How does it work?
Arythmol tablets contain the active ingredient propafenone, which is a type of medicine called an anti-arrhythmic.
The heart's pumping action is controlled by electrical signals that pass through the heart muscle. The electrical signals causes the two pairs of heart chambers (left and right atria and ventricles) to contract in a regular manner that produces the heartbeat. If the electrical activity in the heart is disturbed for any reason, irregular heartbeats (arrhythmias) of various types can result. These can seriously undermine the pumping action of the heart and result in inefficient blood circulation around the body.
Propafenone helps to treat arrhythmias by decreasing the sensitivity of the heart muscle cells to electrical impulses. This slows and regulates the electrical conduction in the heart muscle, which helps to restore disturbances in the heart rhythm.
Propafenone also blocks beta receptors in the heart, which causes a decrease in heart rate and helps in the control of arrhythmias.
What is it used for?
- To correct and prevent irregular heartbeats that start in the lower chambers of the heart (ventricular arrhythmias).
- To correct and prevent an abnormal heart rhythm where the heart sporadically beats very rapidly, as a result of problems with the electrical message pathways in the top part of the heart (paroxysmal supraventricular tachyarrhythmias). This includes atrial flutter, atrial fibrillation and rapid heartbeats caused by an additional electrical signal in or near the AV node. Arythmol tablets are used when other treatments have been unsuccessful or are not suitable.
How do I take it?
- Arythmol tablets should be swallowed whole with a drink of water. They should be taken with or after food.
- The amount taken and how often varies from person to person, and according to the type of arrhythmia you have. It is important to follow the instructions given by your doctor and printed on the dispensing label.
- Before treatment with this medicine is started your doctor will want you to have a blood test to check your liver and kidney function, so that the correct dose of the medicine can be prescribed. The levels of electrolytes such as sodium, potassium or magnesium in your blood will also be checked and your doctor will correct any problems before starting treatment.
- This medicine may reduce your ability to drive or operate machinery safely. Do not drive or operate machinery until you know how this medicine affects you and you are sure it won't affect your performance.
- Most medicines that control abnormal heart rhythms can also provoke them in some circumstances. For this reason, if you feel like your heart condition has got worse or your heartbeat changes, gets faster or slower, or starts to pound, or you experience chest pain, shortness of breath or feeling faint, it is important to consult your doctor straight away.
Use with caution in
- Elderly people.
- Chronic obstructive pulmonary disease (COPD).
- Heart failure.
- People with an enlarged heart.
- Structural heart disease.
- People who have an artificial pacemaker.
- Decreased kidney function.
- Decreased liver function.
Not to be used in
- Failure of the heart to maintain adequate circulation (cardiogenic shock), except when this is due to arrhythmias.
- People with abnormal electrical conduction in the top chambers (atria) of the heart, unless a pacemaker is fitted.
- People with severe electrical conduction disturbances within the heart (heart block), unless a pacemaker is fitted.
- People whose irregular heartbeat is related to a problem with the sinus node in their heart (sinus node dysfunction), unless a pacemaker is fitted.
- Uncontrolled heart failure.
- Very slow heart rate (severe bradycardia).
- Very low blood pressure (severe hypotension).
- Uncontrolled disturbances in the levels of electrolytes such as potassium, magnesium or sodium in the blood.
- Abnormal muscle weakness (myasthenia gravis).
- Severe chronic obstructive pulmonary disease (COPD).
- People taking the HIV medicine ritonavir.
This medicine should not be used if you are allergic to 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.
- The safety of this medicine during pregnancy has not been established. It should not be used during pregnancy.
- There is no information available about the use of this medicine in breastfeeding mothers. It should not be used by women who are breastfeeding. Seek medical advice from your doctor.
- This medicine should be taken with or after food.
- This medication is to be swallowed whole, not chewed.
Medicines and their possible side effects can affect individual people in different ways. The following are some of the side effects that are known to be associated with this medicine. Just because a side effect is stated here, it does not mean that all people using this medicine will experience that or any side effect.
- Disturbances of the gut such as diarrhoea, constipation, nausea, vomiting, or abdominal pain.
- Bitter taste in the mouth or dry mouth.
- Loss of appetite.
- A drop in blood pressure that occurs when going from lying down to sitting or standing, which results in dizziness and lightheadedness (postural hypotension).
- Skin reactions such as redness, rash, itching.
- Chest pain.
- Sleep disturbances.
- Pins and needles sensations.
- Blurred vision.
- Blockade of the electrical pathways in the heart (heart block).
- Slow heart rate (bradycardia).
- Worsening of heart condition or new irregular heartbeats - see warning section above.
- Problems with the liver such as hepatitis.
- Yellowing of the skin and whites of the eyes (jaundice).
- Lupus syndrome (with symptoms such as facial rash, joint pain, muscle pain and fever).
- Decreased ability of men to perform sexual intercourse and decreased sperm count, reversible on stopping treatment.
The side effects listed above may not include all of the side effects reported by the medicine'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?
It is important to tell your doctor or pharmacist what medicines you are already taking, including those bought without a prescription and herbal medicines, before you start treatment with this medicine. Similarly, check with your doctor or pharmacist before taking any new medicines while taking this one, to ensure that the combination is safe.
There may be an increased risk of the heart beating too slowly if any of the following medicines are used in combination with propafenone:
- other anti-arrhythmic medicines such as amiodarone
- beta-blockers such as atenolol, propranolol
- calcium channel blockers such as verapamil
- tricyclic antidepressants such as amitriptyline.
If you are taking digoxin for heart disease your doctor may want you to have regular blood tests to monitor the level of digoxin in your blood during treatment with this medicine. This is because propafenone may increase the amount of digoxin in the blood.
This medicine can increase the blood level and enhance the anti-blood-clotting effect of the anticoagulant medicine warfarin. Your doctor may want to check your blood clotting time (INR) more frequently if you are taking propafenone with warfarin.
Propafenone may also increase the blood levels of the following medicines:
- beta-blockers such as metoprolol, propranolol
The following medicines may decrease the amount of propafenone in your blood, which could make it less effective:
The following medicines may increase the amount of propafenone in the blood,which may increase the risk of its side effects unless your propafenone dose is reduced:
- mizolastine (not recommended in combination with propafenone)
- protease inhibitors for HIV infection, eg ritonavir, fosamprenavir (if you are taking a protease inhibitor, particularly ritonavir, propafenone is not recommended for you)
- selective serotonin re-uptake inhibitor antidepressants (SSRIs) such as fluoxetine, paroxetine.
Other medicines containing the same active ingredient
There are currently no other medicines available in the UK that contain propafenone as the active ingredient.