applicableUs
Metaxalonetablet800 mg/1oralbryant ranch prepack2007-11-01Not applicableUs
Metaxalonetablet800 mg/1oralPreferred Pharmaceuticals, Inc.2014-02-14Not applicableUs
Metaxalonetablet800 mg/1oralDIRECT RX2014-01-01Not applicableUs
Metaxalonetablet800 mg/1oralREMEDYREPACK INC.2012-03-29Not applicableUs
Metaxalonetablet800 mg/1oralSTAT Rx USA LLC2007-11-01Not applicableUs
Metaxalonetablet800 mg/1oralPd Rx Pharmaceuticals, Inc.2007-11-01Not applicableUs
Metaxalonetablet800 mg/1oralDispensing Solutions, Inc.2007-11-01Not applicableUs
Metaxalonetablet800 mg/1oralPd Rx Pharmaceuticals, Inc.2007-11-01Not applicableUs
Metaxalonetablet800 mg/1oralCarilion Materials Management2007-11-01Not applicableUs
Metaxalonetablet800 mg/1oralH.J. Harkins Company, Inc.2007-11-01Not applicableUs
Metaxalonetablet800 mg/1oralSTAT Rx USA LLC2007-11-01Not applicableUs
Metaxalonetablet800 mg/1oralCore Pharma, Llc2007-11-01Not applicableUs
Skelaxintablet800 mg/1oralPhysicians Total Care, Inc.2003-01-30Not applicableUs
Skelaxintablet800 mg/1oralLake Erie Medical & Surgical Supply DBA Quality Care Products LLC2011-12-14Not applicableUs
Skelaxintablet800 mg/1oralRebel Distributors Corp1962-08-13Not applicableUs
Skelaxintablet800 mg/1oralPreferred Pharmaceuticals, Inc2003-01-30Not applicableUs
Skelaxintablet800 mg/1oralPfizer Laboratories Div Pfizer Inc2002-08-30Not applicableUs
Skelaxintablet800 mg/1oralSTAT Rx USA LLC2002-08-30Not applicableUs
Skelaxintablet800 mg/1oralPd Rx Pharmaceuticals, Inc.2002-08-30Not applicableUs
Skelaxintablet800 mg/1oralBlenheim Pharmacal, Inc.2010-03-15Not applicableUs
Skelaxintablet800 mg/1oralCardinal Health2002-08-30Not applicableUs
Approved Generic Prescription Products
NameDosageStrengthRouteLabellerMarketing StartMarketing End
Metaxalltablet800 mg/1oralSircle Laboratories, Llc2015-09-25Not applicableUs
Metaxalonetablet800 mg/1oralAmneal Pharmaceuticals, LLC2013-05-31Not applicableUs
Metaxalonetablet800 mg/1oralEon Labs, Inc.2010-03-31Not applicableUs
Metaxalonetablet800 mg/1oralAmerican Health Packaging2013-12-18Not applicableUs
Metaxalonetablet800 mg/1oralNorthwind Pharmaceuticals2014-02-12Not applicableUs
Metaxalonetablet800 mg/1oralProficient Rx LP2013-05-31Not applicableUs
Metaxalonetablet800 mg/1oralAv Pak2015-03-13Not applicableUs
Metaxalonetablet800 mg/1oralDIRECT RX2015-01-01Not applicableUs
Metaxalonetablet800 mg/1oralAv Kare, Inc.2015-05-22Not applicableUs
Metaxalonetablet400 mg/1oralCore Pharma, Llc2015-03-31Not applicableUs
Metaxalonetablet800 mg/1oralGemini Laboratories, LLC2015-12-30Not applicableUs
Metaxalonetablet800 mg/1oralAidarex Pharmaceuticals LLC2013-05-31Not applicableUs
Metaxalonetablet800 mg/1oralClinical Solutions Wholesale2013-05-31Not applicableUs
Metaxalonetablet800 mg/1oralRebel Distributors Corp.2010-03-31Not applicableUs
Metaxalonetablet800 mg/1oralPreferred Pharmaceuticals, Inc.2015-01-06Not applicableUs
Metaxalonetablet800 mg/1oralPhysicians Total Care, Inc.2010-04-07Not applicableUs
Metaxalonetablet800 mg/1oralBlue Point Laboratories2014-04-22Not applicableUs
Metaxalonetablet800 mg/1oralBlenheim Pharmacal, Inc.2013-09-11Not applicableUs
Metaxalonetablet800 mg/1oralKeltman Pharmaceuticals Inc.2008-06-25Not applicableUs
Metaxalonetablet800 mg/1oralAmneal Pharmaceuticals of New York, LLC2013-05-31Not applicableUs
Approved Over the Counter ProductsNot Available
Unapproved/Other Products Not Available
International BrandsNot Available
Brand mixturesNot Available
SaltsNot Available
Categories
UNII1NMA9J598Y
CAS number1665-48-1
WeightAverage: 221.2524
Monoisotopic: 221.105193351
Chemical FormulaC12H15NO3
InChI KeyInChIKey=IMWZZHHPURKASS-UHFFFAOYSA-N
InChI
InChI=1S/C12H15NO3/c1-8-3-9(2)5-10(4-8)15-7-11-6-13-12(14)16-11/h3-5,11H,6-7H2,1-2H3,(H,13,14)
IUPAC Name
5-(3,5-dimethylphenoxymethyl)-1,3-oxazolidin-2-one
SMILES
CC1=CC(OCC2CNC(=O)O2)=CC(C)=C1
Taxonomy
DescriptionThis compound belongs to the class of organic compounds known as phenol ethers. These are aromatic compounds containing an ether group substituted with a benzene ring.
