Active Ingredients

Flecainide – Effect, Application & Risks


The active ingredient flecainide is classified as an antiarrhythmic . It is used to treat cardiac arrhythmias .

What is flecainide?

Flecainide is an antiarrhythmic used to treat abnormal heart rhythms. The drug was discovered in the 1970s. It was approved in Europe in 1982.

In Germany, the prescription-only active ingredient came onto the market under the trade names Flecagamma® and Tambocor®. Flecainide went off-patent in 2004. After that, various generics containing the drug were offered in Germany.

Flecainide has the disadvantage that it can itself cause cardiac arrhythmias. This happens primarily through interactions with other drugs or too high a dosage.

Pharmacological effect on body & organs

Flecainide belongs to the class Ic antiarrhythmic drug group. As a result, the drug works in the same way as the other antiarrhythmic drugs in this group.

The human heart consists of a chamber (ventricle) and an atrium ( atrium ) on both sides. From there, the blood is pumped out via a valve mechanism .

The heart rhythm originates within the sinus node of the right atrium. Special pacemaker cells are located there, the function of which is to clock the heart’s pumping speed. First, they allow the two atria to contract. This is followed by the two chambers of the heart.

A cardiac arrhythmia occurs either in the ventricle or in the atrium. It can also affect both structures at the same time. When the heart beats too hard, which doctors call tachycardia , it contracts so quickly that it is unable to pump blood effectively.

This is where flecainide comes into play. The active ingredient achieves a reduction in the conduction speed of the stimulus conductors of the sinus node. The impulse for the tachycardia comes either from the ventricle or from the atrium.

Flecainide is a sodium channel blocker. This means that the active substance prevents the supply of sodium ions. As a result, no further action potentials can form, which leads to a dampening of heart muscle activity. In this way, the heart rate can be slowed down .

Flecainide works quickly, so there is no need to convert the active substance within the body. Since the organism can access the full dose of the drug, the patient’s condition improves quickly. Flecainide is therefore also suitable for the treatment of life-threatening cardiac arrhythmias.

Once ingested, flecainide is rapidly absorbed into the blood through the intestines . The highest concentration occurs after about three hours. The breakdown of the active substance takes place in the liver . It is eliminated from the body with the urine via the kidneys . After about 20 hours, only about 50 percent of the drug is still in the body.

Medicinal Application & Use for Treatment & Prevention

Flecainide is used to treat special forms of cardiac arrhythmias. These are supraventricular tachyarrhythmias that can be life-threatening. An irregular and rapid heartbeat due to tachycardic supraventricular cardiac arrhythmias such as tachycardia also belongs to the areas of application of the active ingredient . This emanates from the AV node of the heart and is referred to in medicine as AV junctional tachycardia.

Other indications are paroxysmal atrial fibrillation and supraventricular tachycardia in WPW syndrome . In addition to the treatment of cardiac arrhythmias, flecainide is also suitable for their prevention.

The drug is taken in the form of tablets. The patient takes it with water during or after a meal. The usual dosage is 50 to 100 grams of flecainide twice a day. If the patient weighs more or if there is a special case, up to 400 milligrams per day can also be administered. As a rule, treatment starts insidiously with a low dose, which gradually increases over time. As a result of this procedure, the patients tolerate the drug better and suffer less frequently from side effects .

Risks & side effects

Taking flecainide can be associated with undesirable side effects. These primarily include visual disturbances , dizziness and balance disorders . In addition, around 10 out of 100 patients experience headaches , sleep problems , anxiety , depression , sensory disorders such as tingling , tremors , tiredness , rashes and reddening of the skin, feelings of weakness , tinnitus , nausea ,vomiting , breathing difficulties , water retention , constipation and cardiac arrhythmia.

Other side effects can include abdominal pain , gastrointestinal problems , unsteadiness when walking , movement disorders , increased sweating , drowsiness , diarrhea , a refusal to eat and fever .

In rare cases, those affected also suffer from hives , hair loss , nerve disorders in the limbs, memory problems , convulsions , pneumonia and confusion or delusions . Most side effects occur early in treatment and improve over time. In some cases, reducing the dose also helps.

If the patient is hypersensitive to flecainide, if there is limited cardiac output or a blockage in the excitation line within the atrium , the antiarrhythmic drug must not be taken. An exception is life-threatening ventricular cardiac arrhythmia.

Taking other drugs that affect the heart can also be problematic. These are primarily cardiac glycosides such as digitoxin or digoxin , beta blockers such as bisoprolol or metoprolol , and calcium blockers such as verapamil . If they have to be taken at the same time, it may make sense to reduce the flecainide dose.

In addition, regular ECG checks should be carried out. Pregnant and breastfeeding women should not take flecainide. The same applies to children under the age of 12.

Lisa Newlon
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Hello! I am Lisa Newlon, and I am a medical writer and researcher with over 10 years of experience in the healthcare industry. I have a Master’s degree in Medicine, and my deep understanding of medical terminology, practices, and procedures has made me a trusted source of information in the medical world.