21
Table 14. Dosage and Safety Considerations for Maintenance
of Sinus Rhythm in AF (cont'd)
Drug Usual Doses
Exclude/Use With
Caution
Major Pharmacokinetic
Drug Interactions
Vaughan Williams Class III
Amiodarone Oral:
• 400-600 mg
QD in divided
doses for 2-4 wk;
maintenance
typically 100-
200 mg QD
IV:
• 150 mg over 10
min; then 1 mg/
min for 6 h; then
0.5 mg/min for
18 h or change to
oral dosing ; after
24 h, consider
decreasing dose
to 0.25 mg/min
• Sinus or AV node
dysfunction
• Infranodal
conduction
disease
• Lung disease
• Prolonged QT
interval
• Inhibits most CYPs to
cause drug interaction:
↑concentrations of
warfarin
(↑INR 0%-200%),
statins, many other drugs
• Inhibits P-glycoprotein:
↑digoxin concentration
Dofetilide 125-500 mcg once
every 12 h
• Prolonged QT
interval
• Renal disease
• Hypokalemia
• Hypomagnesemia
• Diuretic therapy
• Avoid other
QT interval-
prolonging drugs
• Primary renal
elimination involving
glomerular filtration and
active tubular secretion:
verapamil, HCTZ,
cimetidine, ketoconazole,
trimethoprim,
prochlorperazine,
and megestrol are
contraindicated;
discontinue amiodarone
≥3 mo before initiation
Dronedarone 400 mg once every
12 h
• Bradycardia
• HF
• Long-standing
persistent AF/
flutter
• Liver disease
• Prolonged QT
interval
• Metabolized by
CYP3A: caution
with inhibitors (e.g.,
verapamil, diltiazem,
ketoconazole, macrolide
antibiotics, protease
inhibitors, grapefruit
juice) and inducers (e.g.,
rifampin, phenobarbital,
phenytoin)
• Inhibits CYP3A,
CYP2D6,
P-glycoprotein:
↑concentrations of
some statins, sirolimus,
tacrolimus, beta blockers,
digoxin
