Antiarrhythmic drugs basic concepts in pharmacology. Antiarrhythmic agent an overview sciencedirect topics. According to their effects on the rate of repolarization linked to potassium efflux, one subdivides them in. They include chinidin proper, as well as ajmaline, disopyramide, and prajmalium bitartrate. In the last decade no novel antiarrhythmics entered the pharmaceutical market, and none is presented in the list of top 200 drugs by sales for the 2010s. Class ic drugs, such as flecainide, moricizine, and propafenone. However, distinct differences within this class i action have necessitated subdivision of class i drugs into a, b, and c groups. Antiarrhythmic drugs are used to suppress abnormal heart rhythms by different mechanisms. May 20, 2009 market research data have suggested a severe underuse of the class ic agents. This is the reason some sources may classify some antiarrhythmic agents differently to other sources. According to their effects on the rate of repolarization linked to potassium efflux, one subdivides them in three subclasses ia, ib, ic.
It was estimated that the prevalence of side effects was 15 % in. Contents preface, v aknowledgments, viii part 1 basic principles chapter 1 mechanisms of cardiac tachyarrhythmias, 3 chapter 2 introduction to antiarrhythmic drugs, 36 part 2 clinical features of antiarrhythmic drugs chapter 3 class i antiarrhythmic drugs, 55 chapter 4 class ii antiarrhythmic drugs. Amiodarone has been reported to cause frequent and potentially serious toxicity. Class iii antiarrhythmics prolong the action potential and refractory period, acting primarily. On the other hand, virtually none of the class ii and iii drug, d,lsotalol, is. Lidocaine is an example of a class ib medication that is also used as a local anesthetic. Quinidine is an example of a class ia antidysrhythmic. Part of the handbook of experimental pharmacology book series hep, volume 89. The drugs preventing or treating cardiac arythmias are called antiarrhythmics. Patients who have received an intravenous antiarrhythmic should be monitored closely with serial ecgs. Phenytoin, an anticonvulsant and not a true local anesthetic, is sometimes classi. Antiarrhythmics pharmacology merck veterinary manual. A class ic drug was prescribed in 3,973 patients and a class iii drug in 6,909 patients. Class ic antiarrhythmics contain flecainide and propafenone.
Class ic drugs do not block i topotassium channels. They are new and potent drugs which markedly depress phase 0 of the action potential without affecting repolarization. Class iii antiarrhythmics encompass amiodarone, and the. Propafenone shows class ic and class ii antiarrhythmic effects. Antiarrhythmic drugsclinical use and clinical decision making. Antiarrhythmic definition of antiarrhythmic by the free. For patients with atrial fibrillation af, there are two main strategies to manage the irregular rhythm and its impact on symptoms. Class ic antiarrhythmic agents markedly depress the phase 0 repolarization decreasing vmax.
A mathematical model to understand the mechanisms of. Class ic antiarrhythmic drugs class ic drugs have slow kinetics. Many attempts have been made to classify antiarrhythmic agents. However, there are several limitations with this system and some newer antiarrhythmics can be classified into more than one class. Amiodarone as an iodinated benzofuran derivative is a potent antiarrhythmic drug that is being used for the treatment of a wide variety of cardiac arrhythmias. Class i antidysrhythmic medications slow conduction and prolong depolarization by decreasing sodium influx into cardiac cells. Potassiumchannel blockers, bind to and block the potassium channels which prolongs repolarization of the cell membrane. Clinical use of class ic antiarrhythmic drugs springerlink. Atrial fibrillation af is the most common arrhythmia, with incidence increasing with age and a ranging severity of symptoms. Antiarrhythmic drugs workbook and casebook for goodman. Antiarrhythmic agents, also known as cardiac dysrhythmia medications, are a group of. Class i antiarrhythmic drugs, also known as sodium channel blockers, are classified into three subgroups such as class ia quinidine, procainamide, disopyramide, acecainide, class ib lidocaine, mexiletine, tocainide, phenytoin, and class ic propafenone, flecainide, encainide, moricizine. Antiarrhythmic drug classes ii, iii, and iv are presented. Thus, an ecg obtained during normal rhythm at normal heart rates usually shows fastchannel tissue conduction slowing.
