Cyclobenzaprine with Pazopanib Interaction Details
Brand Names Associated with Cyclobenzaprine
- Amrix®
- Cyclobenzaprine
- Flexeril®
Brand Names Associated with Pazopanib
- Pazopanib
- Votrient®
Medical Content Editor Dr. Brian Staiger, PharmD
Last updated
Dec 20, 2023
Interaction Effect
An increased risk of QT-interval prolongation
Interaction Summary
Cyclobenzaprine is structurally related to tricyclic antidepressants, which are known to prolong the QT interval. In a case report, the combination of fluoxetine and cyclobenzaprine was suspected to have caused asymptomatic QT-interval prolongation in a female patient, which progressed to torsade de pointes and ventricular fibrillation after preoperative administration of droperidol, a drug known to prolong the QT interval and cause torsade de pointes . Due to the potential for additive effects on QT-interval prolongation, the concomitant use of cyclobenzaprine with drugs that prolong the QT interval is not recommended. However, if concurrent use is required, monitor the patient for cardiac arrhythmias and QT-interval prolongation.
Severity
Major
Onset
Unspecified
Evidence
Theoretical
How To Manage Interaction
Cyclobenzaprine is structurally related to tricyclic antidepressants, which are known to prolong the QT interval. Coadministration of cyclobenzaprine with drugs that prolong the QT interval should be avoided due to the potential for additive effects on the QT interval and increased risk of torsade de pointes. However, if concurrent use is required, monitor the patient for cardiac arrhythmias and QT-interval prolongation.
Mechanism Of Interaction
Additive effects on QT-interval prolongation
Literature Reports
A) A 59-year-old woman developed torsade de pointes, progressing to ventricular fibrillation and cardiac arrest, after receiving droperidol during elective Achilles tendon surgery the day after discontinuing cyclobenzaprine. Five days prior to the surgery, her QTc was prolonged at 497 milliseconds (msec); magnesium and potassium were within normal limits. Her home medication regimen, which was discontinued the day prior to surgery, included cyclobenzaprine 10 mg/day and fluoxetine 30 mg/day, as well as amlodipine, diclofenac, and triamterene/hydrochlorothiazide. She was premedicated 45 minutes prior to surgery with droperidol 0.625 mg IV and metoclopramide 10 mg IV. Approximately 1 hour and 45 minutes after the surgery had started, the patient developed ventricular tachycardia consistent with torsade de pointes which progressed into ventricular fibrillation and cardiac arrest. Immediately following cardioversion, the patient's QTc was 500 msec with no evidence of ischemic injury. On postoperative day 1, her QT interval had normalized to 440 msec, which was below her baseline value, and an ECG showed normal sinus rhythm. The patient had no known history of cardiac disease or evidence of risk factors associated with torsade de pointes or other dysrhythmias. All preadmission medications were restarted at discharge, with the exception of cyclobenzaprine .
Cyclobenzaprine Overview
-
Cyclobenzaprine is used with rest, physical therapy, and other measures to relax muscles and relieve pain and discomfort caused by strains, sprains, and other muscle injuries. Cyclobenzaprine is in a class of medications called skeletal muscle relaxants. It works by acting in the brain and nervous system to allow the muscles to relax.
Pazopanib Overview
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Pazopanib is used to treat advanced renal cell carcinoma (RCC, a type of cancer that begins in the cells of the kidneys) in adults. Pazopanib is in a class of medications called kinase inhibitors. It works by slowing or stopping the spread of cancer cells.
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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.
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Information for our drug interactions is compiled from several drug compendia, including:
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.