How does sotalol work?
Sotalol is a so-called class III antiarrhythmic drug (= potassium channel blocker). It prolongs the electrical excitation (action potential) in the atria and ventricles of the heart by inhibiting the outflow of potassium ions from the heart muscle cells.
Sotalol thereby prolongs the so-called QT interval. This interval in the ECG represents the total duration of ventricular excitation
Excitation of the heart
Our heart must contract (contract) at regular intervals to pump blood into the circulatory system – that is, to supply the body and its organs with blood.
Each contraction of the heart muscle is triggered by an electrical excitation of the heart muscle cells. This excitation starts in the so-called pacemaker cells of the sinus node:
Further transmission of excitation occurs via the so-called His bundle, the ventricular bundles and the Purkinje fibers in the heart chambers (ventricles). Through this complex system, the heart is secured against stopping several times.
About 60 to 80 excitations per minute emanate from the sinus node.
What are the side effects?
Sotalol (like other antiarrhythmic drugs) can also trigger potentially dangerous cardiac arrhythmias (such as torsade de pointes). Therefore, treating physicians assess the benefit-risk profile individually for each patient before prescribing sotalol.
For more rare side effects, see the package insert of your sotalol medication. Contact your doctor or pharmacist if you suspect any unwanted side effects.
How dangerous is sotalol?
The risk of drug-induced cardiac arrhythmias (e.g., torsade de pointes) was underestimated for a long time. In the meantime, however, antiarrhythmic drugs are subject to numerous contraindications and restrictions on use because of this risk.
If therapy with antiarrhythmic drugs is necessary, the treating physicians monitor the patients closely.
When is sotalol used?
How to take sotalol
Sotalol is available as tablets containing 80 or 160 milligrams of active ingredient. Take the tablets unchewed before meals with plenty of liquid (e.g., a glass of water).
Treatment is usually started in adults with 80 milligrams of sotalol twice daily. If this dose does not work sufficiently, it can be increased after two to three days at the earliest – to 80 milligrams three times daily to 160 milligrams twice daily.
During dose adjustment, patients’ cardiac function is carefully monitored. Regular check-ups are also necessary during the course of treatment.
When should sotalol not be taken?
Sotalol should generally not be used in the following cases:
- If you are hypersensitive or allergic to the active ingredient or any of the other ingredients of the drug.
- after an acute heart attack
- shock
- in the context of anesthesia, which favors a reduced cardiac output
- dysfunction of the heart’s “pacemaker” (sinus node syndrome or sick sinus syndrome)
- medium- and high-grade disturbance of the transmission of excitation between the atria and the ventricles (AV block of the second or third degree)
- cardiac arrhythmia with slowed heartbeat (bradycardia)
- pre-existing QT time prolongation
- renal failure (because sotalol is excreted through the kidneys)
- low blood pressure (hypotension)
- late-stage peripheral circulatory disorders (e.g. in arms, legs)
- respiratory diseases with narrowing of the airways (obstructive respiratory diseases) such as COPD and bronchial asthma
- metabolically induced low blood pH (metabolic acidosis)
- untreated pheochromocytoma (rare tumor of the adrenal cortex)
- children and adolescents under 18 years of age (lack of experience)
These drug interactions may occur with sotalol
Simultaneous use of other agents that also block beta receptors promotes drops in blood pressure and a slowing of the heartbeat (bradycardia).
Sotalol, like other antiarrhythmic drugs and narcotics, can reduce the pumping force of the heart. This so-called negative inotropic effect may increase when these agents are used in combination.
- other antiarrhythmic drugs (such as flecainide, ajmaline, amiodarone, dronedarone)
- antidepressants (SSRIs, tri- and tetracyclics such as fluoxetine, (es-)citalopram, sertraline, amitriptyline, imipramine, maprotiline)
- Antibiotics (such as ciprofloxacin, moxfloxacin, erythromacin, clarithromycin, and azithromycin)
- Antimalarials (such as chloroquine and halofantrine)
- Agents against allergies (antihistamines) such as famotidine, promethazine and diphenhydramine
- Anti-nausea agents (such as domperidone and ondansetron)
- Donepezil (agent for dementia)
- Methadone (substitute for opioid dependence)
- Hydroxyzine (anti-anxiety agent)
- Fluconazole (antifungal agent)
The effect of sotalol on heart rate (decrease) and conduction (slowing) may increase if any of the following agents are used at the same time:
- Clonidine, reserpine, or alpha-methyldopa (agents for hypertension and other conditions)
- guanfacine (agent for ADHD)
- cardiac glycosides (agents for heart failure)
Conversely, blood pressure can also drop sharply when certain medications are taken at the same time. These medications include:
- Tricyclic antidepressants (such as amitriptyline)
- Barbiturates (drugs with sedative, narcotic and sleep-inducing effects, e.g. anti-epileptic drugs such as phenobarbital)
- Phenothiazines (drugs for psychoses)
- Anesthetics (narcotics)
- Blood pressure medications
- Dehydrating agents (diuretics)
- vasodilators (such as glycerol trinitrate)
Magnesium deficiency increases the risk of arrhythmias with sotalol. Proton pump inhibitors (heartburn medications) such as omeprazole, lanzoprazole, pantoprazole, and rabeprazole are suspected of promoting magnesium deficiency.
With potassium-excreting diuretics such as furosemide and hydrochlorothiazide, there is a risk of potassium deficiency-induced cardiac arrhythmias occurring during sotalol therapy.
Sotalol enhances the effect of certain muscle relaxant drugs – neuromuscular blockers derived from tubocurarine. Such drugs are primarily used in intensive care medicine.
The simultaneous use of sotalol and diabetes medications (insulin, oral antidiabetics) can trigger hypoglycemia and mask its signs. The danger is particularly present during simultaneous physical exertion.
Sotalol during pregnancy and lactation
To date, there is insufficient experience with the use of sotalol during pregnancy and lactation. The decision on the use of sotalol is made by physicians together with their patients.
Because sotalol crosses the placenta well, it is also suitable for the treatment of arrhythmias with accelerated heartbeat (tachycardia) in the unborn child.
