ANTI-ARRHYTHMIC DRUGS Flashcards
The ultimate goal of antiarrhythmic drug therapy is to
Restore normal sinus rhythm and conduction
Prevent more serious and possibly lethal arrhythmias from occurring.
Antiarrhythmic drugs are used to
decrease conduction velocity
change the duration of the effective refractory period (ERP)
suppress abnormal automaticity
classify antiarrhythmic drugs according to Vaughan William
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Class 1A Drugs
Quinidine
Procainamide
Class IA Drugs Uses
Supraventricular and ventricular arrhythmias
Class IA Drugs Toxicity
quinidine-
AV block
Torsade’s de pointes arrhythmia
↑digoxin concentration
Ventricular tachycardia
procainamide-
Asystole or ventricular arrhythmia
Hypersensitivity : fever, agranulocytosis
Class IB Drugs
Lidocaine, Mexiletine
Class IC Drugs
Propafenone, Flecaimide
Class II ANTIARRHYTHMIC DRUGS uses
(β-adrenergic blockers)
Treatment of increased sympathetic activity-induced arrhythmias such as stress- and exercise-induced arrhythmias
Class III ANTIARRHYTHMIC DRUGS
Amiodarone, Sotalol
Class III ANTIARRHYTHMIC DRUGS Uses
Ventricular arrhythmias, especially ventricular fibrillation or tachycardia
Supra-ventricular tachycardia
Class IV ANTIARRHYTHMIC DRUGS examples
: verapamil & diltiazem
used because they act on the heart only and not on blood vessels.
Dihydropyridine family are not used because they only act on blood vessels
DRUGS TO TREAT HEART FALIURE classification
inotropic drugs
diuretics
aldosterone antagonist
beta blockers
vasodilators
Inotropic drugs
examples
Cardiac glycosides:
Digoxin, digitoxin
Sympathomimetic amines:
Dopamine , dobutamine
Phosphodiesterase inhibitors:
Amrinone , milrinone
Vasodilators examples
Arteriolar: hydralazine , minoxidil,
Venodilators: nitrates
Arteriolar and venodilators: ACE inhibitors, ARB
diuretics examples
Loop diuretics: furosemide, torsemide
Thiazide diuretics: hydrochlorthiazide
K+ Sparing diuretics:
Spironolactone
Amiloride
Beta Blockers
(cardioselective)
Metoprolol, atenolol
Digoxin –Mechanism of action
Induces an increase in intracellular sodium that will drive an influx of calcium in the heart and cause an increase in contractility
Also inhibits the AV Node
Uses of digoxin
Congestive heart failure
Cardiac arrhythmias
Adverse effects of digoxin
GIT: Nausea & vomiting (first to appear)
CNS: Restlessness, Disorientation
Endocrine: Gynaecomastia
Cardiac
Bradycardia (first cardiac toxic sign)
arrhythmia
Treatment of toxicity
Stop digitalis
Digoxin antibodies
Oral or parenteral potassium supplements
For ventricular arrhythmias- Lidocaine IV
For supraventricular arrhythmia-Propranolol IV or orally
For AV block and bradycardia- Atropine IM
DOPAMINE
An endogenous catecholamine
Induces intrarenal vasodilatation, inhibition of renal tubular sodium reabsorption
Direct stimulation of peripheral dopaminergic receptors DA1 and DA2
In higher doses may affect the Beta-1 and alpha receptors promoting tachycardia and PVR
Hence, the preference of the synthetic amine, dobutamine, which is more beta-1 specific
Dobutamine
Synthetic catecholamine
Stimulates beta1, beta 2 and alpha-1 receptors
Has no effect on dopamine and alpha -2 receptors
Dobutamine is preferred when there is a need to improve low cardiac output.
DRUGS TO TREAT ANGINA PECTORIS
ORGANIC NITRATES: Glyceryl trinitrate (Nitroglycerin), Isosorbide dinitrate, etc
•BETA BLOCKERS: Propranolol, Atenolol, Metroprolol, Carvedilol, etc
• CALCIUM ANTAGONIST: Nifedipine, Diltiazem, Verapamil
