Sotalol is a pharmacological agent that belongs to the beta-blocker category. The drug is primarily used for the treatment of cardiac arrhythmias. Sotalol is a special beta-blocker that does not have a phenol ether structure. In its structure, the substance also resembles beta-isoprenaline.
What is sotalol?
The drug sotalol is among those beta-blockers that are nonselective. This is because the drug does not bind specifically to beta-1 adrenergic receptors. Unlike the drugs oxprenolol and acebutolol, it has no so-called sympatomimetic activity. Basically, the substance sotalol occurs in the form of racemate. Thus, potassium channels are blocked. In addition, the drug sotalol has an L-form, which is why it is effective as a beta-blocker. Also, the drug has a so-called enantiomeric unit, which influences the efficacy of the substance.
Pharmacologic action
Basically, the drug sotalol causes potassium channels to close. For this reason, the drug sotalol belongs to the third class of antiarrhythmic drugs. The drug prolongs the refractory period as well as the action potential. It also blocks specific beta-1 receptors inside the heart. As a result, the conduction velocity and contractility of the heart muscle are reduced. Furthermore, the frequency of the heart as well as the excitability of the heart are decreased. In addition, inhibition of the sympathetic nervous system occurs as well as rein secretion. Thus, in the long term, the patient’s blood pressure decreases. All antiarrhythmic drugs of the third class are characterized by the fact that they block potassium channels. In particular, the active ingredient sotalol slows down the potassium current that is responsible for repolarization. Special electrophysiological measurements have shown that the action potential of isolated heart muscle cells is prolonged. As a result, the refractory period of the cells of the heart muscle is also prolonged. Inhibition of potassium channels is primarily responsible for this. The bioavailability of the active substance sotalol is almost one hundred percent. However, no binding to plasma proteins is detectable. In principle, the control options for the drug are rather limited, since the plasma half-life is approximately 15 hours. The active substance is primarily excreted renally. For this reason, it is imperative to adjust the dose in patients with existing renal impairment. Due to its enormously long plasma half-life, the drug sotalol is one of the beta-blockers with the longest duration of action.
Medical use and application
The drug sotalol is primarily used in the treatment of various cardiac arrhythmias. Thus, the drug is a so-called antiarrhythmic agent. Possible areas of application for the active ingredient include coronary heart disease, cardiac arrhythmias and arterial hypertension. This is because the drug is also capable of lowering blood pressure.
Risks and side effects
Sotalol is characterized by a number of potential adverse side effects that must be weighed before administering the drug. In particular, the blockade of potassium channels results in the drug triggering specific side effects in some cases. This also distinguishes sotalol from numerous other beta-blockers. The main characteristic is that the substance sotalol itself can lead to cardiac arrhythmias under certain circumstances. Torsade de pointes tachycardia is a particularly dangerous complication. It sometimes triggers ventricular fibrillation, which in some cases results in immediate cardiac death. Such side effects are particularly apparent in the case of kidney weakness, high-dose intake and electrolyte disorders. The so-called long-QT syndrome also sometimes promotes similar side effects. Medical research studies have shown that women are three times as likely as men to be affected by torsade de pointes tachycardia while taking sotalol. For this reason, administration of the drug sotalol should be discouraged if QT time is prolonged. The drug sotalol is also contraindicated in some other medical conditions. These include sinus bradycardia and asthma attacks. This is because so-called bronchoconstriction is possible in these cases, since the drug sotalol activates the beta-2 receptors.Sotalol should also be avoided in patients with AV conduction disorders. Finally, there is a risk of hypoglycemia, particularly in patients with diabetes, due to inhibition of glycogenolysis as a result of the blocked beta-2 receptors. Other contraindications include pregnancy and breastfeeding. This is because the active ingredient sotalol passes into breast milk. In general, the undesirable side effects and symptoms of the drug sotalol occur with varying frequency. In addition, they differ depending on the individual case and person in their expression, their severity and the combination of various side effects. Some patients treated with the drug sotalol suffer from no undesirable side effects at all. Other individuals are affected by mild to severe symptoms. It is therefore particularly important to thoroughly weigh up the individual risk factors of the respective patient, such as existing kidney weakness, before taking the drug sotalol for the first time. In the course of this, the attending physician discusses the patient’s personal medical history in order to minimize the risk of serious complications while taking the drug. In addition, it is the patient’s responsibility to contact a physician immediately if any symptoms arise. It may be necessary to discontinue sotalol and find an alternative therapeutic option.