KingdomOrganic compounds
Super ClassBenzenoids
ClassBenzene and substituted derivatives
Sub ClassPhenol ethers
Direct ParentPhenol ethers
Alternative Parents
Substituents
  • Phenol ether
  • Alkyl aryl ether
  • Oxazolidinone
  • Oxazolidine
  • Oxacycle
  • Azacycle
  • Organoheterocyclic compound
  • Monocarboxylic acid or derivatives
  • Ether
  • Hydrocarbon derivative
  • Organooxygen compound
  • Organonitrogen compound
  • Aromatic heteromonocyclic compound
Molecular FrameworkAromatic heteromonocyclic compounds
External DescriptorsNot Available
Pharmacology
IndicationFor the treatment of painful peripheral musculoskeletal conditions and spasticity from upper motor neuron syndromes.
PharmacodynamicsMetaxalone is a skeletal muscle relaxant indicated as an adjunct to rest, physical therapy, and other measures for the relief of discomforts 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. Metaxalone does not directly relax tense skeletal muscles in man.
Mechanism of actionThe mechanism of action of metaxalone in humans has not been established, but may be due to general central nervous system depression.
Related Articles
AbsorptionThe absolute bioavailability of metaxalone from Skelaxin tablets is not known.
Volume of distribution
  • 800 L
Protein bindingNot Available
Metabolism

Probably hepatic.

Route of eliminationMetaxalone is metabolized by the liver and excreted in the urine as unidentified metabolites.
Half life9.2 (+/- 4.8) hours
Clearance
  • 68 +/- 50 L/h [Subjects received 1×400mg tablet under fasted conditions]
  • 66 +/- 51 L/h [Subjects received 2×400 mg tablets under fasted conditions]
ToxicityLD50=775mg/kg (Rat, oral); LD50=1690 mg/kg (Mouse, oral). When determining the LD50 in rats and mice, progressive sedation, hypnosis and finally respiratoryfailure were noted as the dosage increased. In dogs, no LD50 could be determined as the higher doses produced an emetic action in 15 to 30 minutes.
Affected organisms
  • Humans and other mammals
PathwaysNot Available
SNP Mediated EffectsNot Available
SNP Mediated Adverse Drug ReactionsNot Available
ADMET
Predicted ADMET features
PropertyValueProbability
Human Intestinal Absorption+1.0
Blood Brain Barrier+0.9747
Caco-2 permeable+0.5076
P-glycoprotein substrateNon-substrate0.7072
P-glycoprotein inhibitor INon-inhibitor0.8309
P-glycoprotein inhibitor IINon-inhibitor0.906
Renal organic cation transporterNon-inhibitor0.8464
CYP450 2C9 substrateNon-substrate0.8154
CYP450 2D6 substrateNon-substrate0.7182
CYP450 3A4 substrateNon-substrate0.5649
CYP450 1A2 substrateInhibitor0.6863
CYP450 2C9 inhibitorNon-inhibitor0.7448
CYP450 2D6 inhibitorNon-inhibitor0.7733
CYP450 2C19 inhibitorNon-inhibitor0.6471
CYP450 3A4 inhibitorNon-inhibitor0.911
CYP450 inhibitory promiscuityHigh CYP Inhibitory Promiscuity0.797
Ames testNon AMES toxic0.6074
CarcinogenicityNon-carcinogens0.9312
BiodegradationNot ready biodegradable0.9544
Rat acute toxicity2.4250 LD50, mol/kg Not applicable
hERG inhibition (predictor I)Weak inhibitor0.9319
hERG inhibition (predictor II)Non-inhibitor0.913
ADMET data is predicted using admetSAR, a free tool for evaluating chemical ADMET properties. (23092397 )
Pharmacoeconomics
Manufacturers
  • Sandoz inc
  • King pharmaceuticals inc
  • Elan Corporation
Packagers
Dosage forms
FormRouteStrength
Tabletoral400 mg/1
Tabletoral800 mg/1
Prices
Unit descriptionCostUnit
Metaxalone 800 mg tablet3.88USD tablet
Skelaxin 800 mg tablet3.84USD tablet
Skelaxin 400 mg tablet0.84USD tablet
DrugBank does not sell nor buy drugs. Pricing information is supplied for informational purposes only.
