Treatment
20
Table 14. Dosage and Safety Considerations for Maintenance
of Sinus Rhythm in AF
Drug Usual Doses
Exclude/Use With
Caution
Major Pharmacokinetic
Drug Interactions
Vaughan Williams Class IA
Disopyramide Immediate release:
• 100-200 mg once
every 6 h
Extended release:
• 200-400 mg once
every 12 h
• HF
• Prolonged QT
interval
• Prostatism,
glaucoma
• Avoid other
QT interval-
prolonging drugs
• Metabolized by
CYP3A4:
caution with inhibitors
(e.g., verapamil,
diltiazem, ketoconazole,
macrolide antibiotics,
protease inhibitors,
grapefruit juice) and
inducers (e.g., rifampin,
phenobarbital,
phenytoin)
Quinidine • 324-648 mg every
8 h
• Prolonged QT
interval
• Diarrhea
• Inhibits CYP2D6:
↑concentrations of
tricyclic antidepressants,
metoprolol,
antipsychotics;
↓efficacy of codeine
• Inhibits P-glycoprotein:
↑digoxin concentration
Vaughan Williams Class IC
Flecainide 50-200 mg once
every 12 h
• Sinus or AV node
dysfunction
• HF
• CAD
• Atrial flutter
• Infranodal
conduction
disease
• Brugada syndrome
• Renal or liver
disease
• Metabolized by
CYP2D6 (inhibitors
include quinidine,
fluoxetine, tricyclics;
also genetically absent in
7%-10% of population)
and renal excretion
(dual impairment
can ↑↑plasma
concentration)
Propafenone Immediate release:
• 150-300 mg once
every 8 h
Extended release:
• 225-425 mg once
every 12 h
• Sinus or AV node
dysfunction
• HF
• CAD
• Atrial flutter
• Infranodal
conduction
disease
• Brugada syndrome
• Liver disease
• Asthma
• Metabolized by
CYP2D6 (inhibitors
include quinidine,
fluoxetine, tricyclics;
also genetically
absent in 7%-10% of
population)—poor
metabolizers have ↑beta
blockade
• Inhibits P-glycoprotein:
↑digoxin concentration
• Inhibits CYP2C9:
↑warfarin concentration
(↑INR 25%)
