Guanfacine with Voriconazole Interaction Details
Brand Names Associated with Guanfacine
- Guanfacine
- Intuniv®
- Tenex®
Brand Names Associated with Voriconazole
- Vfend®
- Voriconazole
Medical Content Editor Dr. Brian Staiger, PharmD
Last updated
Nov 08, 2023
Interaction Effect
Increased guanfacine exposure
Interaction Summary
Concomitant use of guanfacine (a CYP3A4 substrate) with a strong CYP3A4 inhibitor may increase the exposure of guanfacine. When ketoconazole (a strong CYP3A4 inhibitor) was coadministered with guanfacine, the guanfacine exposure increased by over 200%. If coadministration is required, dose adjustments are necessary. When initiating guanfacine while the patient is receiving a strong CYP3A4 inhibitor or adding a strong CYP3A4 inhibitor to existing guanfacine therapy, decrease the recommended guanfacine dose by half. If continuing guanfacine while stopping a strong CYP3A4 inhibitor, increase the guanfacine dose to the recommended level.
Severity
Moderate
Onset
Unspecified
Evidence
Theoretical
How To Manage Interaction
Concomitant use of guanfacine (a CYP3A4 substrate) with a strong CYP3A4 inhibitor may increase the exposure of guanfacine. If coadministration is required, dose adjustments are necessary. When initiating guanfacine while the patient is receiving a strong CYP3A4 inhibitor or adding a strong CYP3A4 inhibitor to existing guanfacine therapy, decrease the recommended guanfacine dose by half. If continuing guanfacine while stopping a strong CYP3A4 inhibitor, increase the guanfacine dose to the recommended level.
Mechanism Of Interaction
Inhibition of CYP3A4-mediated metabolism of guanfacine
Literature Reports
A) When ketoconazole (a strong CYP3A4 inhibitor) was coadministered with guanfacine, the guanfacine Cmax and AUC increased by about 2 and 3-fold, respectively .
Guanfacine Overview
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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.
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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.
Voriconazole Overview
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Voriconazole is used in adults and children 2 years of age and older to treat serious fungal infections such as invasive aspergillosis (a fungal infection that begins in the lungs and spreads through the bloodstream to other organs), esophageal candidiasis (a yeast [a type of fungus] infection that may cause white patching in the mouth and throat), and candidemia (a fungal infection in the blood). It is also used to treat certain other fungal infections when other medications will not work for certain patients. Voriconazole is in a class of antifungal medications called triazoles. It works by slowing the growth of the fungi that cause infection.
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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.