Loratadine with Amiodarone Interaction Details

Brand Names Associated with Loratadine

Brand Names Associated with Amiodarone

Medical Content Editor Dr. Brian Staiger, PharmD
Last updated Feb 27, 2024

Interaction Effect

Increased risk of QT interval prolongation and torsade de pointes

Interaction Summary

Both amiodarone and loratadine are metabolized by CYP3A4 isozymes. Additionally, amiodarone is also a CYP3A4 inhibitor[1]. QT interval prolongation and torsades de pointes has been reported with the coadministration of amiodarone and loratadine [2][3]. Caution is advised if these agents are coadministered. Prior to using these agents concurrently, consider obtaining a baseline ECG and repeating it several hours after ingestion of the first dose. If QT interval prolongation or dispersion is observed, loratadine should be discontinued and rhythm monitoring should be initiated [2].

Severity

Major

Onset

Unspecified

Evidence

Probable

How To Manage Interaction

QT interval prolongation and torsades de pointes with the coadministration of amiodarone and loratadine has been reported[1][2]. Use caution if these agents are coadministered. Prior to using these agents concurrently, consider obtaining a baseline ECG and repeating it several hours after ingestion of the first dose. If QT interval prolongation or dispersion is observed, loratadine should be discontinued and rhythm monitoring should be initiated [2].

Mechanism Of Interaction

Unknown

Literature Reports

A) A case report described QT interval prolongation and torsades de pointes in a 73-year-old woman following concomitant administration of amiodarone and loratadine. The woman, who had a history of hypertension and hyperlipidemia, was on chronic amiodarone therapy (200 mg/day) for paroxysmal atrial fibrillation and had a baseline QT interval of 400 milliseconds. Additional medications included cilaprazil, pravastatin, and warfarin. A few days after receiving loratadine 10 mg/day for a suspected allergic reaction, the patient had a syncopal episode. Physical/neurological exams, and cardiac enzymes, liver, and renal function tests were normal. A transthoracic echocardiogram showed normal systolic left ventricular function, mild left ventricular hypertrophy, and significant diastolic dysfunction. Rhythm monitoring revealed sinus bradycardia, long QT interval (720 milliseconds), with long-short QRS cycles followed by one of multiple episodes of torsades de points (TdP) that were self-terminated. Subsequently, amiodarone and loratadine were discontinued. The patient became asymptomatic over the next 4 days and the QT interval and dispersion returned to normal baseline [2]. A chart review of 6 patients revealed an additional case of syncope and TdP in a 74-year old woman following addition of loratadine (10 mg/day) to chronic amiodarone therapy (200 mg/day) for paroxysmal atrial fibrillation. In this patient, TdP occurred 2 days following ingestion of loratadine [3].

References

1 ) Product Information: CORDARONE(R) oral tablets, amiodarone hcl oral tablets. Wyeth Pharmaceuticals,Inc, Philadelphia, PA, 2006.

2 ) Atar S, Freedberg NA, Antonelli D, et al: Torsades de pointes and QT prolongation due to a combination of loratadine and amiodarone. Pacing Clin Electrophysiol 2003; 26(3):785-786.PubMed Abstract: http://www.ncbi.nlm.nih.gov/...

3 ) Antonelli D, Atar S, Freedberg NA, et al: Torsade de pointes in patients on chronic amiodarone treatment: contributing factors and drug interactions. Isr Med Assoc J 2005; 7(3):163-165.PubMed Abstract: http://www.ncbi.nlm.nih.gov/...

Loratadine Overview

• Loratadine is used to temporarily relieve the symptoms of hay fever (allergy to pollen, dust, or other substances in the air) and other allergies. These symptoms include sneezing, runny nose, and itchy eyes, nose, or throat. Loratadine is also used to treat itching and redness caused by hives. However, loratadine does not prevent hives or other allergic skin reactions. Loratadine is in a class of medications called antihistamines. It works by blocking the action of histamine, a substance in the body that causes allergic symptoms.

• Loratadine is also available in combination with pseudoephedrine (Sudafed, others). This monograph only includes information about the use of loratadine alone. If you are taking the loratadine and pseudoephedrine combination product, read the information on the package label or ask your doctor or pharmacist for more information.

Amiodarone Overview

• Amiodarone is used to treat and prevent certain types of serious, life-threatening ventricular arrhythmias (a certain type of abnormal heart rhythm when other medications did not help or could not be tolerated. Amiodarone is in a class of medications called antiarrhythmics. It works by relaxing overactive heart muscles.

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Definitions

Severity Categories

Contraindicated

These drugs, generally, should not be used together simultaneously due to the high risk of severe adverse effects. Combining these medications can lead to dangerous health outcomes and should be strictly avoided unless otherwise instructed by your provider.

Major

This interaction could result in very serious and potentially life-threatening consequences. If you are taking this drug combination, it is very important to be under close medical supervision to minimize severe side effects and ensure your safety. It may be necessary to change a medication or dosage to prevent harm.

Moderate

This interaction has the potential to worsen your medical condition or alter the effectiveness of your treatment. It's important that you are monitored closely and you potentially may need to make adjustments in your treatment plan or drug dosage to maintain optimal health.

Minor

While this interaction is unlikely to cause significant problems, it could intensify side effects or reduce the effectiveness of one or both medications. Monitoring for changes in symptoms and your condition is recommended, and adjustments may be made if needed to manage any increased or more pronounced side effects.

Onset

Rapid: Onset of drug interaction typically occurs within 24 hours of co-administration.

Delayed: Onset of drug interaction typically occurs more than 24 hours after co-administration.

Evidence

Level of documentation of the interaction.

Established: The interaction is documented and substantiated in peer-reviewed medical literature.

Theoretical: This interaction is not fully supported by current medical evidence or well-documented sources, but it is based on known drug mechanisms, drug effects, and other relevant information.

How To Manage The Interaction

Provides a detailed discussion on how patients and clinicians can approach the identified drug interaction as well as offers guidance on what to expect and strategies to potentially mitigate the effects of the interaction. This may include recommendations on adjusting medication dosages, altering the timing of drug administration, or closely monitoring for specific symptoms.

It's important to note that all medical situations are unique, and management approaches should be tailored to individual circumstances. Patients should always consult their healthcare provider for personalized advice and guidance on managing drug interactions effectively.

Mechanism Of Interaction

The theorized or clinically determined reason (i.e., mechanism) why the drug-drug interaction occurs.

Disclaimer: The information provided on this page is for informational purposes only and should not be considered medical advice. Always consult with a qualified healthcare professional regarding your specific circumstances and medical conditions.

Where Does Our Information Come From?

Information for our drug interactions is compiled from several drug compendia, including:

• Gold Standard Drug Database
• Micromedex
• Lexicomp
• DrugBank

The prescribing information for each drug, as published on DailyMED, is also used. 

Individual drug-drug interaction detail pages contain references specific to that interaction. You can click on the reference number within brackets '[]' to see what reference was utilized.

The information posted is fact-checked by HelloPharmacist clinicians and reviewed quarterly.