Ill cover the class i, class ii, class iii, class iv, class v, and then just give you some departing thoughts and then i will finish off with a couple of knowledge challenge questions, just to. Antiarrhythmic drug classification novel therapeutic. Our intention is not to offer a new pharmacology textbook or a research. Class ic drugs are more potent antiarrhythmics than either class ia or class ib drugs. Thus, some drugs belong to several classes and aads included in the. Class ic drugs may organize and slow atrial tachyarrhythmias enough to permit 1. Antiarrhythmic medications statpearls ncbi bookshelf. Sir, the pharmacology of antiarrhythmic drugs is very difficult to understand, specially that of class 1 antiarrhythmic drugs. This book is distributed under the terms of the creative commons attribution 4. In particular, it answers the most frequent questions that i get concerning the use of these agents in children, and is handy when writing prescriptions or inpatient orders. The svw classification categorizes antiarrhythmic drugs into four classes table 27. Flecainide, encainide, and propafenone belong to class ic antiarrhythmic drugs. In 1969, vaughan williams proposed a classification for antiarrhythmic drugs at an international meeting of cardiologists and electrophysiologists in elsinor, denmark vaughan williams 1970. The leeward foundation is a nonprofit group focused on feeding, clothing and heating needy families on the seacoast of massachusetts, new hampshire, and maine.
We introduce new classes based on additional targets. The primary action of class ii antiarrhythmics is to block beta adrenoceptors. Modernized classification of cardiac antiarrhythmic drugs. Class ib antiarrhythmics include substances related to lidocaine such as mexiletine, and also the teratogenic phenytoin only approved for epilepsy. Picmonic is research proven to increase your memory retention and test scores. However, this classification scheme typically does not aid in. The vaughanwilliams classification is a historic classification that groups antiarrhythmics into five main classes. Chapter 2 introduction to antiarrhythmic drugs, 36 part 2 clinical features of antiarrhythmic drugs chapter 3 class i antiarrhythmic drugs, 55 chapter 4 class ii antiarrhythmic drugs. We introduce new classes based on additional targets, including. This type of action potential is found in nonnodal, cardiomyocytes e. A mathematical model to understand the mechanisms of action.
Class ic drugs have the greatest effect on the early depolarization and have less of an effect on the refractory period of the ventricle. They decrease conductivity, but have a minimal effect on the action potential duration. Class ib drugs have less of an effect on phase 0, but shorten the action potential duration and refractory period of the purkinje fibers. Clicking on the drug class will link you to the page describing the pharmacology of that drug class and specific drugs. However, distinct differences within this class i action have necessitated subdivision of class. List of antiarrhythmic agents antiarrhythmics generics. Learn antiarrhythmic with free interactive flashcards. Pdf modernized classification of cardiac antiarrhythmic drugs. The book attempts to set out a framework for understanding antiarrhythmic drugs. There are three subgroups of sodium channel blockers. Antiarrhythmics class i antiarrhythmic agents flashcards. Class iv agents affect calcium channels and the av node.
Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances. Class ic flecainide is the prototype drug with group 1c actions. The most distinctive characteristic of the ic agents is that then bind slowly and dissociate slowly from the na channel campbell and vaughan williams 1983. One drug, quinidine, of group ia increases the action potential duration apd and effective refractory period erp and slows repolarization by blocking na channels. This antiarrhythmic drug guide was put together as a set of notes derived from elsewhere, with a focus on pediatric considerations. Please note that many of the drugs comprising the first five listed classes have considerable overlap in their pharmacologic properties. The real antiarrhythmic agents class i agents all class 1 a, b, and c agents have. Altered action potential of class1 antiarrhythmic drugs by mathematical model. Class iv antiarrhythmics involve the calcium channel blockers verapamil, gallopamil, and diltiazem. Class i antiarrhythmic drugs, also known as sodium channel blockers, are classified into three subgroups such as class ia quinidine, procainamide, disopyramide, acecainide, class ib lidocaine, mexiletine, tocainide, phenytoin, and class ic. The new scheme also aids classification of novel drugs under investigation. Preventing or alleviating irregularities in the force or rhythm of the heart. Class ii agents are antisympathetic nervous system agents.
Recent data suggest that these new class iii antiarrhythmic drugs are highly effective for. The value of class ic antiarrhythmic drugs for acute. Class 1 consists of sodium channel blockers, which in turn is divided into 3 subgroups namely 1a, 1b, and 1c. Class ic drugs do not block potassium channels directly. However, the electrophysiologic effects of some agents span more than one class, and some have ancillary properties unrelated to their antiarrhythmic effects. Novel therapeutic targets for antiarrhythmic drugs. Sodium channel blocking antiarrhythmic drugs are classified as usedependent in that they bind to open sodium channels. Sodiumchannel blockers comprise the class i antiarrhythmic compounds according to the vaughanwilliams classification scheme. Propafenone shows class ic and class ii antiarrhythmic. M ore f ries p lease moricizine, flecainide, propafenonoe term. Because some sodiumchannel blockers increase the erp class ia, while others decrease the erp class ib or have no effect on erp class ic, the vaughanwilliams classification recognizes these differences as subclasses of class i antiarrhythmic drugs. The five main classes in the vaughan williams classification of antiarrhythmic agents are. Sodium channel blockers antiarrhythmic drugs see online here the vaughanwilliams classi. These drugs bind to and block the fast sodium channels that are responsible for the rapid depolarization phase 0 of fastresponse cardiac action potentials.
