Press "Enter" to skip to content

How do potassium channel blockers work?

A class of drugs that act by inhibition of potassium efflux through cell membranes. Blockade of potassium channels prolongs the duration of ACTION POTENTIALS. They are used as ANTI-ARRHYTHMIA AGENTS and VASODILATOR AGENTS.

What happens if Na+ channels are blocked?

Complete block of sodium channels would be lethal. However, these drugs selectively block sodium channels in depolarized and/or rapidly firing cells, such as axons carrying high-intensity pain information and rapidly firing nerve and cardiac muscle cells that drive epileptic seizures or cardiac arrhythmias.

What happens when sodium channels open?

Role in action potential Voltage-gated sodium channels play an important role in action potentials. If enough channels open when there is a change in the cell’s membrane potential, a small but significant number of Na+ ions will move into the cell down their electrochemical gradient, further depolarizing the cell.

How do fast sodium channel blockers affect the heart?

These channels are normally found along the conduction pathway, especially near the sinoatrial (SA) node and the atrioventricular (AV) node. By blocking these channels, these drugs reduce the heart rate and the speed of conduction in the heart.

Is diazepam a sodium channel blocker?

It is concluded that diazepam causes a faster block and unblock of Na+ channels than the other compounds. The effective concentrations of diazepam are, however, higher than the free plasma levels reached therapeutically, e.g., during the treatment of epileptic seizures.

Which of the following is considered a Class I sodium channel blocker?

Class I: Fast sodium (Na) channel blockers Ia -Quinidine, procainamide, disopyramide (depress phase 0, prolonging repolarization) Ib -Lidocaine, phenytoin, mexiletine (depress phase 0 selectively in abnormal/ischemic tissue, shorten repolarization)

What is a class 3 antiarrhythmic?

A class III antiarrhythmic drug used for the maintenance of normal sinus rhythm and cardioversion in cases of atrial fibrillation and atrial flutter.

How are antiarrhythmic drugs classified?

This classification system is comprised of four categories. Class I agents block sodium channels. Class II agents are Beta blockers. Class III agents prolong the cardiac action potential.

Which drug is a Class III Antidysrhythmic?

Antidysrhythmic drugs The drugs that have been incriminated include disopyramide, encainide, flecainide, mexiletine, moracizine, procainamide, and quinidine [65–71]. The class III drug d-sotalol has also been associated with an increased risk of mortality in such patients [72].

Are beta blockers antiarrhythmics?

Beta blockers are class antiarrhythmics and are commonly used to treat supraventricular tachycardias.

What is the most toxic antiarrhythmic agent?

In terms of its toxicity, amiodarone remains the most feared of the antiarrhythmic agents.

What are beta blockers examples?

Examples of beta blockers

  • Acebutolol (Sectral)
  • Atenolol (Tenormin)
  • Bisoprolol (Zebeta)
  • Metoprolol (Lopressor, Toprol XL)
  • Nadolol (Corgard)
  • Nebivolol (Bystolic)
  • Propranolol (Inderal, InnoPran XL)

Do beta blockers stop arrhythmias?

The most common arrhythmia is atrial fibrillation (AF), which is commonly treated with beta blockers such as atenolol, bisoprolol and metoprolol. Beta blockers may stop the arrhythmia occurring but, more often, are useful for slowing down the heart rate during the arrhythmia without actually terminating it.