Drug specificity is an important concept in pharmacology that refers to the range of actions a drug can produce. Understanding drug specificity is crucial for healthcare professionals, researchers, and patients alike, as it helps to predict the drug’s effects and potential side effects. Here, we explore the factors that govern drug specificity and provide examples … Read more
Adenosine Adenosine is antiarrhythmic agent that is widely used for the investigation and management of both narrow complex and, less often, broad complex tachycardias. It produces a transient block in the atrioventricular node. This effect is mediated by interaction with A1 receptors (reducing cyclic adenosine monophosphate) present on myocytes, thereby activating potassium channels, which increases K+ efflux, … Read more
Verapamil and diltiazem are non‑dihydropyridine calcium channel blockers classified as Class IV antiarrhythmics, primarily used to slow atrioventricular (AV) nodal conduction and control ventricular rate in supraventricular tachyarrhythmias such as atrial fibrillation and atrial flutter when left ventricular function is preserved.Both agents inhibit L‑type calcium channels in nodal tissue, reduce SA/AV nodal automaticity and conduction, and … Read more
Class III antiarrhythmics predominantly prolong cardiac repolarization via potassium channel blockade, with amiodarone as the prototypical agent and additional options including dofetilide, sotalol, ibutilide, and dronedarone chosen based on structural heart disease, heart failure status, and proarrhythmic risk.These drugs extend action potential duration and the QT interval to prevent reentry, while differing substantially in extracardiac toxicity, need … Read more
Introduction Among the diverse categories of drugs used to manage cardiac arrhythmias, beta-adrenoceptor-blocking drugs (beta blockers)—classified as Class 2 antiarrhythmics under the Vaughan Williams scheme—play a pivotal role in controlling aberrant cardiac rhythms, improving survival in many patient populations, and reducing complications of ischemic heart disease. Centrally, they inhibit the effects of endogenous catecholamines (especially norepinephrine … Read more
Propafenone is a Class 1C antiarrhythmic that produces potent, use‑dependent blockade of fast cardiac Na+ channels with slow unbinding kinetics, resulting in marked conduction slowing and QRS widening, and it also exhibits weak β‑blocking properties that influence rate and bronchial tone in some patients. The following chapter summarizes pharmacology, clinical use, cautions, and monitoring of … Read more
Flecainide is a Class 1C antiarrhythmic agent widely used for rhythm control in atrial and ventricular arrhythmias, particularly in patients without significant structural heart disease. The following summarizes its pharmacology, clinical uses, cautions, and monitoring, referencing key pharmacology textbooks and clinical reviews in Vancouver style. Overview Flecainide is a potent blocker of cardiac sodium (Na+) channels, … Read more
Mexiletine is an oral Class IB antiarrhythmic and sodium channel blocker structurally related to lidocaine, used primarily for ventricular arrhythmias and selected channelopathies such as LQT3 where late sodium current inhibition is desired.Its key antiarrhythmic actions are fast-on/fast-off block of fast Na+ channels with preference for inactivated channels in ischemic tissue, leading to rate‑dependent suppression … Read more
If you trained in a time when every crash cart seemed to include “lido,” you remember lidocaine as the go-to antidote for ugly ventricular ectopy. Today, it has a more selective role—but when it is the right drug, it can be lifesaving. Lidocaine (also known as lignocaine) is a prototypical Class 1B antiarrhythmic with rapid … Read more
Introduction Disopyramide is a Class 1a antiarrhythmic agent, primarily used in the treatment of ventricular tachycardia. It functions as a sodium channel blocker, inhibiting conduction by depressing the increase in sodium permeability of cardiac myocytes during the initial phase of the cardiac action potential. This reduces the inward sodium current, leading to an increased threshold … Read more