Sotalol hydrochloride is used in equine practice primarily as an antiarrhythmic. It’s primary indication is in the management of atrial fibrillation. Although the drug will not convert horses to normal sinus rhythm it is useful in the post-conversion period to reduce the risk of reoccurrence. It is typically administered as a tablet twice daily.
How does it work?
Sotalol has several modes of action. It is primarily a Class III anti-arrhythmic drug, which means it works on potassium (K+) channels. Specifically it inhibits rapid outward potassium current through its actions on hERG (Kv11.1) channels in the heart. This results in an increase in the action potential (AP) recovery time and refractory period (RP), as well as decreasing the tendency for re-entry.
The drug is also in the Class II anti-arrhythmic category, which means it is a non-selective Beta blocker, acting on both beta1 and beta 2 adrenergic receptors. This causes a reduction in ‘automaticity’ of the sinoatrial node, atrioventricular node, and from ectopic foci in the atria or ventricles. These effects have a positive impact on controlling the heart rate.
What is it used for?
In humans it is used for a variety of conduction issues, including supraventricular arrhythmias, such as atrial fibrillation and atrial tachycardia. It is also in humans with ventricular tachycardia.
Decloedt and others in 2018 reported that sotalol decreased the heart rate and increased both the QT interval and atrial fibrillation cycle length (AFCL) in horses with atrial fibrillation when given twice daily for 3 days. This suggested that sotalol may have a positive effect on controlling very high rates in atrial fibrillation horses at exercise, although long-term safety and efficacy data are lacking.
In horses it is primarily used as a pre-medication for atrial fibrillation conversion, and as a therapy to reduce the reoccurrence of atrial fibrillation in the 28 days after successful conversion. According to Vernemmen and colleagues in 2022 pre-medication resulted in the need for a lower amount of energy to convert AF to a sinus rhythm using transvenous electrical cardioversion. Interestingly, they indicated by way of multivariable analyses, that post-conversion treatment with sotalol increased the risk of reoccurrence. Importantly, they noted that the horses that received sotalol were considered to be at a greater risk of reoccurrence, and therefore the recommendation to use remains.
Dosing
Dosing information is intended for use by registered veterinarians or veterinary nurses. Equiimed assumes no responsibility for the information detailed below. Equiimed shall not be liable for any damages resulting from reliance on any information provided below, or by reason of any misstatement or typographical errors. Ultimately veterinarians should consult information provided by the manufacturer prior to use.
Tags: Pharmacology; Cardiology