Disopyramide

At Disopyramide it is an antiarrhythmic. It is therefore used in particular for drug therapy for cardiac arrhythmias. The active ingredient disopyramide is similar to the drugs procainamide and quinidine. In most cases, the drug is given by the oral route. Most of the active substance is excreted from the human organism via the kidneys.

What is disopyramide?

The active ingredient disopyramide is counted among the first class antiarrhythmics. It is administered either orally or in the form of intravenous injections. The bioavailability of the drug disopyramide is more than 80 percent.

In the blood, the active ingredient binds to around 40 percent of the proteins present in the plasma. Basically, the drug's plasma half-life is around seven hours. The drug is then metabolized by the hepatic system (the center of which is the liver). Thereafter, the active substance is mainly excreted from the organism via the kidneys, i.e. via the kidneys.

The drug disopyramide was patented in 1962. In practical use, the active ingredient disopyramide is present as a racemate.

Pharmacological effect

The drug disopyramide works primarily as a so-called sodium channel antagonist. Thus, the active ingredient leads to fewer sodium ions flowing into the myocardium. As a result, the excitability of the heart is reduced. This is how the drug disopyramide unfolds its negative bathmotropic effect. Finally, the substance also leads to the refractory period being extended. As a result, there is a negative chronotropy.

First and foremost, the active ingredient disopyramide blocks those sodium channels that are located on the cell membranes inside the heart muscle. These are the cells that are responsible for regulating the heart rhythm. In this way, the active ingredient lengthens the action potential.

Basically, the drug disopyramide is characterized by anti-parasympathetic effects and is thus similar to the substance atropine. In addition, the drug shows no effectiveness in relation to special adrenoceptors in the sympathetic nervous system. In addition, the active ingredient reduces the refractory period of the heart chambers and their atria.

The drug disopyramide significantly reduces the performance of the left ventricle. In addition, it causes the arterial blood vessels to expand. As a result, blood pressure drops. The active ingredient is therefore problematic for people whose pumping function is impaired. In such cases, treatment with the drug disopyramide should be avoided.

Medical application & use

Disopyramide is suitable for the treatment of numerous diseases and health complaints. Indications are primarily certain functional disorders of the heart. These include, for example, ventricular tachycardias and extrasystoles as well as ventricular fibrillation. Therapy with the drug disopyramide is also possible for supraventricular tachycardias, such as atrial flutter or fibrillation.

It is possible to combine disopyramide with other active ingredients from the group of antiarrhythmic drugs if a single drug does not have a sufficient effect. In addition, disopyramide is able to prevent a recurrence of atrial fibrillation following cardioversion.

Before using the active ingredient disopyramide for the first time, it is necessary to check the ventricular frequency. In this way, a so-called 1: 1 transition can be avoided. Disopyramide is also suitable for the treatment of neurogenic syncope and hypertrophic cardiomyopathy.

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Risks & side effects

Various undesirable symptoms and side effects are possible while taking the drug disopyramide. However, these do not occur in every patient and differ in their frequency. For example, constipation (constipation) and urinary retention as well as dry mouth are possible. In some cases, disorders of accommodation and narrow-angle glaucoma also occur. In addition, the performance of the left ventricle may be affected. The risk of this increases if the patient already suffers from a weak heart.

Treatment with disopyramide also increases the QT time in some cases. Torsade de pointes tachycardias are also possible. Some patients experience hypotension (drop in blood pressure) or circulatory problems when taking the drug disopyramide.

Other potential side effects are agranulocytosis and glaucoma. Acute heart failure, which has been observed in some people, is also a dangerous complication.

In addition, there are some contraindications for the drug disopyramide. If, for example, there is decompensated cardiac insufficiency or bradycardia, the drug disopyramide should not be administered. If the affected patient has coronary artery disease, the drug disopyramide is not the drug of choice. Because in this case the risk of death is increased. If the active ingredient disopyramide is to be used anyway, an examination using a cardiac catheter is necessary before the first use.

Even in the case of hypersensitivity to the drug or heart failure, the drug should not be administered. Further contraindications exist in the sick sinus syndrome, a disturbed electrolyte balance and liver or kidney weakness.

In addition, interactions with other substances are possible, which is why simultaneous use is not recommended. Tricyclic antidepressants, erythromycin and neuroleptics lead to a prolongation of the half-life of disopyramide. As a result, they increase the effectiveness of the drug.

Basically, all undesirable side effects and complaints caused by the drug disopyramide give rise to consultation of a doctor. The doctor may then prescribe an alternative preparation.