Konorev Anti-arrhythmic Drugs Flashcards
Phase 0 fast action potential?
Voltage gated Na channels open and Na enters
Phase 1 fast action potential?
- K exits cell and fast Na channels close
- Repolarization
Phase 2 fast action potential?
- Plateau phase from K exiting cells offset by Ca entering cells
Phase 3 fast action potential?
- Ca channels close and K begins to exit rapidly resulting in repolarization
Phase 4 fast action potential?
- Resting membrane potential gradually restored by Na/K ATPase and Na ca exchanger
What are the Class 1A Na channel blocking drugs?
- Quinidine
- Procainamide
- Disopyramide
What are the class 1B Na channel blocking drugs?
- Lidocaine
- Mexiletine
What are the Na channel blocking class 1C drugs?
- Flecainide
- Propafenone
what are the class 2 Antiarrhythmic Beta blockers?
- Propranolol
- Esmolol
What are the class 3 antiarrhythmic potassium channel blocking drugs?
- Amiodarone
- Sotalol
- Dofetilide
- Ibutilide
Class 4 antiarrhythmic Cardioactive Ca channel blocker drugs?
- Verapamil
- Dilitazem
Miscellaneous antiarrhythmic agents?
Adenosine
MOA of class 1A Na channel blockers?
- Block Na channels
- Reduces slope of phases 0
- Prolongs QRS interval of ECG
- Also blocks K channels
- Prolongs action potential duration
- Prolongs QT interval
What are the clinical uses of Procainamide and what class does this drug fall into?
- Class 1A Na channel blocker
- Not frequently used, but is used for sustained ventricular tachycardias and arrhythmia assoc. with MI
AE’s of Procainamide?
- QT prolongation and induction of torsade de pointes
- Lupus erythematosus syndrome with arthritis, pleuritis, pulmonary disease, hepatitis and fever
- Hypotension
Quinidine use and class and AE?
- Rarely used bc of AE’s
- QT prolongation and induction of Torsade de pointes and syncope
- GI issues
- Tinnitus
- Thrombocytopenia
- Class 1A Na channel blocker
Disopyramide class and unique feature?
- Class 1A Na channel blocker
- also strong antimuscarinic effect on heart
How do class 1B Na channel blockers work?
- Slow or completely block conduction in damaged tissue
- Dissociate from channel with fast kinetics
- Bind to inactivated sodium channels
- NO QT prolongation bc these don’t block K channels
Describe Lidocaine, what class, MOA, use and AE?
- Extensive first pass metabolism (only IV use)
- Termination of vent tachy in setting of MI
- Least toxic of all class 1 drugs
- may cause hypotension in HF patients
- Paresthesia, tremor, slurred speech
Mexiletine?
- Similar to lidocaine, but can be given orally
Class 1C drug MOA?
- Bind to open Na channels and block them
- Dont dissociate completely from channels and this results in prolongation of QRS interval
What class is Flecainide what is use and AE?
- Class 1 C Na channel blocker
- Supraventricular arrhythmia & Refractory ventricular arrhythmia
- May cause severe exacerbation of ventricular arrhythmias in patients with:
- preexisting vent tachy arrhythmias
- previous MI
- Ventricular ectopic rhythm
How is Propafenone different from Flecainide? What is the class?
- Class 1 C Na channel
- Has better blocking activity
How do class 2 antiarrhythmic Beta blockers work?
- Block sympathetic effect on cardiac pacemaker cells by increasing cAMP
- Effects funny current If
- Increases L type Ca channel current
How do beta blockers impact SA and AV node?
- Decrease slope of If and Ca channels
- SA node:
- Decreases HR increases RR interval
- AV:
- Decrease AV conductance increase PR interval
Propranolol uses and class?
- Arrhythmias associated with stress, thyroid storm, and MI
- A fib and flutter
- Paroxysmal supraventricular arrhythmias
- Class 2 antiarrhythmic Beta blocker
Esmolol use? Class?
- Class 2 antiarrhythmic Beta Blocker
- Prolongs PR interval
- Similar to Propranolol
- SVT arrhythmia or thyroid storm
- Arrhythmia assoc with MI
- acts as adjunct drug in general anesthesia to control arrhythmia
Potassium channel blockers MOA
- Voltage gated K channels are responsible for repolarization and this class blocks them
Class 3 drug effects on ecg?
Prolong QT interval
Amiodarone effects?
- Most widely used class 3 drug
- also blocks K, Na and Ca channels
- Prolongs QT interval
- Causes bradycardia and slows AV conduction
Amiodarone clinical use?
- Recurrent ventricular tachycardia
- A fib
Amiodarone AE’s?
- Fatal pulmonary fibrosis
- Thyroid disturbances
- Low incidence of torsade de pointes even though it prolongs QT interval
Sotalol unique feature?
- Class 2 (beta blocker) and class 3 (prolongs APD) agent
- used for life threatening ventricular arrhythmia and maintenance of sinus rhythm in a fib
Dofetilide and Ibutilide MOA?
Blocks rapid component of delayed rectifier potassium current
How do class 4 Ca channel blocker drugs work? (impact on phases and threshold?)
- Block L type Ca channels
- decrease the slope of phase 0
- Increase L type ca threshold potential
Verapamil and Diltiazem uses? Class?
- Used for paroxysmal SVT and rate control in A. fib and flutter
- Class 4 Ca channel blocker
How does Adenosine work?
- slows conductivity via AV node by activating A1 Adenosine receptor a Gi GPCR
- Enhances K current and inhibits Ca and funny channels causing hyperpolarization
- Inhibits AV conduction and increases AV nodal refractory period
Between Sotalol and Esmolol which one will prolong QT?
- Sotalol the K channel will prolong QT
- Both will prolong PR interval
47 yo man diagnosed with exertional angina started tx with sublingual nitroglycerin as needed and oral isosorbide mononitrate. Which of the following is a potential detrimental effect of nitrates that may offset drug’s benefits?
a. decrease vent wall tension
b. increased heart rate
c. increased capacitance of systemic veins
D. increased ventricular end diastolic volume
b. increased heart rate
