Drugs to Treat Dysrhythmias Flashcards
Effects of Proarrhythmic drugs (4)
Increased automaticity
Conduction block or slowing
Decreased/ increased ERPs
Heterogeneity of ERP
Effects of antiarrhythmic drugs (5)
Decreased automaticity
Restore conduction (depressed conduction/ reverse reentry)
Decreased conduction
Decreased/ increased ERPs (reverse/ block reentry)
Homogeneity of ERPs
Class I antiarrhythmic drug
Na channel block
Class II antiarrhythmic drug
Beta-receptor block
Class III antiarrhythmic
Prolong APD
Class IV antiarrhythmic
Ca channel block
Class IA
Moderate dissociation rate
Class IB
Rapid dissociation
Class IC
Slow dissociation
State dependent ion channel block
Class I antiarrhythmic drug Binding to open/ inactivated channel Association during systole Dissociation during diastole Block related to depolarization (HR, ischemia, APD) Block related to dissociation rate
Class IA drugs (3)
Procainamide
Quinidine, Disopyramide
Procainamide
Class IA drug
Class IA: function
Direct effect: decrease automaticiy and conduction velocity, increase APD and ERP
Anticholinergic effects
Class IA: effects on AV node
Direct effect= decrease AV conduction
Anticholinergic= increase AV conduction
Net= variable AV conduction
Class IA: contra
Prolonged QT syndrome causes Torsades de pointes
Class IA: indication
Life-threatening ventricular arrythmia
Procainamide: kinetics
Well absorbed orally (or IV)
RE and HM
Procainamide active metabolite
NAPA
Procainamide: ADR
+ANA (Lupus-like syndrome)
Agranulocytosis/ Leuopenia
Proarrhythmic effects
Conduction block, decreased myocardial contractility, hypotension, GI
Procainamide: contra
Prolonged QT
Hypokalemia
SLE
Class IB
Lidocaine
Mexiletine
Lidocaine
Class IB drug
Mexiletine
Class IB drug
Class IB: general characteristics
Minimal effects on normal myocardium
Class IA action in diseased myocardium
Lidocaine: indication
Life threatening V arrhythmias
Digoxin-induced arrhythmias
Lidocaine: pharmacokinetics
HM (first pass elimination)
Decrease dose in liver disease and CHF
IV only
Lidocaine: ADR
CNS (disorientation to seizures)
Hypotension
Decrease cardiac contractile
Lidocaine: Contra
Hypersensitivity to Amides
Severse hepatic dysfunction
History of lidocaie-induced seizures
Mexiletine: ADR
GI
Tremors
CNS
Thrombocytopenia *
Class IC
Flecainide
Propafenone
Clas IC: general
Markedly slow conduction
ADP, ERP +/-
Decrease automaticity
Flecainide: indication
Life threatening V. arrhythmias in absence of organic heart disease
Disabling supraventricular arrhythmias in absence of organic heart disease
Flecainide: ADR
Increase Post MI mortality Conduction block CHF (by decreased contractility) Proarrhythmic AV block
Propafenone: general
Similar to Flecainide
Weak Beta blockade (class II)
Proarrhythmic
Negative inotropic effect *
Class II: MoA
Inhibit sympathetic input Decrease automaticity Decrease conduction velocity Increase Refractoriness Prominent effects on SA/ AV nodes Decrease contractility
Class II: indication
Supraventricular arrhythmia A flutter and fib Symptomatic PVC Post MI CHF
Class II: ADR
Bronchoconstriction CHF AV block Cold extremities Increase insulin induced hypoglycemia Block Increase in HR (hypoglycemia)
Class II (3)
Propranolol (nonspecific Beta blocker)
Metoprolol (cardioselective beta-blocker)
Esmolol (cardioselective, short, control V rate in A fib/ flutter, control sinus tachycardia)
Class III: general
Homogeneous prolongation of APD (proarrhythmic)
Class III: indication
Refractory, life-threatening ventricular arrhythmia
Class III drugs
Amilodarone
Dronedarone
Ibutilide/ Dofetilide
Amiodarone:general
Highly efficacious
DOC acute suppression of V arrhythmia
refractory life threatening V tach
Sustained V tach
Amiodarone: kinetics
Highly lipophilic
Very long half life (month)
Amiodarone
Class III
Amilodarone: ADR
Pulmonary fibrosis Hyper/hypothyroidism Hepatotoxicity AV block, Bradycardia Proarrhythmic Corneal microdeposite, photosensitivity, blue/gray nose/ cheeks
Dronedarone
Class III
Dronedarone: indication
Prevent A flutter/ fib
Dronedarone: kinetics
24 hr half life
Dronedarone: ADR
Increase mortality in CHF
Liver injury/ failure
(Monitor liver function 6 mos)
Ibutilide/ Dofetilide
Class III
Ibutilide/ Dofetilide: inidication
Prolong ADP/ERP
Terminate A flutter/ fib
Ibutilide/ Dofetilide: ADR
Proarrhythmic (Torsades de pointes)
Sotolol
Class III + nonselective Beta blockade
Sotolol: indication
Life-threatening ventricular arrhythmia
Prevent recurrence of symptomatic A flutter/ fib
Sotolol: ADR
Prolongs QT (Torsades de pointes)
Verapamil
Class IV
Class IV
Verapamil
Verapamil: MoA
In SA/ AV nodes
Decrease firing rate of SA node (decrease HR)
Decreased conduction velocity in AV node
Increase APD and ERP (increase AV refractoriness)
In Atrial/ ventricular muscle
Decrease contractility
Vasodilation + decrease CO= Decrease BP
Class IV: indication
Supraventriular arrhythmias
PSVT with AV notal reentry
A flutter/ fib
Verapamil: ADR
Hypotension
CHF
AV block
Constipation
Verapamil: drug interaction
Concurrent Beta blocker
Digoxin
Antiarrythmic drugs
HM interaction (Cimetidine)
Adenosine
Decrease AV doncution
short acting
Rapid uptake/ adenosine deaminase
Rapid bolus dosing
Adenosine: indication
Acute termination of PSVT
Adenosine: ADR
Asthma and COPD
Vagomimetics
Decrease AV conduction
Terminate PSVT
Valsalva
Carotid sinus massage
Drug that controls V rate in A/ fib and flutter
Digoxin
Drugs that increase conduction, AS node rate
Treat bradyarrhythmias
Atropine
Isoproterenol
Know the graphs for Class I-IV
Refer to the lecture ppt 1/14/2016