Doxazosin with Vardenafil Interaction Details
Brand Names Associated with Doxazosin
- Cardura®
- Cardura® XL
- Doxazosin
Brand Names Associated with Vardenafil
- Levitra®
- Staxyn®
- Vardenafil
Medical Content Editor Dr. Brian Staiger, PharmD
Last updated
Jan 08, 2024
Interaction Effect
Potentiation of hypotensive effects
Interaction Summary
Studies with vardenafil and alpha-blockers suggest concomitant administration of vardenafil and this drug may potentiate hypotensive effects. Patients should be on a stable dose regimen of this drug prior to beginning treatment with vardenafil. For patients who are on a stable regimen of this drug, start vardenafil therapy at the lowest recommended initial dose of 5 mg (2.5 mg when used concomitantly with certain CYP3A4 inhibitors). Stepwise increase in alpha-blocker dose may be associated with further lowering of blood pressure in patients taking a PDE-5 inhibitor including vardenafil. If concurrent therapy is deemed necessary, consider a time interval between the dosing of vardenafil and an alpha blocker. In patients taking alpha-blockers, do not initiate vardenafil therapy with vardenafil orally disintegrating tablets. Lower doses of vardenafil film-coated tablets should be used as initial therapy in these patients. If needed, consider switching to vardenafil oral disintegrating tablets from vardenafil film-coated tablets in patients being treated with alpha-blockers .
Severity
Major
Onset
Rapid
Evidence
Probable
How To Manage Interaction
The coadministration of an alpha-blocker with vardenafil may result in hypotension as both drugs are vasodilators with blood-pressure-lowering effects. Patients should be on a stable dose regimen of this drug prior to beginning treatment with a phosphodiesterase 5 (PDE-5) inhibitor such as vardenafil. For patients who are on a stable regimen of this drug, start vardenafil therapy at the lowest recommended initial dose of 5 mg (2.5 mg when used concomitantly with certain CYP3A4 inhibitors). Stepwise increase in alpha-blocker dose may be associated with further lowering of blood pressure in patients taking a PDE-5 inhibitor including vardenafil. If concurrent therapy is deemed necessary, consider a time interval between the dosing of vardenafil and an alpha-blocker. In patients taking alpha-blockers, do not initiate vardenafil therapy with vardenafil orally disintegrating tablets. Lower doses of vardenafil film-coated tablets should be used as initial therapy in these patients. If needed, consider switching to vardenafil oral disintegrating tablets from vardenafil film-coated tablets in patients being treated with alpha-blockers .
Mechanism Of Interaction
Additive effects on blood pressure
Literature Reports
A) Hypotension has been reported with 5 mg vardenafil when administered to benign prostatic hyperplasia patients on chronic alpha-blocker therapy in two separate randomized, double blind, crossover studies of tamsulosin 0.4 mg daily (n=21) and terazosin 5 or 10 mg daily (n=21). A decrease in standing systolic blood pressure of more than 30 mmHg was reported in 5 patients who received terazosin and in 2 patients who received tamsulosin, when vardenafil was administered simultaneously. Hypotension was not observed in any patients when vardenafil and terazosin were administered 6 hours apart, but was reported in 1 patient when tamsulosin and vardenafil were separated by 6 hours .
B) One case of hypotension (defined as a decrease from baseline in standing systolic blood pressure of more than 30 mmHg) and 3 cases of dizziness were reported with simultaneous administration of vardenafil 10 mg or 20 mg and tamsulosin 0.4 mg or 0.8 mg daily in a randomized, double blind, 2-period crossover study in patients with benign prostatic hyperplasia (n=23) on stable tamsulosin therapy for 4 weeks or longer .
C) One case of hypotension (defined as a decrease from baseline in standing systolic blood pressure of more than 30 mmHg) and 3 cases of dizziness were reported with single doses of vardenafil 5 mg or 10 mg administered 4 hours after alfuzosin 10 mg daily in a randomized, double-blind, 3-period crossover study in patients with benign prostatic hyperplasia (n=24) treated with a stable dose of alfuzosin for 4 weeks or longer .
Doxazosin Overview
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Doxazosin is used in men to treat the symptoms of an enlarged prostate (benign prostatic hyperplasia or BPH), which include difficulty urinating (hesitation, dribbling, weak stream, and incomplete bladder emptying), painful urination, and urinary frequency and urgency. It is also used alone or in combination with other medications to treat high blood pressure. Doxazosin is in a class of medications called alpha-blockers. It relieves the symptoms of BPH by relaxing the muscles of the bladder and prostate. It lowers blood pressure by relaxing the blood vessels so that blood can flow more easily through the body.
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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.
Vardenafil Overview
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Vardenafil is used to treat erectile dysfunction (impotence; inability to get or keep an erection) in men. Vardenafil is in a class of medications called phosphodiesterase (PDE) inhibitors. It works by increasing blood flow to the penis during sexual stimulation. This increased blood flow can cause an erection. Vardenafil does not cure erectile dysfunction or increase sexual desire. Vardenafil does not prevent pregnancy or the spread of sexually transmitted diseases such as human immunodeficiency virus (HIV).
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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.