Class II antiarrhythmics

Class II Antiarrhythmic Agents The p-Adrenoceptor Blocking Agents... 

Propranolol. Propranolol (Table 1), a Class II antiarrhythmic agent, is usefiil in the management of hypertrophic subaortic stenosis, especially for the treatment of exertional or other stress-induced angina by improving blood flow. The dmg can increase exercise tolerance in patients suffering from angina. Propranolol has been shown to have cardioprotective action in post-MI patients (37—39,98,99,108). 

Metoprolol. Metoprolol tartrate (Table 1), also a Class II antiarrhythmic agent, is a HpophiHc, cardioselective P -adrenoceptor blocking agent... 

Other P"Adrenoceptor Blocking Agents. Carteolol hydrochloride (Table 1) is also a Class II antiarrhythmic agent. In three separate studies in patients having angina pectoris, carteolol was considered effective as evidenced by a reduction in the frequency and severity of anginal episodes, reduction in the amount of nitroglycerin consumed, improvement of ECG parameters, or an increase in the duration of trea dmill exercise (42). 

Class II antiarrhythmic drugs are (3-adrenoceptor antagonists such as propranolol, metoprolol or atenolol. (3-adrenoceptor antagonists slow sinus rate and atrioventricular conduction and exert negative inotropic effects. 

Class II antiarrhythmic drugs include beta (( -adrenergic blocking drugs, such as acebutolol (Sectral), esmolol (Brevibloc), and propranolol (Inderal). These drugp also decrease myocardial response to epinephrine and norepinephrine (adrenergic neurohormones) because of their ability to block stimulation of p receptors of the... 

Class II antiarrhythmic drugs competitively inhibit /3-adrenoceptors and inhibit catecholamine-induced stimulation of cardiac 15-receptors. In addition, some members of the group (e.g., propranolol and acebutolol) cause electrophysiological alterations in Purkinje fibers that resemble those produced by class I antiarrhythmic drugs. The latter actions have been called membrane-stabilizing effects. 

The p adrenoceptor antagonists (beta blockers) are class II antiarrhythmic agents. They prolong phase 4 of the cardiac action potential (pacemaker potential), slowing the heart rate. There are three subtypes of P adrenoceptors Pi, P2 and P3. Stimulation of Pi adrenoceptors in the heart increases the force and rate of cardiac contraction, as well as increasing automaticity of the pacemaker sites and conduction through the AV node. The P2... 

Actions of class II antiarrhythmics (beta blockers) involve antagonism of SANS mediated increases in j cAMP, especially at SA and AV nodal cells to slow phase 0 and 4 of the action potential. ... 

Beloc-Zok H 93/26 succinate Metoprolol succinate Seloken ZOC Selozok Spesicor Dos Toprol XL. A p-adrenergic blocker. Lacks inherent sympathomimetic activity. Antianginal class II antiarrhythmic anti-hypertensive. Apothecon Astra Chem. Ltd. Astra Sweden Ciba-Geigy Corp. Lemmon Co. 

What is the general mechanism of action of class II antiarrhythmics ... 

I Class II antiarrhythmic drugs are beta-blockers that decrease SA and AV nodal activity, decrease the I phase 4 slope, and prevent p, adrenoceptor activation, thereby circumventing the normal increase in I cAMR Propranolol is nonselective acebutolol and esmolol are selective. Their antiarrhythmic use is I discussed. 

Guamieri T, Datorre SD, Bondke H, Brinker J, Myers S, Levine JH. Increased pacing threshold after an automatic defibrillator shock in dogs effect of class I and class II antiarrhythmic drugs. Pacing Clin Electrophysiol 1988 11 1324-1330. 

RED FLAG Use class II antiarrhythmics cautiously in patients with pulmonary disease. 

---