Learn vocabulary, terms, and more with flashcards, games, and other study tools. Antiarrhythmic drug guide washington university in st. Modernized classification of cardiac antiarrhythmic. Their effectiveness is therefore dependent upon the frequency of channel opening.
Class i antiarrythmics inhibit the influx of sodium by the voltagegated channels, slow the speed of fast depolarization called phase 0, which leads to a decrease of the rate of conduction. In addition, both the marked increase of its plasma concentrations during exercise as well as its chemical structure are particular features of betaadrenoceptor antagonists 14,15 and herewith further support the fact that a single dose of 600 mg propafenone exerts both class ic and class ii antiarrhythmic effects according to the vaughan. Antiarrhythmic drugs have not been shown to enhance survival in nonlifethreatening ventricular arrhythmias and may increase mortality. Flecainide, propafenone should not be used for patients with any structural heart disease. A practical guide, second edition, you will have dependable information on how each drug works and when each one is indicated so you can give your patients the best possible treatment. Antiarrhythmic drugs workbook and casebook for goodman and.
Miscellaneous antiarrhythmic drugs constitute those whose mechanism of action cannot be attributed to a single class of effect. Antiarrhythmic drugs knowledge for medical students and. Several classes of antiarrhythmics, including beta blockers, calcium channel blockers, amiodarone, cardiac glycosides, and lidocaine, also have other medical uses, which are discussed in their respective learning cards. A class ic antiarrhythmic agent used to manage atrial fibrillation and paroxysmal supraventricular tachycardias psvt. Class ia antiarrhythmics belong to the chinidin type. Class ic drugs, such as flecainide, moricizine, and propafenone, dissociate very slowly from sodium channels and markedly slow conduction. Class ic antiarrhythmic drugs membrane stabilizing agents flecainide and propafenone. Likewise, the class ic drug, propafenone, is metabolized to 5hydroxypropafenone, which lacks the class ii. Drugs for arrhythmias merck manuals professional edition. Sodiumchannel blockers comprise the class i antiarrhythmic compounds. The new scheme also aids classification of novel drugs under. Choose from 500 different sets of antiarrhythmic flashcards on quizlet.
Antiarrhythmic agents, also known as cardiac dysrhythmia medications, are a group of pharmaceuticals that are used to suppress abnormal rhythms of the heart cardiac arrhythmias, such as atrial fibrillation, atrial flutter, ventricular tachycardia, and ventricular fibrillation. Antiarrhythmics are typically classified according to their predominant electrophysiologic effect on myocardial cells. Antiarrythmic drugs are classified according to their mode of action in four groups. These effects on erp are not directly related to sodium channel blockade, but instead are. The new scheme will additionally aid development of novel drugs under development and is. The majority of the antiarrhythmic agents, then and now, restrict the fast inward sodium current.
Class ii includes propranolol, acebutolol, and the shortacting betaadrenoreceptor antagonist esmolol. Class ic agents are indicated for lifethreatening ventricular tachycardiac or ventricular fibrillation, and for the treatment of refractory supraventricular. A class 1c antiarrhythmic agent used in the management of paroxysmal atrial fibrillationflutter and ventricular arrhythmias. Antiarrhythmic agents, also known as cardiac dysrhythmia medications, are a group of pharmaceuticals that are used to suppress abnormal rhythms of the heart cardiac arrhythmias, such as atrial fibrillation, atrial flutter, ventricular tachycardia, and ventricular fibrillation many attempts have been made to classify antiarrhythmic agents. Such aframework,itishoped,willnotonlyserveasaguidepostinmaking clinical decisions, but will also provide a basis for interpreting new information that comes to light on antiarrhythmic drugs and their place in the treatment of cardiac arrhythmias. The class i antiarrhythmic agents are sodium channel antagonists, with the class ic agents having a slow ionchannel dissociation and classes ia and ib having intermediate and fast dissociation kinetics, respectively.
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