metaxalone metaxalone 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. its exact mechanism of action is not known, but it may be due to general central nervous system depression. it is a moderately strong muscle relaxant, with relatively low incidence of side effects. metaxaloneclinical datatrade namesskelaxinahfs/drugs.commonographmedlineplusa682010license data us dailymed: metaxalone routes ofadministrationby mouthatc codenonelegal statuslegal status us: ℞-only pharmacokinetic databioavailabilityunknownmetabolismliverelimination half-life9.2 (± 4.8) hoursexcretionkidneyidentifiers iupac name 5--1,3-oxazolidin-2-one cas number1665-48-1 ypubchem cid15459iuphar/bps7609drugbankdb00660 ychemspider14709 yunii1nma9j598ykeggd00773 ychemblchembl1079604 ycomptox dashboard (epa)dtxsid3023269 echa infocard100.015.253 chemical and physical dataformulac12h15no3molar mass221.256 g·mol−13d model (jsmol)interactive image smiles o=c2oc(coc1cc(cc(c1)c)c)cn2 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) ykey:imwzzhhpurkass-uhfffaoysa-n y (verify) not to be confused with metolazone, a diuretic. common side effects include nausea, vomiting, drowsiness, and central nervous system (cns) side effects, such as dizziness, headache, and irritability. the metabolism of metaxalone involves enzymes cyp1a2 and cyp2c19 in the cytochrome p450 system. 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. because of the potential for side effects, this drug is considered a high risk in the elderly. pharmacokinetics metaxalone exhibits increased bioavailability when taken with food. 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%. 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. assay a literature survey reveals very few methods are reported for the determination of metaxalone to date. nirogi et al. 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. metaxalone has been used as an internal standard for few analytical methods.