Metaxalone
Muscle relaxant
From Wikipedia, the free encyclopedia
Metaxalone, sold under the brand name Skelaxin, is a muscle relaxant medication used to relax muscles and relieve pain caused by strains, sprains, and other musculoskeletal conditions.[1] Its exact mechanism of action is not known, but it may be due to general central nervous system depression.[1] It is a moderately strong muscle relaxant, with relatively low incidence of side effects.[citation needed]
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| Trade names | Skelaxin |
| AHFS/Drugs.com | Monograph |
| MedlinePlus | a682010 |
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| Routes of administration | By mouth |
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| Bioavailability | Unknown |
| Metabolism | Liver |
| Elimination half-life | 9.2 ± 4.8 hours |
| Excretion | Kidney |
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| ECHA InfoCard | 100.015.253 |
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| Formula | C12H15NO3 |
| Molar mass | 221.256 g·mol−1 |
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Common side effects include nausea, vomiting, drowsiness, and central nervous system (CNS) side effects, such as dizziness, headache, and irritability.[1]
The metabolism of metaxalone involves enzymes CYP1A2 and CYP2C19 in the cytochrome P450 system. [medical citation needed] Because many medications are metabolized by enzymes in this system, precaution must be taken when administering it with other medications involving the P450 system to avoid interactions.[2]
Because of the potential for side effects, this drug is considered high risk in the elderly.[medical citation needed]
Pharmacokinetics
Metaxalone exhibits increased bioavailability when taken with food.[3] Specifically, in one study, compared to fasted conditions, the presence of food at the time of drug administration increased Cmax by 77.5%, AUC0-t by 23.5%, and AUC0-∞ by 15.4%.[4] Metaxalone is a substrate of CYP1A2 and CYP2C19, an inhibitor of CYP1A2, CYP2B6, CYP2C9, CYP2C19, CYP2D6, CYP2E1, and CYP3A, and an inducer of CYP1A2 and CYP3A4.[2]
Assay
A literature survey reveals very few methods are reported for the determination of metaxalone to date. Nirogi et al.[4] reported a liquid chromatographic method coupled to tandem mass spectrometry for the quantification of metaxalone in human plasma. A stability-indicating HPLC method was introduced by P. K. Sahu et al.[5] Metaxalone has been used as an internal standard for few analytical methods.[6][7]
