Class III Antiarrhythmic Agents

Question 1

Sotalol Adverse Effects

Answer 1

TdP within 3 days of initiation, bronchospasm
(β-blocking effects)

Question 2

Sotalol Contraindications

Answer 2

Baseline QTc > 440 ms or CrCl < 40 mL/
min (AF only), LVEF < 40%

Question 3

Sotalol PK

Answer 3

Renally eliminated, half-life 30–40 hr

Question 4

Sotalol
(Betapace) AF Dosing and adjustment

Answer 4

AF maintenance:
> 60 mL/min: 80 mg PO BID
40–60 mL/min: 80 mg PO daily
CI < 40 mL/min

Question 5

Sotalol
(Betapace) VT Dosing and adjustment

Answer 5

> 60 mL/min: 80 mg PO BID
30–60 mL/min: 80 mg PO daily
10–30 mL/min: 80 mg PO every 36–48 hr
< 10 mL/min: 80 mg PO every 48 hr minimum

Question 6

Dofetilide Contraindications

Answer 6

Baseline QTc > 440 ms or CrCl < 20 mL/
min or, CI in patients with intraventricular
conduction delays with baseline QT > 500 msec;
NTE 550 msec

Question 7

Dofetilide PK

Answer 7

Renal and hepatic elimination
Half-life 6–10 hr
Substrate CYP3A4

Question 8

Dofetilide Drug Interactions

Answer 8

CYP3A4 inhibitors and drugs secreted by
kidney (cimetidine, ketoconazole, verapamil,
trimethoprim, prochlorperazine, dolutegravir, megestrol), HCTZ

Question 9

Dofetilide Initiation

Answer 9

Hospitalization mandatory for initiation,
obtain QTc 2–3 hr after each of the first five
doses, reduce 50% if QTc ↑ > 15%; NTE QTc >
500 ms

Question 10

Dofetilide (Tikosyn) Dosing and Adjustments

Answer 10

AF maintenance
> 60 mL/min: 500 mcg PO BID
40–60 mL/min: 250 mcg PO BID
20–40 mL/min: 125 mcg PO BID

Question 11

Ibutilide Adverse Effects

Answer 11

TdP 8%, AV heart block (β-blocking
properties)

Question 12

Ibutilide Contraindications

Answer 12

Baseline QTc > 440 ms, LVEF < 30%,
concomitant AADs

Question 13

Ibutilide PK

Answer 13

Half-life 2–12 hr (avg 6)
CYP3A4 inhibitors

Question 14

Ibutilide
(Corvert) Dosing

Answer 14

AF conversion: 1 mg IV (≥ 60 kg) or 0.01 mg/kg IV (< 60 kg); repeat in 10 min if ineffective (efficacy 47% at 90 min)
not recommended in chronic AF