VHA Pharmacy Benefits Management-Strategic Healthcare Group and Medical Advisory Panel
Amiodarone Monitoring
Due to the number of reports to the FDA of serious adverse events with amiodarone, it is recommended that all patients on amiodarone be
reviewed for appropriate monitoring. This form has been developed to assure that a mechanism is in place for documenting the monitoring
requirements.
The information on this form is a compilation of recommendations and may be modified according to clinical practice at the facility.
If there already is an adequate monitoring system in place at the facility, it is not necessary to implement this form.
Examination
Baseline
3 months
6 months
12 months
If Symptoms
Pulmonary Function
a
Chest X-ray
b
Thyroid Panel
c
Liver Panel
ECG
Eye Exam
CBC
Chem-7
Clinical Evaluation
a
Baseline only if underlying pulmonary disease suspected
b
Others have recommend monitoring every 3 to 6 months
c
Some recommend monitoring every 6 months, others periodically
Potential Drug
Interactions
Date Started
a
Date lab f/u: Date lab f/u: Date lab f/u:
Warfarin
INR: INR: INR:
Digoxin
Digoxin: Digoxin: Digoxin:
Antiarrhythmic:
Level: Level: Level:
Phenytoin
PHT: PHT: PHT:
Cyclosporine or
Tacrolimus
Level: Level: Level:
a
Table may be used to document appropriate follow-up when amiodarone or interacting medication initiated
Medications Known to Interact
with Amiodarone
a
Interaction
Recommendations
Warfarin
↑
PT and INR (usually begins within 1 week,
stabilizing after 1 month) due to inhibition of
warfarin metabolism;
↑
bleeding risk
Consider
↓
warfarin dose by 33-50%; monitor
INR weekly for 4 weeks; titrate to goal INR
Digoxin
↑
digoxin concentrations (usually within 1-7
days, progressing over several weeks or
months) by
↓
renal and nonrenal clearance;
may result in toxicity
Consider
↓
digoxin dose by 50%; monitor digoxin
at 2 and 6 weeks; titrate to therapeutic digoxin
level
Antiarrhythmic agents
(quinidine, procainamide,
flecainide)
↑
antiarrhythmic blood levels (within 5-7
days, taking several weeks for maximum
effect) due to
↓
hepatic clearance; may
prolong impulse conduction resulting in
arrhythmias
Monitor ECG intervals;
↓
dose of antiarrhythmic
33-50% (20-33% for procainamide) several days
after start of amiodarone or if already on
amiodarone, initial dose of antiarrhythmic should
be
↓
by 50% of the usual initial dose; or monitor
serum concentrations and adjust dose accordingly
Phenytoin
↑
concentrations of phenytoin (usually within
3-4 weeks) by inhibition of hepatic
metabolism; may result in toxicity
Monitor phenytoin serum concentrations at 2-4
weeks and adjust dose accordingly; amiodarone
levels may
↓
Cyclosporine, Tacrolimus
Clearance
↓
by 50%; may result in toxicity
(renal dysfunction)
Monitor plasma concentrations frequently and
adjust dose accordingly
b-adrenergic blockers, Calcium
antagonists (diltiazem, verapamil)
Possible potentiation of bradycardia, sinus
arrest, AV block
Observe patient carefully for signs of cardiac
toxicity
a
Clinically significant interactions listed; for additional drug interactions, refer to references below.
References:
1. Hansten PD, Horn JR. Drug interactions analysis and management. Vancouver: Applied Therapeutics; 1998
2. Singh BN. Amiodarone: The expanding antiarrhythmic role and how to follow a patient on chronic therapy. Clin Cardiol 1997;20:608-18.
3. Pollack PT. Clinical organ toxicity of antiarrhythmic compounds: ocular and pulmonary manifestations. Am J Cardiol 1999;84:37R-45R.
4. Cordarone
®
(amiodarone) product information. Wyeth Laboratories, Inc; 1998.
5. Pacerone
®
(amiodarone) product information. Upsher-Smith Laboratories, Inc; 1998.
May 2000
