Antiarrhythic Therapy

Question 1

Anti-arrhythmic agents

Answer 1

1a) quinidine, procainamide, disopyramide
1b) mexilitene, didocaine
1c) flecainide, propafenone
III) sotalol, dofetilide, dronedarone, ibutilide (channel blockers)
- amiodarone, ranolazine

Question 2

Ia - Quinidine

Answer 2

• stereo isomer of quinine, derived from cinchona tree
• blocks fast inward Na+ channel: use dependent=more block w/ faster heart rate, prolongs action potential duration & QT interval (not good)

Question 3

Ia - Quinidine: reason for decreased usage

Answer 3

• used for Afib & ventricle tachycardia till 1990s

- caused diarrhea, thrombocytopenia, hepatitis, TORSADES DE POINTES due to QT prolongation

Question 4

Ia - Quinidine: new uses

Answer 4

• brugada syndrome & early repolarization syndrome

Question 5

Ia - Quinidine: metabolism

Answer 5

• live metabolism: cytochrome p450

Question 6

Ia - procainamide

Answer 6

• uses: Afib, Wolff-Parkinson White Syndrome, VT “Storm”
• sodium channel blocker but also blocks outward potassium channels
• can cause rashes myalgias, lupus
• Renal Metabolism

Question 7

Ia - Disopyramide

Answer 7

• sodium channel blocker
• VAGOLYTIC: speeds up heart, UNLIKE other channel blockers
• uses: Afib especially in HCM
• anticholinergic side effects: dry mouth, blurred vision, constipation, urinary retention (used less in older men)
• Renal Excretion

Question 8

Ib - Lidocaine

Answer 8

• ONLY IV
• NARROW therapeutic range
• useful as adjunct to amiodarone or sotalol in ventricular arrhythmias
• shortens QT
• LIVER metabolized

Question 9

Ib - Mexilitene

Answer 9

• good agent to use w/ amiodarone or sotalol (transition from lidocaine)
• shortens QT
• pretty much ORAL form of lidocaine
• uses: ventricular arrythmias (TAKE WITH MEALS)
• LIVER metabolized

Question 10

Ic - Propafenone

Answer 10

• sodium channel blocker: use dependent

- good Afib med in WOMEN

Question 11

Ic - Propafenone: adverse effects

Answer 11

• metallic taste, constipation
• some B-blocking properties so can be a problem in asthma & Raynaud’s Syndrome
• CAN RAISE INR IN PATIENTS ON WARFARIN
• MEN get more side effects

Question 12

Ic - Propafenone: metabolism

Answer 12

LIVER

Question 13

Ic - Flecainide

Answer 13

• sodium channel blocker: use dependence

- great drug in HEALTHY PEOPLE

Question 14

Ic - Flecainide: when & when not to give

Answer 14

• uses: PACs, PVCs, outflow tract arrhythmias, Afib

- don’t give: CHF, CAD, FLUTTER

Question 15

Ic - Flecainide: metabolism

Answer 15

• primary renal, some hepatic (p450)

Question 16

III - Sotalol

Answer 16

• potassium channel blocker + B-blocker
• careful in women: late torsades (renal metabolism varies)
• good drug in men already on B-blocker
• uses: Afib, VT, VT Storm

Question 17

III - Dofetilide

Answer 17

• potassium channel blocker
• must ADMIT TO HOSPITAL to start
• many drug interaction limit usefulness except in HEALTHY PEOPLE
• uses: Afib

Question 18

III - Dronedarone

Answer 18

• hyped to be amiodarone w/ out toxicites
• nowhere near as potent
• ONLY indicated for PAF

Question 19

Amiodarone

Answer 19

• Class I, II, II, and Ca++ blocking properties
• BEST DRUG FOR AFib, VT
• toxicities: lungs, thyroid, liver, retina
• CAN EFFECT INR FOR THOSE ON WARFARIN

Question 20

Ranolazine

Answer 20

• developed as antianginal drug
• sodium, potassium, calcium channel blocking properties
• RAID Trial: ranolazine to treat VTs in ICD patients

Question 21

Mechanisms of antiarrhythmias

Answer 21

• automatic: pebble in pond, single focus w/ out circuit

- re entrant: circuit involved