anti-arrhythmia drugs Flashcards
class I B example
lidocaine iv
class I B action, indication
Fast binding offset kinetics
No change in phase 0 in normal tissue (no tonic block)
APD slightly decreased (normal tissue)
increase threshold (Na+) decrease phase 0 conduction in fast beating or ischaemic tissue,
ECG; None in normal, in fast beating or ischaemic increase QRS
For : Ventricular tachycardia (esp. during ischaemia)
Not used in atrial arrhythmias or AV junctional arrhythmias
class IB
CNS effects: dizziness, drowsiness
GI; Abdominal upset
class I C example
flecainide, oral or iv
class I C action
very slow binding offset kinetics (>10 s) Substantially decrease phase 0 (Na+) in normal decrease automaticity (increase threshold) increase APD (K+) and increase refractory period, esp in rapidly depolarizing atrial tissue. Effects on ECG increase PR, increaseQRS, increaseQT
class I C use
Wide spectrum Used for supraventricular arrhythmias (fibrillation and flutter)
Premature ventricular contractions (caused problems)
Wolff-Parkinson-White syndrome
class I C
Pro-arrhythmia and sudden death especially with chronic use (CAST study) and in structural heart disease
increase ventricular response to supraventricular arrhythmias (‘flecainide flutter’)
CNS and gastrointestinal effects like other local anesthetics
class II example
bisoprolol,oral metoprolol iv, oral
class II action
increase APD and refractory period in AV node to
slow AV conduction velocity
decrease phase 4 depolarization (catecholaminedependent)
Effects on ECG inc PR, dec HR
class II use
sinus and catecholamine dependent tachycardia
in atrial flutter or atrial fibrillation
Ectopic beats bisoprolol
Metoprolol for VT
class II
bronchospasm
hypotension
don’t use in partial AV block or acute heart failure (are used in stable heart failure)
class III example
amiodarone oral, iv
sotalol oral
amiodarone action
Effects on ECG inc PR, inc QRS, incQT, decHR increase refractory period and inc APD (K+) dec phase 0 and conduction (Na+) inc threshold dec phase 4 (β block and Ca++ block) dec speed of AV conduction
amiodarone use
wide spectrum, most arrhythmias
amiodarone
Pulmonary fibrosis
Hepatic injury Increase LDL cholesterol
Thyroid disease
Photosensitivity optic neuritis (transient blindness)
^ amiodarone
reduce the dose of digoxin and monitor warfarin more closely
sotalol action
inc APD and refractory period in atrial and ventricular tissue
Slow phase 4 (β blocker)
Slow AV conduction
ECG effects inc QT, dec HR
sotalol use
Wide spectrum: supraventricular and ventricular tachycardia
sotalol
Proarrhythmia,
fatigue, insomnia
class IV example
verapamil: oral or i.v. diltiazem: oral
class IV action
slow conduction through AV (Ca++)
inc refractory period in AV node
inc slope of phase 4 in SA to slow HR
Effects on ECG inc PR, inc/dec HR
class IV use
control ventricles during supraventricular tachycardia
convert supraventricular tachycardia (re-entry around AV)
class IV
Caution when partial AV block is present. Can get asystoleif β blocker is on board Caution when hypotension, decreased cardiac output or sick sinus
Some gastrointestinal problems (constipation)
class V example
adenosine iv,
Digoxin
Atropine
Ivabradine oral
adenosine action
natural nucleoside that binds A1 receptors and blocks adenylyl
cyclase thus reducing cAMP which in turn activates K+ currents in AV and SA node causing hyperpolarization → dec HR
leads to dec Ca++ currents - inc refractory period in AV node
Slows AV conduction
adenosine use
convert re-entrant supraventricular arrhythmias diagnosis of coronary artery disease (scans)
ivabradine oral action
blocks If ion current highly expressed in sinus node
Cardiac effects
slows the sinus node but does not affect blood pressure
ivabradine
flashing lights
teratogenicity not known (avoid in pregnancy)
ivabradine uses
reduce inappropriate sinus tachycardia
reduce heart rate in heart failure and angina (NICE guidance)
(avoiding blood pressure drops)
digoxin action
enhances vagal activity (inc K+ currents, dec Ca++ currents, inc refractory period
slows AV conduction and slows HR
digoxin use
treatment to reduce ventricular rates in atrial fibrillation and flutter,
atropine action
selective muscarinic antagonist
block vagal activity to
speed AV conduction and increase HR
atropine uses
treat vagal bradycardia
