Arrythmic Drugs Flashcards
Quinidine
Type 1A Na channel blocker
Used in restoring rhythm in Atrial flutter/fib
has antimuscarinic effect and may enhance AV conductance
can cause hypotension -> tachycardia.
can cause prolonged QT -> torsades
can cause tinnitus, Gi side effects, headache, dizziness, hepatitis, fever, and thrombocytopenia.
Procainamide
Type 1A Na channel blocker
Used in sustained ventricular tachycardias and arrhymias associated with MI
Directly depresses AV and SA nodes
has antimuscurinic activity
Has come class 3 activity (block K channels)
can cause QT prolongation -> can cause torsades
can cause lupus erythematous syndrome with arthritis, pleuritis pulmonary disease, hepatitis, and fever, as well as nausea, diarrhea, and agranulocytosis
Disopyramide
Class 1A Na channel blocker
used in recurrent ventricular arrhythmias
Can cause prolonged QT
Has Potent ANTIMUSCARINIC EFFECTS which have atropine like symptoms. (urinary retention, dry mouth, blurred vision, ect.
Lidocaine
Class 1B Na channel blocker
Block Sodium channels selectively (no K channels)
Blocks conduction in depolarized tissue making them electrically silent (used after MI)
Used in mono and polymorphic ventricular tachycardias.
VERY EFFICIENT WITH ARRHYTHMIA’S after MI
Only given IV
Can cause Paresthesias, tremor, slurred speech, and convulsions.
Mexiletine
Class 1B Na channel blocker
Orally active drug
Used in Ventricular arrhtymias
used to relieve chronic pain especially because of diabetic neuropathy and nerve injury
can cause tremor, blurred vision, nausea, lethargy
Flecainide
Class 1C Na channel blocker
blocks Na and K channels
No antimuscarinic effects
used for SVT (and AVNRY and AVRT)
Used in life threatening ventricular arrhythmias like V tach.
Don’t use in patients with preexisting ventricular tachyarrhtymias, previous MI, and Ectopic rhythms
Propafenone
Class 1C Na channel blocker
Possesses weak Beta blocking activity.
used to prevent AF and SVT
also used in Sustained ventricular arrhythmias
Causes a metallic taste, exacerbation of ventricular arrhythmias, Constipation,
Dont combine with CYP2D6 and CYP3A4 inhibitors as there is risk of proarrhtyhmia is increased.
Esmolol
Class 2 channel blockers (beta blockers)
used in supra ventricular arrhythmia
Used in arrhythmias associated with thyrotoxicosis.
Has a rapid onset and offset. (10 min) given IV, rapid on and off.
Propranolol
Class 2 channel blockers (beta blockers)
Used for arrhythmias associated with stress
used in Re-entrant arrhythmias like ACNRT and AVRT.
Used in A fib and flutter.
Amiodarone
Class 3 potassium channel-blocking drugs
prolongs QT and action potential duration.
has some Ca channel blocking activities
causes bradycardia and slows AV conduction.
Used in treatment of ventricular arrhythmias and A. fib.
Metabolized by CYP 3A4
Its effects last for 1 to 3 months. can even be in system up to 1 year after.
Can cause AV block
can cause pulmonary fibrosis, hepatitis, photo dermatitis, Optical neuritis, and hypo/hyperthyroidism.
Dronedarone
Class 3 potassium channel-blocking drugs
Will block multiple K channels and prolong repolarization and refractory period
Will block Na current as well as L type Ca channels which leads to decreased nodal conduction that will cause bradycardia and proposed AV refractory period and P-R interval.
Can cause worsening Heart Failure.
Sotalol
Class 3 potassium channel-blocking drugs
Non-selective Beta blocker that also block K channels
prolongs Action Potential duration
can be used for life threatening ventricular arrhythmias and Maintenance of sinus rhythm in patents with A. Fib.
Dofetilide
Class 3 potassium channel-blocking drugs
Specifically blocks rapid component of the delayed rectifier potassium current -> its effect is more pronounced at lower heart rates.
Eliminated by kidneys
narrow therapeutic window
Used to convert A. fib to sinus rhythm and maintain a sinus rhythm after cardiovert.
can cause prolonged QT and increased ventricular arrhythmias.
Ibutilide
Class 3 potassium channel-blocking drugs
Verapamil
Cardioactive calcium channel blockers
Blocks both activated and inactivated L type channels
Will decrease phase 0 slope and depolerization.
Slows SA node -> bradycardia
Prolongs AV node action potential duration & refractory period.
Diltiazem
Cardioactive calcium channel blockers
Blocks both activated and inactivated L type channels
Used in prevention of paroxysmal SVT
Used in Rate control of AF and A. flutter.
Can cause negative isotropy, AV block, SA arrest, Bradyarrhythmias and hypotension.
Class 1A channel blockers
Block Na channels. Binds to K channels too. Binds to open channels more preferentially Blocks K channels Prolongs QRS and QT intervals Prolongs action potential duration
Class 1B Drugs
Block Na channels
Bind to Inactivated Na channels.
Prefentrally bind to depolerized cells
Disassociate with Na channels fast -> no effect on normal tissues
May shorten action potential
Dont block K channels (only bind to Na)
Dont prolong action potentials or QT duration on ECG.
Class 1C blockers
Blocks the Na channel
Slow impulse conduction
Dissociates from channel with slow kinetics
Block Certain K channels
Dont prolong action potential duration and QT interval duration of the EKG
**Prolong QRS
Class 2 drugs
Beta blockers
Slow action potential
SA -> decrease HR -> RR interval
AV -> decrease AV conductance -> Increase PR interval
Decrease Ca overload -> prevents delayed after polarization of the ventricular myocardium
Class 3 drugs
Block K channels
Prolong action potential duration and Qt interval on ECG
Atrial depolarization is rate dependent with the most armed effects at slow HR.
*prelongs refractory period
Class 4 drugs
Block Ca channels
Block both activated and inactivated L-type channels
Active in slow response cells decrease the slope of Phase 0
Slows SA node depolerization
Slows AV conduction
May suppress delayed afterdepolerizations (DAD)
Adenosine
Activated potassium current and inhibits Ca and funny currents
Cuased hyper polarization and supression of action potentials in pacemaker cells.
Inhibits AV conductance and increases refractory period
Conversion to sinus rhythm from SVT.
Side effects SOB Bronchoconstriction (A1 and A2b receptors "adenosine receptors") Chest burning Av block hypotension
torsade de pointes
A type of arrhythmia that is caused by prolonged QT syndrome
caused by early afterdepolarizations that are often associated with impaired function of K channels
Digoxin induced arrythmias
Causes tachyarythmies and ectopic rhythms
caused by delayed afterpolerizations.
occurs during phase 4 from increased cytosolic Ca from drug inhibiting Na/K ATPase.
