Tamsulosin with Tadalafil Interaction Details

Brand Names Associated with Tamsulosin

Brand Names Associated with Tadalafil

Medical Content Editor Dr. Brian Staiger, PharmD
Last updated Nov 11, 2023

Interaction Effect

Potentiation of hypotensive effects

Interaction Summary

Tadalafil (a phosphodiesterase 5 inhibitor) and tamsulosin (an alpha-adrenergic blocker) are both vasodilators with blood pressure lowering effects. Due to the potential additive effects on blood pressure, the concomitant use of tadalafil with tamsulosin is not recommended for the treatment of benign prostatic hyperplasia (BPH). Patients taking tamsulosin for BPH should discontinue tamsulosin at least 1 day before starting tadalafil. If tadalafil is administered with tamsulosin, use caution and initiate tadalafil at the lowest recommended dose in a patient hemodynamically stable on tamsulosin or initiate tamsulosin at the lowest dose in a patient on optimized doses of tadalafil. In a drug-drug interaction study, 28% of healthy subjects taking tadalafil 20 mg in addition to doxazosin 8 mg daily, an alpha-adrenergic antagonist like tamsulosin, experienced clinically significant augmentation of the blood-pressure-lowering effect of doxazosin. However, subjects did not experience any clinically significant effects when a single dose of tadalafil 10 mg or 20 mg was administered with tamsulosin 0.4 mg daily .

Severity

Major

Onset

Rapid

Evidence

Established

How To Manage Interaction

The concomitant use of tadalafil with alpha blockers, such as tamsulosin, for benign prostatic hyperplasia (BPH) is not recommended. Patients taking tamsulosin for BPH should discontinue tamsulosin at least 1 day before starting tadalafil. Use caution when tadalafil for erectile dysfunction (ED) and tamsulosin are coadministered. A patient on tamsulosin must be hemodynamically stable before starting tadalafil, which should be initiated at the lowest recommended dose. For patients taking an optimized dose of tadalafil for ED, initiate tamsulosin at the lowest dose.

Mechanism Of Interaction

Additive hypotensive effects

Literature Reports

A) The coadministration of tadalafil and doxazosin significantly increased the hypotensive effect of doxazosin, whereas the coadministration of tadalafil and tamsulosin had no such effect. Two randomized, double-blind, placebo-controlled, crossover studies, each conducted in 18 healthy men, evaluated the hemodynamic interaction between tadalafil and 2 alpha-adrenergic antagonists, doxazosin and tamsulosin. In the doxazosin protocol, subjects were given doxazosin 8 mg daily for a minimum of 7 consecutive days to achieve a steady-state concentration before administration of a single dose of either tadalafil 20 mg or placebo administered simultaneously with doxazosin. A washout period of at least 7 days was utilized to separate the 2 treatment periods. The primary endpoint of these studies was the maximum post-baseline decrease in standing systolic blood pressure (SBP). The mean maximal post-baseline decrease in standing SBP was greater for the doxazosin plus tadalafil treatment arm than it was in the doxazosin plus placebo arm, with a mean difference of 9.8 mmHg (95% confidence interval (CI): 4.1 to 15.5) between the 2 groups .

B) The coadministration of tadalafil and doxazosin significantly increased the hypotensive effect of doxazosin, whereas the coadministration of tadalafil and tamsulosin had no such effect. Two randomized, double-blind, placebo-controlled, crossover studies, each conducted in 18 healthy men, evaluated the hemodynamic interaction between tadalafil and 2 alpha-adrenergic antagonists, doxazosin and tamsulosin. In the tamsulosin protocol, subjects were given tamsulosin 0.4 mg daily for a minimum of 7 consecutive days to achieve a steady-state concentration before administration of a single dose of tadalafil 10 mg or 20 mg, or placebo administered 2 hours after the tamsulosin. The administration of tadalafil 2 hours after tamsulosin was designed to result in the peak plasma concentrations for both drugs to occur simultaneously. A washout period of at least 7 days was utilized to separate the 3 treatment periods. The mean maximal post-baseline decrease in standing SBP was similar after tamsulosin plus tadalafil 10 mg compared with tamsulosin plus placebo (mean difference: 1.7 mmHg, 95% CI: -4.7 to 8.1) and after tamsulosin plus tadalafil 20 mg compared with tamsulosin plus placebo (mean difference: 2.3 mmHg, 95% CI: -4.1 to 8.7) between the groups. No severe or serious adverse events were reported during the tamsulosin study .

Tamsulosin Overview

• Tamsulosin 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. Tamsulosin is in a class of medications called alpha blockers. It works by relaxing the muscles in the prostate and bladder so that urine can flow easily.

Tadalafil Overview

• Tadalafil (Cialis) is used to treat erectile dysfunction (ED, impotence; inability to get or keep an erection), and the symptoms of benign prostatic hyperplasia (BPH; an enlarged prostate) which include difficulty urinating (hesitation, dribbling, weak stream, and incomplete bladder emptying), painful urination, and urinary frequency and urgency in adult men. Tadalafil (Adcirca) is used to improve the ability to exercise in people with pulmonary arterial hypertension (PAH; high blood pressure in the vessels carrying blood to the lungs, causing shortness of breath, dizziness, and tiredness). Tadalafil is in a class of medications called phosphodiesterase (PDE) inhibitors. It works to treat erectile dysfunction by increasing blood flow to the penis during sexual stimulation. This increased blood flow can cause an erection. Tadalafil treats PAH by relaxing the blood vessels in the lungs to allow blood to flow more easily.

• If you are taking tadalafil to treat erectile dysfunction, you should know that it does not cure erectile dysfunction or increase sexual desire. Tadalafil 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:

• 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.