The heart's pumping action is controlled by electrical signals which pass through the heart muscle, causing contraction of the two pairs of heart chambers (left and right atria and ventricles). Mexiletine works by decreasing the sensitivity of heart muscle cells to electrical impulses, therefore slowing the electrical conduction in the heart muscle. 

What is it used for?

  • Irregular contraction of the ventricles, the two lower chambers of the heart (ventricular arrhythmias), that may be life threatening.

How does it work?

  • The heart's pumping action is controlled by electrical signals which pass through the heart muscle, causing contraction of the two pairs of heart chambers (left and right atria and ventricles). Mexiletine works by decreasing the sensitivity of heart muscle cells to electrical impulses, therefore slowing the electrical conduction in the heart muscle.
  • This helps to restore disturbances in heart rhythm (arrhythmias), which can seriously undermine the pumping action of the heart and result in inefficient blood circulation around the body.
  • Mexilitine is used to treat arrhythmias that arise in the ventricles of the heart, mainly after a heart attack.
It can be given in the form of tablets or by injection.

Important

  • Take this medicine with or after food.
  • This medicine may reduce the ability to drive or operate machinery safely, particularly if you drink alcohol while taking it.

Use with caution in

  • Decreased liver function
  • Defects of the heart's electrical message pathways, causing irregular heartbeats (heart conduction defects)
  • Heart failure
  • Loss of function of a natural pacemaker in the heart (sinus node dysfunction)
  • Low blood pressure (hypotension)
  • Moderate to severe liver disease
  • Parkinson's disease
  • Severely decreased kidney function
  • Slow heart rate (bradycardia)

Not to be used in

  • Allergy to local anaesthetics, eg lidocaine
  • Defect of the heart's electrical message pathways resulting in decreased function of the heart (heart block)
  • Failure of the heart to maintain adequate circulation of blood (cardiogenic shock)
  • This medicine should not be used if you are allergic to one or any of its ingredients. Please inform your doctor or pharmacist if you have previously experienced such an allergy.

If you feel you have experienced an allergic reaction, stop using this medicine and inform your doctor or pharmacist immediately.

Pregnancy and Breastfeeding

Certain medicines should not be used during pregnancy or breastfeeding. However, other medicines may be safely used in pregnancy or breastfeeding providing the benefits to the mother outweigh the risks to the unborn baby. Always inform your doctor if you are pregnant or planning a pregnancy, before using any medicine.

  • This medicine should be used with caution during pregnancy, and only if the expected benefit to the mother is greater than any possible risk to the foetus. Seek medical advice from your doctor.
  • This medicine passes into breast milk. Breastfeeding is not recommended when taking this medicine. Seek medical advice from your doctor.

Side effects

The following are some of the side effects that are known to be associated with this medicine. Because a side effect is stated here, it does not mean that all people using this medicine will experience that or any side effect.

  • Drowsiness
  • Confusion
  • Blood disorders
  • Disturbances of the gut such as diarrhoea, constipation, nausea, vomiting or abdominal pain
  • Abnormal heart beats (arrhythmias)
  • Low blood pressure (hypotension)
  • Seizures (convulsions)
  • Damage to the liver
  • Awareness of your heartbeat (palpitations)
  • Dizziness
  • Mood changes, strange or abnormal thoughts or depression
  • Slow heart rate (bradycardia)

The side effects listed above may not include all of the side effects reported by the drug's manufacturer.

For more information about any other possible risks associated with this medicine, please read the information provided with the medicine or consult your doctor or pharmacist.

How can this medicine affect other medicines?

  • There is a risk of decreased impulses within the heart (myocardial depression) when used with other anti-arrhythmic medicines.
  • When taken with propranolol or quinidine the effect of this medicine may be increased, with decreased side effects.
  • The blood levels of theophylline and caffeine are increased when taken with this medicine.
  • Atropine and opioid painkillers such as morphine slow the absorption of this medicine from the gut.
  • Metoclopramide speeds up the absorption of this medicine from the gut.
  • Rifampicin and phenytoin decrease the blood level of this medicine.

References:

https://www.netdoctor.co.uk/medicines/heart-blood/a7092/mexitil-discontinued-in-the-uk-july-2008/

https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=17&ved=2

https://www.aihw.gov.au/getmedia/f4f26d89-8e1a-4566-9754-a0f68391a6a6/mccda.pdf.aspx?inline=true

 

 

Health Reference: Heart disease