Class Ic Antiarrhythmic Agents

Question 1

Class Ic Caution

Answer 1

Avoid in patients with HF, CAD, or after MI; increased risk of sudden death

Question 2

Propafenone PK

Answer 2

β-blocking properties
PK: Half-life 10–25 hr

Question 3

Propafenone Drug Interactions

Answer 3

Digoxin ↑ by 70%; warfarin ↑ by 50% as
well as drugs that inhibit CYP 2D6, 1A2, 3A4
(increased propafenone)

Question 4

Propafenone (Rythmol) Dosing

Answer 4

AF conversion:
600 mg PO × 1 (450 mg PO × 1 if weight < 70 kg)
AF maintenance:
HCl: 150–300 mg PO every 8–12 hr
HCl (SR): 225–425 mg PO every 12 hr

Question 5

Propafenone Dose Adjustments

Answer 5

Reduce dose 70%–80% in hepatic impairment

Question 6

Flecainide PK/DI

Answer 6

PK: Half-life 10–20 hr
Substrate CYP2D6, CYP1A2
Inhibitor CYP2D6 (Digoxin)

Question 7

Flecainide (Tambocor) Dosing

Answer 7

AF conversion: 300 mg PO × 1
AF maintenance: 50–150 mg PO BID

Question 8

Flecainide Dose Adjustments

Answer 8

Reduce dose by 50% when CrCl < 35 mL/min