What is the difference between class Ia and Ib antiarrhythmics?

What is the difference between class Ia and Ib antiarrhythmics?

Class I drugs are subdivided based on the kinetics of the sodium channel effects: Class Ib drugs have fast kinetics. Class Ic drugs have slow kinetics. Class Ia drugs have intermediate kinetics.

How sodium channel blockers work in arrhythmia?

A class of drugs that act by inhibition of sodium influx through cell membranes. Blockade of sodium channels slows the rate and amplitude of initial rapid depolarization, reduces cell excitability, and reduces conduction velocity.

How do fast sodium channel blockers affect the heart?

Therefore, blocking sodium channels reduces the velocity of action potential transmission within the heart (reduced conduction velocity; negative dromotropy). This can serve as an important mechanism for suppressing tachycardias that are caused by abnormal conduction (e.g., re-entry mechanisms).

How do you learn antiarrhythmic drugs?

The mnemonic to remember the different classes of antiarrhythmic medications is “Some Block Potassium Channels”. “Some” = Sodium channel blockers = Class I antiarrhythmics. “Block” = Beta blockers = Class II antiarrhythmics. “Potassium” = Potassium channel blockers = Class III antiarrhythmics.

What is a class 3 antiarrhythmic?

Class III antiarrhythmic drugs act by blocking repolarising currents and thereby prolong the effective refractory period of the myocardium. This is believed to facilitate termination of re-entry tachyarrhythmias. This class of drugs is developed for treatment of both supraventricular and ventricular arrhythmias.

What is a Class 1 antiarrhythmics?

Class I antiarrhythmic drugs are. Sodium channel blockers (membrane-stabilizing drugs), which block fast sodium channels, slowing conduction in fast-channel tissues (working atrial and ventricular myocytes, His-Purkinje system)

How does blocking potassium channels treat Dysrhythmias?

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.

How do Class 1b antiarrhythmics shorten action potential?

Class I antiarrhythmic drugs can decrease the automaticity of an ectopic pacemaker by either 1) blocking the Ih pacemaker current (thereby decreasing the slope of diastolic depolarization), 2) shifting the threshold for action potential generation to a more positive potential (increasing threshold) by blocking …

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.

How do you remember antihypertensive drugs?

ABCD = Main Antihypertensive Classes As mentioned above, antihypertensives are medications that treat high blood pressure or hypertension. There are several different classes of antihypertensives, and they can be remembered using the acronym “ABCD”.

How are the different classes of antidysrhythmic drugs work?

Antidysrhythmic drugs work by correcting abnormal cardiac function. There are four classes of antidysrhytmics which each have a different mechanism of action. Class I drugs work on sodium channels, and are subdivided in a, b, and c classes.

Why are antiarrhythmic drugs not good for You?

These drugs are classified based on their electrophysiological effect on the . Antiarrhythmic drugs do not improve the survival of patients with non-life-threatening . They are associated with severe adverse effects, primarily due to their proarrhythmic effects on the .

How does Class 1 antiarrhythmic suppress abnormal automaticity?

Class 1 antiarrhythmic agents can suppress abnormal automaticity by decreasing the slope of phase 4, which is generated by pacemaker currents. The mechanism for this is not understood and is unrelated to blocking fast sodium channels.

Which is antiarrhythmic drugs increase the effective refractory period?

Antiarrhythmic Drugs. This effectively culminates in increasing the effective refractory period. Class 4 consists of calcium channel blockers and it works by blocking the L-type calcium channels. These channels are normally found along the conduction pathway, especially near the SA node and AV node.