Antiarrhythmics (singular: antiarrhythmic) is the medical term for drugs against cardiac arrhythmia. The classification of these pharmaceuticals is officially divided into 4 classes. The criterion here is the physiological mechanism of action.

Some antiarrhythmic drugs act at multiple points in the metabolism, which is why their assignment in the system is difficult. Therefore, the classification is also under discussion, especially since unofficial representations call a 5th class. This is where antiarrhythmics that do not appear in the official version belong. In addition, the four classes only contain drugs against rapid cardiac arrhythmia (tachycardia).

Although slow cardiac arrhythmias (bradycardia) can also be treated with some drugs, these pharmaceuticals are not included in the standard definition. These agents play a subordinate role because slow cardiac arrhythmias are compensated predominantly with cardiac pacemakers and not with antiarrhythmics.

Application, effect & use

Class I antiarrhythmics are the sodium channel blockers. They reduce the influx of sodium into the heart muscle cells. Sodium is crucial for the development of action potentials (electrical excitation). There are 3 groups of sodium blockers, which differ in their fine effect on the action potential, but which all have a direct dampening effect on the heart muscle cells.

Class II antiarrhythmics are known beta-receptor blockers, or beta- blockers for short . These drugs affect the heart’s own nerve complex. Here they block the beta-adrenoceptors, which are signal points on the nerve cells that are stimulated by the stress hormone adrenaline. As a result, the heart reacts less to hormonal stimulation and works more evenly.

Class III are the potassium channel blockers. Potassium is also involved in the build-up of excitation in the heart muscle cell. The potassium channel blockers slow down the flow of the mineral out of the cell, causing each heartbeat to slow down. This also results in a more regular heartbeat. Class IV antiarrhythmics include calcium channel blockers. The pharmaceuticals reduce the uptake of calcium at the nerve cells of the coronary clock generator. The reduced nervous performance results in a reduced heart rate.

Finally, there are the unclassified antiarrhythmics, which include potassium and magnesium , for example . The minerals are necessary for the function of the nerve and muscle cells and can positively support the treatment of cardiac arrhythmias in patients with corresponding deficiency symptoms. Cardiac glycosides also belong to this “fringe group” of antiarrhythmics. They cause stronger contractions of the heart muscle with a simultaneously reduced heart rate. Atropine is one of the few drugs given for rapid cardiac arrhythmia. The active substance blocks certain receptors on nerve cells like other antiarrhythmic drugs.

Herbal, natural & pharmaceutical antiarrhythmics

For the most part, antiarrhythmics are substances that are manufactured synthetically and do not occur naturally. Some also come from the secondary metabolism of plants. Scientists discovered the sodium channel blocker ajmalin in the Indian snakeroot (Rauvolfia serpentina).

Quinidine , a substance from the China tree (Chinona pubescens), also belongs to class I antiarrhythmics . Digoxin , which belongs to the cardiac glycosides , is technologically obtained from a native plant: the well-known foxglove (digitalis) is a very old remedy. The deadly nightshade (Atropa belladonna) is a notorious fruit of Central Europe, whose alkaloid, atropine, is used in medicine in many ways, rarely also as an antiarrhythmic.

In addition to these substances of an organic-synthetic or biological nature, there are also inorganic preparations. Potassium and magnesium are mineral components of our daily diet and are used in high doses as antiarrhythmics. In established medicine, homeopathic preparations for cardiac arrhythmias are not considered an alternative to the “official” antiarrhythmics.

Risks & side effects

Overall, antiarrhythmics have a wide range of side effects because they are made up of a large number of individual substances. The beta blockers tend to be best tolerated.The most common are gastrointestinal problems, blurred vision and skin rashes . Psychological complications such as disorientation and depression are also among the undesirable effects. Paradoxically, side effects affecting the cardiovascular system appear. A change in medication or a dose reduction is then unavoidable. The active ingredients of plant origin in antiarrhythmics are by no means unproblematic.