Antiarrhythmic Drugs Pharmacology: Classification, Pharmacology, Indications and, Examples
Arrhythmias (also called dysrhythmias) involve changes in the automaticity and conductivity of the heart cells. Class I antiarrhythmics This class blocks sodium channels in the cell membrane during an action potential. The subgroup under this class is based on their mechanism of blocking sodium channels. These classes are local anesthetics and membrane-stabilizing agents because of their ability to bind more quickly to sodium channels. Therapeutic Action Class, I antiarrhythmics stabilize the cell membrane by depressing phase 0 of the action potential. They bind to sodium channels and change the duration of the action potential of the cells. Class Ia drugs depress phase 0 and prolong the duration of the action potential. Class Ib drugs somewhat depress phase 0 and shorten the duration of the action potential. Class Ic drugs markedly depress phase 0 and extremely slow conduction but has little effect on the duration of action potential Class II antiarrhythmics This class interferes with action potential by blocking beta receptors in the heart and kidneys. This, in turn, blocks phase 4 of action potential. Class II antiarrhythmics are beta-adrenergic blockers Class III antiarrhythmics This class prolongs and slows down the outward movement of potassium during phase 3 of action potential. These drugs act directly on the heart muscles to prolong repolarization and refractory period. All of these drugs are proarrhythmic and have the possibility of inducing arrhythmias Class IV antiarrhythmics Include two calcium-channel blockers, namely: diltiazem and verapamil. This class blocks the movement of calcium towards the cell membrane. Join this our membership section to get access to perks: / @medcrine SUBSCRIBE, LIKE and SHARE Check our website for more medical lecture notes at https://medcrine.com Follow us on twitter @medcrine Facebook at www.fb.me/medcrine Pinterest at pinterest.com/medcrine Telegram at t.me/medcrine email us on [email protected]
