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| Clinical data | |
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| Trade names | Mexitil, NaMuscla |
| AHFS/Drugs.com | Monograph |
| MedlinePlus | a607064 |
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| Routes of administration | By mouth,intravenous |
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| Pharmacokinetic data | |
| Bioavailability | 90% |
| Protein binding | 50–60% |
| Metabolism | Liver (CYP2D6 and1A2-mediated) |
| Eliminationhalf-life | 10–12 hours |
| Excretion | Kidney (10%) |
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| CompTox Dashboard(EPA) | |
| ECHA InfoCard | 100.046.190 |
| Chemical and physical data | |
| Formula | C11H17NO |
| Molar mass | 179.263 g·mol−1 |
| 3D model (JSmol) | |
| Chirality | Racemic mixture |
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Mexiletine (INN; sold under the brand namesMexitil andNamuscla) is a medication used to treatabnormal 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-gatedsodium channel blocker and belongs to theClass IB group of anti-arrhythmic medications.[2]
Mexiletine has several uses including the treatment of abnormal heart rhythms orarrhythmias, chronic pain, andmyotonia.
In general when treating arrhythmias, mexiletine is reserved for use in dangerous heart rhythm disturbances such as ventricular tachycardia.[3] It is of particular use when treating arrhythmias caused by long QT syndrome.[4] 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.[4]
Mexiletine has been used to treat chronic pain and may also be used to treat muscle stiffness resulting frommyotonic dystrophy (Steinert's disease) or nondystrophic myotonias such asmyotonia congenita (Thomsen syndrome or Becker syndrome).[5][6]
Common side effects of mexiletine include abdominal pain, chest discomfort, drowsiness, headache, nausea and skin reactions.[7] Uncommon or rare side effects include seizures and liver dysfunction.[7]
Mexiletine is an oral analogue oflidocaine.[6] It is a class IBantiarrhythmic which shorten therefractory period and action potential duration (APD). Decrease in APD more than that of ERP so there is increase ERP/APD ratio.[3] The drug has a bioavailability of 90%, and peak plasma concentrations are seen after 2–4 hours.[3] The meandrug half-life is approximately 11 hours.[3] Mexiletine is predominantlymetabolised by theliver. Thepharmacokinetics of mexiletine are preserved with even moderate to severerenal impairment, but dose adjustment may be required whencreatinine clearance falls below 10 mL/minute.[3]
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.[9][10]
Mexiletine is available to veterinarians in the US for the treatment of heart disease in dogs.[medical citation needed] It is commonly used for the treatment ofarrhythmogenic right ventricular cardiomyopathy (ARVC) inBoxer dogs in combination withsotalol.[medical citation needed]
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