Pharmacology: Katzung antiarrythmic drugs Flashcards
Procainamide, Disopyridamide, and quinidine belong to which group of drugs?
They are group 1A anti-arrythmics
What is the MOA for Procainamide, Disopyridamide, and quinidine?
They block either inward sodium or inward potassium channels. This slows the conduction velocity, slows pacemaker activity and prolongs action potential and refractory period.
What are the clinical applications for Procainamide, Disopyridamide, and quinidine?
(1) Atrial and ventricular arrythmias particularly after myocardial infarction.
What are the adverse effects associated with Procainamide, Disopyridamide, and quinidine?
(1) increased arrythmias
(2) Hypotension
(3) Lupus like syndrome
What makes disopyramide different than the other group 1A antiarrythmics?
disopyramide has a longer duration of action and has extra toxicities that include antimuscarinic effects and heart failure.
What differnetiates quinidine from the other group 1A anti-arrythmics?
Quinidine has an extra toxicity called cinchonism which includes
(1) tinnitus
(2) headache
(3) GI disturbance
To which group of drugs do Lidocaine and Mexiletine belong?
They are Group 1B anti-arrythmics?
What is the MOA for Lidocaine and Mexiletine?
Highly selective and state dependent block of inward Na channels. Minimal effect in normal tissue.
What are the clinical applications for Lidocaine and Mexiletine?
(1) Ventricular arrythmias post myocardial infarction
(2) digoxin-induced arrythmias.
What are the adverse effects associated with Lidocaine and Mexiletine?
CNS sedation or exitation
What differentiates mexiletine from lidocaine?
Mexiletine has oral activity and a longer duration of action.
To what group of drugs does Flecainide belong to?
Flecainide is a group 1C anti-arrythmic
What is the MOA for Flecainide?
it causes a selective and state dependent block of inward Na channels. This leads to slowed conduction velocity and slowed pacemaker activity.
What are the clinical applications for flecainide?
refractory arrhythmias.
What adverse effects are associated with Flecainide?
(1) increased arrhythmias
(2) CNS excitation
To what class of arrhythmics do propranolol and Esmolol belong to?
The are Group 2 arrhythmics. (also they are beta blockers)
What is the MOA for propranolol and Esmolol?
They block beta receptors thus slowing pacemaker activity?
What are the clinical applications for propranolol and Esmolol?
(1) post MI as prophylaxis against death
(2) ventricular fibrillation
(3) Thyrotoxicosis
What are the adverse effects associated with propranolol and Esmolol?
(1) Bronchospasm
(2) Cardiac depression
(3) AV block
(4) Hypotension
To what class of anti arrhythmics do Amiodarone, Sotalol, Ibutilide and dofetilide belong to?
They are group 3 anti arrhythmics.
What is the MOA of amiodarone?
Strong inward K channel blocker that produces marked prolongation of the action potential and refractory period. Group 1 activity slows conduction velocity. Group 2 and 4 activity confer additional anti-arrhythmic activity.
What are the clinical applications for amiodarone?
(1) refractory arrhythmias
2) used off label in many arrhythmias. (broad spectrum of action
What are the adverse effects associated with amiodarone?
(1) thyroid abnormalities
(2) deposits in the skin and cornea
(3) pulmonary fibrosis
(4) optic neuritis
What is the MOA for Sotalol?
It blocks inward K channels and beta adrenoreceptors
What are the clinical applications for sotalol?
(1) ventricular arrhythmias
(2) atrial fibrillation
What are the adverse effects associated with sotalol?
(1) dose dependent torsade de pointes
(2) Cardiac depression
What is the MOA of Ibutilide?
Selective inward K blocker the prolongs the action potential and the QT interval
What is the clinical application for ibutilide?
atrial fibrillation
What are the adverse effects associated with ibutilide?
Torsade de pointes
What is the MOA of Dofetilide?
Selective inward K blocker the prolongs the action potential and the QT interval
What are the clinical applications for dofetilide?
treatment and prophylaxis of atrial fibrillation
What adverse effects are associated with defetilide?
Torsade de pointes
What class of anti-arrhythmics are verpamil and diltiazem?
They are Group 4 anti-arrhythmics
What is the MOA for verpamil and diltiazem?
They cause state and use dependent inward Ca channel blockage that slows conduction in the AV node, slows pacemaker activity, and prolongs the PR interval.
What are the clinical applications for verpamil?
AV nodal arrhythmias especially in prophylaxis
What are the clinical applications for Diltiazem?
rate and control in atrial fibrillation
What are the adverse effects associated with verpamil and diltiazem?
(1) cardiac depression
(2) constipation
(3) hypotension
Which drugs are considered miscellaneous anti-arrhythmics?
adenosine
Postassium ion
Magnesium ion
What is the anti-arrhythmic MOA for adenosine?
It increases diastolic inward K current of the AV node. this causes hyperpolarization and conduction block. It also reduces inward Ca.
What are the clinical applications for adenosine?
acute nodal tachycardias
What is the anti-arrhythmic MOA of Potassium Ion?
(1) increase in all K currents
(2) decreased automaticity
(3) decreased digitalis toxicity
What are the anti-arrhythmic clinical applications of postassium ion?
(1) Digitalis toxicity
(2) other arrhythmias if K is low.
What are the adverse effects associated with potassium ion?
(1) arrhythmogenesis (hyper and hypo kalemia)
2) cardiac arrest (severe hyperkalemia
What is the anti-arrhythmic MOA for magnesium Ion?
Poorly understood possible increase in Na/K ATPase activity.
What are the clinical applications for Magnesium Ion?
(1) Digitalis arrhythmias
(2) Other arrhythmias if Mg is low
What are the adverse effects associated with magnesium ion?
(1) muscle weakness
(2) respiratory paralysis
(severe hypermagnesemia)
What are the general characteristics of group 1A anti-arrhythmics?
They are sodium channel blockers that prolong the action potential duration
What are the general characteristics of group 1B anti-arrhythmics?
They are sodium channel blockers that shorten the action potential
What are the general characteristics of group 1C anti-arrhythmics?
They are sodium channel blocker that have no effect on Action potential duration.
