mexiletine mexiletine mexiletine (inn) (sold under the brand names mexitil and namuscla) is a medication used to treat abnormal heart rhythms, chronic pain, and some causes of muscle stiffness. common side effects include abdominal pain, chest discomfort, drowsiness, headache, and nausea. it works as a non-selective voltage-gated sodium channel blocker and belongs to the class ib group of anti-arrhythmic medications. mexiletineclinical datatrade namesmexitil, namusclaahfs/drugs.commonographmedlineplusa607064license data us dailymed: mexiletine pregnancycategory au: b1 routes ofadministrationby mouth, intravenousatc codec01bb02 (who) legal statuslegal status uk: pom (prescription only) us: ℞-only eu: rx-only pharmacokinetic databioavailability90%protein binding50–60%metabolismliver (cyp2d6 and 1a2-mediated)elimination half-life10–12 hoursexcretionkidney (10%)identifiers iupac name (rs)-1-(2,6-dimethylphenoxy)propan-2-amineor2-(2-aminopropoxy)-1,3-dimethylbenzene cas number31828-71-4 ypubchem cid4178iuphar/bps2629drugbankdb00379 ychemspider4034 yunii1u511hhv4zkeggd08215 yas hcl: d00639 ychebichebi:6916 ychemblchembl558 ycomptox dashboard (epa)dtxsid8048446 echa infocard100.046.190 chemical and physical dataformulac11h17nomolar mass179.263 g·mol−13d model (jsmol)interactive imagechiralityracemic mixture smiles o(c1c(cccc1c)c)cc(n)c inchi inchi=1s/c11h17no/c1-8-5-4-6-9(2)11(8)13-7-10(3)12/h4-6,10h,7,12h2,1-3h3 ykey:vlpiatfuuwwmkc-uhfffaoysa-n y (verify) medical uses mexiletine has several uses including the treatment of abnormal heart rhythms or arrhythmias, chronic pain, and myotonia. in general when treating arrhythmias, mexiletine is reserved for use in dangerous heart rhythm disturbances such as ventricular tachycardia. it is of particular use when treating arrhythmias caused by long qt syndrome. the lqt3 form of long qt syndrome is amenable to treatment with mexiletine as this form is caused by defective sodium channels that continue to release a sustained current rather than fully inactivating, however other forms of long qt syndrome can also be treated with this medication. mexiletine has been used to treat chronic pain and may also be used to treat muscle stiffness resulting from myotonic dystrophy (steinert's disease) or nondystrophic myotonias such as myotonia congenita (thomsen syndrome or becker syndrome). adverse effects common side effects of mexiletine include abdominal pain, chest discomfort, drowsiness, headache, nausea and skin reactions. uncommon or rare side effects include seizures and liver dysfunction. pharmacology mexiletine is an oral analogue of lidocaine. it is a class ib antiarrhythmic which shorten the refractory period and action potential duration (apd). decrease in apd more than that of erp so there is increase erp/apd ratio. the drug has a bioavailability of 90%, and peak plasma concentrations are seen after 2–4 hours. the mean drug half-life is approximately 11 hours. mexiletine is predominantly metabolised by the liver. the pharmacokinetics of mexiletine are preserved with even moderate to severe renal impairment, but dose adjustment may be required when creatinine clearance falls below 10 ml/minute. synthesis mexiletine synthesis: society and culture mexiletine is available for human use in the us, and has been reintroduced in the uk as a licensed product, having previously only been available as a 'named patient' import. the drug is sold under the trade name mexitil for use in arrhythmias and namuscla for use in myotonia. veterinary uses mexiletine is available to veterinarians in the us for the treatment of heart disease in dogs and cats. it is commonly used for the treatment of arrhythmogenic right ventricular cardiomyopathy (arvc) in boxer dogs in combination with sotalol.