Patents
Patent NumberPediatric ExtensionApprovedExpires (estimated)
US6407128 No2001-12-032021-12-03Us
US7122566 No2006-02-062026-02-06Us
US7714006 No2001-12-032021-12-03Us
Properties
StateSolid
Experimental Properties
PropertyValueSource
melting point122 °CPhysProp
logP2.3Not Available
Predicted Properties
PropertyValueSource
Water Solubility1.28 mg/mLALOGPS
logP1.63ALOGPS
logP2.37ChemAxon
logS-2.2ALOGPS
pKa (Strongest Acidic)13.14ChemAxon
pKa (Strongest Basic)-4.9ChemAxon
Physiological Charge0ChemAxon
Hydrogen Acceptor Count2ChemAxon
Hydrogen Donor Count1ChemAxon
Polar Surface Area47.56 Å2ChemAxon
Rotatable Bond Count3ChemAxon
Refractivity59.32 m3·mol-1ChemAxon
Polarizability23.74 Å3ChemAxon
Number of Rings2ChemAxon
Bioavailability1ChemAxon
Rule of FiveYesChemAxon
Ghose FilterYesChemAxon
Veber's RuleYesChemAxon
MDDR-like RuleYesChemAxon
Spectra
Mass Spec (NIST)Not Available
SpectraNot Available
References
Synthesis Reference

Spiridon Spireas, “Bioavailable compositions of metaxalone and processes for producing the same.” U.S. Patent US20050276844, issued December 15, 2005.

US20050276844
General References
  1. See S, Ginzburg R: Choosing a skeletal muscle relaxant. Am Fam Physician. 2008 Aug 1;78(3):365-70. [PubMed:18711953 ]
  2. Elenbaas JK: Centrally acting oral skeletal muscle relaxants. Am J Hosp Pharm. 1980 Oct;37(10):1313-23. [PubMed:6999895 ]
External Links
ATC CodesNot Available
AHFS CodesNot Available
PDB EntriesNot Available
FDA labelDownload (124 KB)
MSDSNot Available
Interactions
Drug Interactions
Drug
AzelastineMetaxalone may increase the central nervous system depressant (CNS depressant) activities of Azelastine.
BaclofenThe risk or severity of adverse effects can be increased when Baclofen is combined with Metaxalone.
BrimonidineBrimonidine may increase the central nervous system depressant (CNS depressant) activities of Metaxalone.
BuprenorphineMetaxalone may increase the central nervous system depressant (CNS depressant) activities of Buprenorphine.
DoxylamineDoxylamine may increase the central nervous system depressant (CNS depressant) activities of Metaxalone.
DronabinolDronabinol may increase the central nervous system depressant (CNS depressant) activities of Metaxalone.
DroperidolDroperidol may increase the central nervous system depressant (CNS depressant) activities of Metaxalone.
EthanolMetaxalone may increase the central nervous system depressant (CNS depressant) activities of Ethanol.
HydrocodoneMetaxalone may increase the central nervous system depressant (CNS depressant) activities of Hydrocodone.
HydroxyzineHydroxyzine may increase the central nervous system depressant (CNS depressant) activities of Metaxalone.
LorazepamThe risk or severity of adverse effects can be increased when Lorazepam is combined with Metaxalone.
Magnesium SulfateMagnesium Sulfate may increase the central nervous system depressant (CNS depressant) activities of Metaxalone.
MethotrimeprazineMetaxalone may increase the central nervous system depressant (CNS depressant) activities of Methotrimeprazine.
MetyrosineMetaxalone may increase the sedative activities of Metyrosine.
MinocyclineMinocycline may increase the central nervous system depressant (CNS depressant) activities of Metaxalone.
MirtazapineMetaxalone may increase the central nervous system depressant (CNS depressant) activities of Mirtazapine.
NabiloneNabilone may increase the central nervous system depressant (CNS depressant) activities of Metaxalone.
OrphenadrineMetaxalone may increase the central nervous system depressant (CNS depressant) activities of Orphenadrine.
ParaldehydeMetaxalone may increase the central nervous system depressant (CNS depressant) activities of Paraldehyde.
ParoxetineThe risk or severity of adverse effects can be increased when Metaxalone is combined with Paroxetine.
PerampanelPerampanel may increase the central nervous system depressant (CNS depressant) activities of Metaxalone.
PramipexoleMetaxalone may increase the sedative activities of Pramipexole.
RopiniroleMetaxalone may increase the sedative activities of Ropinirole.
RotigotineMetaxalone may increase the sedative activities of Rotigotine.
RufinamideThe risk or severity of adverse effects can be increased when Rufinamide is combined with Metaxalone.
Sodium oxybateSodium oxybate may increase the central nervous system depressant (CNS depressant) activities of Metaxalone.
SuvorexantMetaxalone may increase the central nervous system depressant (CNS depressant) activities of Suvorexant.
TapentadolTapentadol may increase the central nervous system depressant (CNS depressant) activities of Metaxalone.
ThalidomideMetaxalone may increase the central nervous system depressant (CNS depressant) activities of Thalidomide.
ZolpidemMetaxalone may increase the central nervous system depressant (CNS depressant) activities of Zolpidem.
Food InteractionsNot Available
Comments
comments powered by Disqus
Drug created on June 13, 2005 07:24 / Updated on July 29, 2016 01:51