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mexiletine

Namuscla · ATC code C01BB02

Also known as: Mexiletin

Key facts
Active substance
mexiletine
ATC code
C01BB02
Authorisation
centrally authorised across the EU (EMA)
Dosage forms
Namuscla 62 mg hard capsules / Namuscla 83 mg hard capsules / Namuscla 167 mg hard capsules
Marketing authorisation holder
Lupin Europe GmbH
Information as of
2026-10-27

Key facts

Mexiletine is a sodium channel blocker (class Ib antiarrhythmic). It is used for the symptomatic treatment of myotonia in non-dystrophic myotonic disorders.

What it is used for

  • Symptomatic treatment of myotonia in non-dystrophic myotonic disorders
  • Adults, adolescents aged 12 to 17 years and children aged 6 to 11 years weighing at least 20 kg

Dosing

  • Before starting: cardiological evaluation (ECG, Holter, echocardiography) and correction of electrolyte imbalance
  • Adults (Namuscla 167 mg): start 167 mg daily; after at least 1 week may increase to 333 mg, after a further week to 500 mg daily
  • Maintenance 167 mg to 500 mg daily; do not exceed 500 mg/day
  • Children and adolescents (6 to 17 years): weight-based dosing per the table in the full text (62 mg, 83 mg and 167 mg capsules)
  • Mild or moderate hepatic impairment: increase dose only after at least 2 weeks
  • Severe renal impairment: use not recommended

Contraindications

  • Hypersensitivity to mexiletine, excipients or any local anaesthetic
  • Ventricular tachyarrhythmia, complete heart block or heart block susceptible to progress
  • Acute or past myocardial infarction, symptomatic coronary artery disease
  • Heart failure with mid-range or reduced ejection fraction
  • Atrial tachyarrhythmia, fibrillation or flutter; sinus node dysfunction
  • Co-administration with medicines inducing torsades de pointes

Important warnings

  • May induce or worsen arrhythmia; cardiac monitoring before and during treatment, adapted to the heart condition
  • DRESS (drug reaction with eosinophilia and systemic symptoms), which can be fatal
  • Close ECG monitoring with dose changes or co-medication affecting cardiac conduction

Side effects

  • Most common: abdominal pain (12%), insomnia (12%) and vertigo (8%)
  • Common: somnolence, headache, paraesthesia, blurred vision, tachycardia, nausea, hypotension, acne
  • Most serious: DRESS and arrhythmia (atrioventricular block, ventricular fibrillation)
  • Very rare: drug-induced liver injury, hepatitis

Interactions

  • Antiarrhythmics inducing torsades de pointes (class Ia, Ic, III): contraindicated
  • Other antiarrhythmics (class Ib, II, IV, e.g. beta-blockers, verapamil, diltiazem): not recommended
  • CYP1A2 or CYP2D6 inhibitors (e.g. ciprofloxacin, fluvoxamine, propafenone, quinidine) increase mexiletine exposure; ECG monitoring and dose adaptation may be needed
  • Enzyme inducers (e.g. omeprazole, phenytoin, rifampicin) may alter concentrations

Pregnancy and breastfeeding

  • Pregnancy: mexiletine crosses the placenta; as a precaution, preferable to avoid
  • Breast-feeding: excreted in human milk; decide between breast-feeding and therapy based on benefit

Summary of the official product information, written with AI (Claude, Anthropic) on 2026-10-28. Every number was checked automatically against the original text. Not reviewed by a physician – the full official text is authoritative.

Full official text →

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For patients

Package leaflet, verbatim

Package leaflet for patients →

Authorisation and brand names by country

Medicines with exactly this active-substance composition, as listed in the national registers – alphabetical and without ranking. Whether a product is currently available is not shown here.

EU – centrally authorised (all member states)

  • NamusclaLupin Europe GmbH · EMEA/H/C/004584

Source: European Medicines Agency (EMA), product information

Germany

  • ZunmyroClinigen Healthcare B.V. · 3 register entries

Source: EMA – Article 57 product data (EU/EEA), as of 2026-10-28

Brand names in 6 more European countries
Denmark
Dopital
Finland
Dopital
France
Makmorsa
Hungary
Ritalmex
Norway
Dopital
Sweden
Dopital

EMA – Article 57 product data (EU/EEA), 2026-10-28

Medelix receives no money from pharmaceutical companies. Brand names are listed alphabetically and without ranking.

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Sources

  1. European Medicines Agency. Namuscla – EPAR, Product Information (OF THE TEXT Detailed information on this medicinal product i). 2026-10-27. https://www.ema.europa.eu/en/documents/product-information/namuscla-epar-product-information_en.pdf
  2. EMA – Article 57 product data (EU/EEA), 2026-10-28. https://www.ema.europa.eu/en/human-regulatory-overview/post-authorisation/data-medicines-iso-idmp-standards-post-authorisation/public-data-article-57-database

Editorial: Medelix editorial team · last updated 2026-10-27 · How these pages are made · Report an error

Source: European Medicines Agency (EMA), product information. Not advertising, not a treatment recommendation. For questions about your own treatment, ask your doctor or pharmacist.