Potassium Channel Blockers- & Its Pharmacology

Potassium channel blockers are classified as class III antiarrhythmic agents, use to modify or prolong the effects of potential and refractory period, that further go in order to combine with normal conduction velocity, as a result help to treat the cause of re-entrant arrhythmias. Although it didn’t affect the specific rate or duration cycle base on sodium channel, here a question arises in your minds why isn’t the sodium cycle affected? That is because, of its ion channel are supremely elegant and as per to modern periodic table that down the group every atom gets an increase in size so, same rule apply their potassium has bigger Pauling radius compare to sodium.

potassium channel blockers pharmacology

Pharmacology of cardiac potassium channels:

Basically, the cardiac potassium channels are cardiomyocyte membrane made from the polymeric structure of membrane on the electrochemical gradient and as well create an ease to determine the complete duration of the resting membrane potential and the cardiac action potential morphology. Most of the potassium channels having the transient outward potassium current of I(to1) in human heart, the ultra-rapidly activating delayed rectifier current I(Kur), the rapidly and slowly activating delayed rectifier currents I(Kr) and I(Ks), the inward rectifier potassium current I(K1), and ligand-gated potassium channels, including adenosine-5′-triphosphate (ATP)-sensitive potassium current (I(KATP)) and acetylcholine-activated current (I(KACh)) respectively. Common changes of potassium proteins that help to regulate the continuous flow of potassium ions, through the whole cell channel boost to the morphologies and effect a bit in the time period of cardiac action potentials from sinus node, atrial to ventricular myocytes, and various ventricular layers from endocardium and mid-myocardium to epicardium. In addition, they exhibit translational responses to endogenous regulators or pharmacological agents. However, potassium channels are mostly known for its secretion that helps in developing anti-arrhythmic drugs, which can effect inhibit cardiac arrhythmias. Furthermore, an atrial-specific potassium channel current (I(Kur) and I(KACh)) are the cause for the developing atrial-selective anti-atrial fibrillation drugs.

Potassium Channel Blockers list:

Potassium channel blockers examples and uses:


This class III antiarrhythmic agent was first discovered in WHO lab, used in treating cardiac dysrhythmias, including both ventricular and atrial. However, this agent has some common side effects.

Medical uses:

As we know Amiodarone has been utilizing to operate both supraventricular arrhythmias and ventricular arrhythmias

Cardiac arrest:

The affection of ventricular fibrillation (VF) and ventricular tachycardia, resulting in Cardiac arrest. In case if you get sudden cardiac arrest (SCA). A man having SCA should be treated with a defibrillator immediately. This gadget sends an electric stun to the heart. The electric stun helps heart to regain its rhythm back.

Atrial fibrillation:

It’s also caused due to blockage of a heart channel, resulting in a disturbance in the heart beat if it cannot be treated in right time you will die. Medicines for atrial fibrillation, include prescriptions to control heart rate and lessen the danger of stroke, and techniques, for example, cardioversion to re-establish typical heart rhythm.


It’s a class III agent, was first discovered by a team named Tikosyn. It is generally available in the form of capsules.

Medical uses:

Dofetilide is used to maintain the flow of sinus rhythm.


In this method, we take oral quinacrine at doses of 37.5 mg/kg/D and 75 mg/kg/D, at 4 consecutive weeks (keep in mind must take 4 consecutive weeks otherwise may it not help you). Plasma and tissue (brain, liver, spleen) samples were taken over 8 weeks: 4 weeks of treatment, while 4 weeks after treatment get completed.


Basically, metabolic syndrome causes due to changes in diet and lifestyle to administering cholesterol-lowering and diabetes medications. However, you have to careful with your health as well maintain your blood pressure.


It is a drug, that was initially discovered on 1968s and tested upon the 1980s.

Medical uses:

It is mainly prescribed by the doctors to those who are the patients of cardiac arrhythmias

Beta-blocker action:

Beta blockers, well-known by the name of beta-adrenergic blocking agents. However, by using this agent we can able to treat a variety of causes like cardiac arrhythmia, high blood pressure, glaucoma, and migraines.

Type III antiarrhythmic action:

This agent is used when a person causing a heart attack. Doctors, immediately take this to the patient and result in, it reduces the abnormal contraction of ventricles. However, in this way it helps heart to regain its rhythm back.


It is basically an antiarrhythmic agent, found by the group called “Tikosyn”.

Medical uses:

It helps in balancing the rate of both atrial fibrillation and Atrial flutter.


It is also used to balance the cause of Pharmacokinetics, method its explain above with the same dose but the medicine is Ibutilide instead Dofetilide.

Side effects:

As these all drugs have some side effects, so make sure you will take it all the medicines according to the doctor prescription.

Torsades de pointes:

Torsades de pointes are basically a form of polymorphic VT in patients and having a long QT time period. It is caused, due to rapid, irregular QRS complexes, that seem to be twisting around the ECG outermost baseline. This arrhythmia initially takes growth in ventricular fibrillation. Furthermore, it can cause hemodynamic compromise and often death.

Risk factor:

Congenital long QT syndromes and long QT interval, these are the commonly considered risk of Torsades de pointes.


Congenital long QT syndrome: Beta-adrenergic class III antagonists are initially being treated as a first-line long-term therapy in congenital long-QT syndrome. However, many doctors are using Propranolol in this process because the better agent and highly effective with lesser side effects. Beta-blockers are used in many cases since bradycardia secreted by these drugs that can encourage the production of Torsades. They ought to likewise be kept away from in those innate cases in which bradycardia is a noticeable element. Continuously pacing advantages patients who stay symptomatic in spite of accepting the maximally endured dose of beta-blockers and can be utilized as a part of an expansion to beta-blockers.

Acquired long QT syndrome: Treatment in many cases is typically not required on the grounds that the QT interim comes back to the ordinary state if the inclining component has been returning to its original state back. Pacemaker implantation is compelling in cases that are connected with heart piece or bradycardia.

Hi, This is Hamza Khan from Peshawar, Pakistan. I am a 2nd prof MBBS Student at Bannu Medical College and a hobby Blogger. The Purpose of this site is to share my knowledge and Guide new Medical Students.

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