Monitoring amiodarone therapy, especially when amiodarone is coadministered with other drugs that may interact
Evaluating possible amiodarone toxicity
Assessing patient compliance
Liquid Chromatography Mass Spectrometry (LC-MS/MS)
Amiodarone (Cordarone)
Cordarone (Amiodarone)
Desethylamiodarone
Pacerone (Amiodarone Hydrochloride)
Serum Red
Supplies: Sarstedt Aliquot Tube, 5 mL (T914)
Collection Container/Tube: Red top (serum gel/SST are not acceptable)
Submission Container/Tube: Plastic vial
Specimen Volume: 1.5 mL
Collection Instructions:
1. Draw blood no sooner than 12 hours (trough value) after last dose or immediately before next scheduled dose.
2. Centrifuge and aliquot serum into a plastic vial within 2 hours of collection.
If not ordering electronically, complete, print, and send a one of the following with the specimen:
-Therapeutics Test Request (T831)
-Cardiovascular Test Request (T724)
0.5 mL
Gross hemolysis | OK |
Gross lipemia | OK |
Gross icterus | OK |
Specimen Type | Temperature | Time | Special Container |
---|---|---|---|
Serum Red | Refrigerated (preferred) | 28 days | |
Frozen | 28 days | ||
Ambient | 24 hours |
Monitoring amiodarone therapy, especially when amiodarone is coadministered with other drugs that may interact
Evaluating possible amiodarone toxicity
Assessing patient compliance
Amiodarone is an antiarrhythmic agent used to treat life-threatening arrhythmias; it is typically categorized as a Class III drug (antiarrhythmic agents that are potassium channel blockers) but shows several mechanisms of action. The US Food and Drug Administration approved the use of amiodarone for recurrent ventricular fibrillation and recurrent hemodynamically unstable ventricular tachycardia only after demonstrating lack of response to other antiarrhythmics, but more recent studies have shown amiodarone to be the antiarrhythmic agent of choice for many situations, including atrial fibrillation.(1)
Amiodarone can be administered orally or intravenously for cardiac rhythm control. It is approximately 95% protein bound in blood, with a volume of distribution of 60 L/kg. Amiodarone elimination is quite prolonged, with a half-life of 26-107 days for oral, chronic dosing. Cytochrome P450 (CYP) 3A4 converts amiodarone to its equally active metabolite, N-desethylamiodarone (DEA), which displays very similar pharmacokinetics and serum concentrations compared with the parent drug.(2) Current therapeutic ranges are based solely on amiodarone, but most individuals will have roughly equivalent concentrations of DEA at steady state.(3)
Numerous side effects have been associated with amiodarone. The most common adverse effect is disruption of thyroid function (hypo- or hyperthyroidism) due to amiodarone's structural similarity to thyroid hormones. Neurological and gastrointestinal toxicities are concentration-dependent, whereas thyroid dysfunction, pulmonary fibrosis, and hepatotoxicity are more loosely linked to drug concentration. There is significant potential for drug interactions involving amiodarone, including several other cardioactive drugs (eg, digoxin, verapamil, class I antiarrhythmics [sodium channel blockers]), warfarin, statins, and CYP3A4 substrates.
AMIODARONE
Trough Value
0.5-2.0 mcg/mL: Therapeutic concentration
>2.5 mcg/mL: Toxic concentration
DESETHYLAMIODARONE
No therapeutic range established for desethylamiodarone; activity and serum concentration are similar to parent drug.
Clinical effects generally require serum concentrations above 0.5 mcg/mL.
Increased risk of toxicity is associated with amiodarone concentrations above 2.5 mcg/mL.
Although therapeutic and toxic ranges are based only on the parent drug, the active metabolite N-desethylamiodarone should be present in similar concentrations to amiodarone.
Numerous drug interactions have been observed for amiodarone. Clinical follow-up is essential for optimal use of amiodarone. Therapeutic drug monitoring for amiodarone and coadministered medications is highly recommended.
Specimens that are obtained from gel tubes or anticoagulate collections can cause assay interference.
1. Goldschlager N, Epstein AE, Naccarelli GV, et al. A practical guide for clinicians who treat patients with amiodarone: 2007. Heart Rhythm. 2007;4(9):1250-1259
2. Klotz U. Antiarrhythmics: elimination and dosage considerations in hepatic impairment. Clin Pharmacokinet. 2007;46(12):985-996
3. Campbell TJ, Williams KM. Therapeutic drug monitoring: antiarrhythmic drugs. Br J Clin Pharmacol. 2001;52 Suppl1(Suppl 1):21S-34S
4. Milone MC, Shaw LM. Therapeutic drugs and their management. In: Rifai N, Chiu RWK, Young I, Burnham CAD, Wittwer CT, eds. Tietz Textbook of Laboratory Medicine. 7th ed. Elsevier; 2023:420-453
Protein is precipitated from serum and following centrifugation the supernatant is diluted and analyzed by liquid chromatography tandem mass spectrometry.(Unpublished Mayo method)
Monday through Friday
This test was developed and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. It has not been cleared or approved by the US Food and Drug Administration.
80151
Test Id | Test Order Name | Order LOINC Value |
---|---|---|
AMIO | Amiodarone, S | 55152-3 |
Result Id | Test Result Name |
Result LOINC Value
Applies only to results expressed in units of measure originally reported by the performing laboratory. These values do not apply to results that are converted to other units of measure.
|
---|---|---|
9247 | Amiodarone, S | 3330-8 |
2485 | Desethylamiodarone | 6774-4 |