Guanfacine with Carbamazepine Interaction Details


Brand Names Associated with Guanfacine

  • Guanfacine
  • Intuniv®
  • Tenex®

Brand Names Associated with Carbamazepine

  • Carbamazepine
  • Carbatrol®
  • Epitol®
  • Equetro®
  • Tegretol®
  • Tegretol®-XR
  • Teril®

Medical Content Editor
Last updated Nov 25, 2023


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Interaction Effect

Decreased guanfacine exposure


Interaction Summary

Concomitant use of guanfacine (a CYP3A4 substrate) with a strong CYP3A4 inducer may decrease the guanfacine exposure. When rifampin (a strong CYP3A4 inducer) was coadministered with guanfacine, the guanfacine exposure decreased by about 60%. If coadministration is required, consider making dose adjustments. When initiating guanfacine while the patient is receiving a strong CYP3A4 inducer, increase the guanfacine dose up to double the recommended level. If the patient is already receiving guanfacine and a strong CYP3A4 inducer is added to therapy, increase the guanfacine dose to double the recommended level over 1 to 2 weeks. When continuing guanfacine but discontinuing a strong CYP3A4 inducer, decrease the guanfacine dose to the recommended level over a period of 1 to 2 weeks.


Severity

Moderate


Onset

Delayed


Evidence

Theoretical


How To Manage Interaction

Concomitant use of guanfacine (a CYP3A4 substrate) with a strong CYP3A4 inducer may decrease guanfacine exposure. If coadministration is required, consider making dose adjustments. When initiating guanfacine while the patient is receiving a strong CYP3A4 inducer, increase the guanfacine dose up to double the recommended level. If the patient is already receiving guanfacine and a strong CYP3A4 inducer is added to therapy, increase the guanfacine dose to double the recommended level over 1 to 2 weeks. When continuing guanfacine but discontinuing a strong CYP3A4 inducer, decrease the guanfacine dose to the recommended level over a period of 1 to 2 weeks.


Mechanism Of Interaction

Induction of CYP3A4-mediated metabolism of guanfacine


Literature Reports

A) When rifampin (a strong CYP3A4 inducer) was coadministered with guanfacine, the guanfacine Cmax and AUC decreased by about 60% .

Guanfacine Overview

  • Guanfacine tablets (Tenex) are used alone or in combination with other medications to treat high blood pressure. Guanfacine extended-release (long-acting) tablets (Intuniv) are used as part of a treatment program to control symptoms of attention deficit hyperactivity disorder (ADHD; more difficulty focusing, controlling actions, and remaining still or quiet than other people who are the same age) in children. Guanfacine is in a class of medications called centrally acting alpha2A-adrenergic receptor agonists. Guanfacine treats high blood pressure by decreasing heart rate and relaxing the blood vessels so that blood can flow more easily through the body. Guanfacine extended-release tablets may treat ADHD by affecting the part of the brain that controls attention and impulsivity.

  • High blood pressure is a common condition and when not treated, can cause damage to the brain, heart, blood vessels, kidneys and other parts of the body. Damage to these organs may cause heart disease, a heart attack, heart failure, stroke, kidney failure, loss of vision, and other problems. In addition to taking medication, making lifestyle changes will also help to control your blood pressure. These changes include eating a diet that is low in fat and salt, maintaining a healthy weight, exercising at least 30 minutes most days, not smoking, and using alcohol in moderation.

See More information Regarding Guanfacine

Carbamazepine Overview

  • Carbamazepine is used alone or in combination with other medications to control certain types of seizures in people with epilepsy. It is also used to treat trigeminal neuralgia (a condition that causes facial nerve pain). Carbamazepine extended-release capsules (Equetro brand only) are also used to treat episodes of mania (frenzied, abnormally excited or irritated mood) or mixed episodes (symptoms of mania and depression that happen at the same time) in patients with bipolar I disorder (manic-depressive disorder; a disease that causes episodes of depression, episodes of mania, and other abnormal moods). Carbamazepine is in a class of medications called anticonvulsants. It works by reducing abnormal electrical activity in the brain.

See More information Regarding Carbamazepine

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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:

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.