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Home / Drugs / Starting with D / Doxazosin

Doxazosin is a quinazoline-derivative that selectively antagonizes postsynaptic α1-adrenergic receptors. It may be used to mild to moderate hypertension and in the management of symptomatic benign prostatic hyperplasia (BPH). α1-Receptors mediate contraction and hypertrophic growth of smooth muscle cells. Antagonism of these receptors leads to smooth muscle relaxation in the peripheral vasculature and prostate gland.
Cardura XL
CategoriesAntineoplastic Agents
Antihypertensive Agents
Vasodilator Agents
Adrenergic alpha-Antagonists
Alpha-adrenergic Blocking Agents
Antihyperplasia Agents
ManufacturersPfizer inc
Pfizer laboratories div pfizer inc
Actavis elizabeth llc
Apotex inc
Dava pharmaceuticals inc
Genpharm inc
Ivax pharmaceuticals inc sub teva pharmaceuticals usa
Kv pharmaceutical co
Mylan pharmaceuticals inc
Pliva inc
Sandoz inc
Teva pharmaceuticals usa inc
Watson laboratories inc
PackagersActavis Group
Advanced Pharmaceutical Services Inc.
Amerisource Health Services Corp.
Apotex Inc.
A-S Medication Solutions LLC
Cardinal Health
DAVA Pharmaceuticals
Dept Health Central Pharmacy
Direct Dispensing Inc.
Dispensing Solutions
Diversified Healthcare Services Inc.
General Injectables and Vaccines Inc.
Golden State Medical Supply Inc.
Heartland Repack Services LLC
International Laboratories Inc.
Ivax Pharmaceuticals
Legacy Pharmaceuticals Packaging LLC
Major Pharmaceuticals
Merrell Pharmaceuticals Inc.
Murfreesboro Pharmaceutical Nursing Supply
Novopharm Ltd.
Nucare Pharmaceuticals Inc.
Palmetto Pharmaceuticals Inc.
Par Pharmaceuticals
Patheon Inc.
Pfizer Inc.
Pharmaceutical Utilization Management Program VA Inc.
Physicians Total Care Inc.
Pliva Inc.
Preferred Pharmaceuticals Inc.
Prepackage Specialists
Prepak Systems Inc.
Redpharm Drug
Remedy Repack
Sandhills Packaging Inc.
Southwood Pharmaceuticals
Stat Rx Usa
Teva Pharmaceutical Industries Ltd.
Torpharm Inc.
Tya Pharmaceuticals
UDL Laboratories
US Pharmaceutical Group
Vangard Labs Inc.
SynonymsDoxazosin mesilate
Doxazosin mesylate


For treatment and management of mild to moderate hypertension and urinary obstruction symptoms caused by BPH.


Doxazosin is an alpha-adrenergic blocking agent used to treat hypertension and benign prostatic hyperplasia. Accordingly, Doxazosin is a selective inhibitor of the alpha1 subtype of alpha adrenergic receptors. In the human prostate, Doxazosin antagonizes phenylephrine (alpha1 agonist)-induced contractions, in vitro, and binds with high affinity to the alpha1c adrenoceptor, which is thought to be the predominant functional type in the prostate. Studies in normal human subjects have shown that Doxazosin competitively antagonized the pressor effects of phenylephrine (an alpha1 agonist) and the systolic pressor effect of norepinephrine. The antihypertensive effect of Doxazosin results from a decrease in systemic vascular resistance and the parent compound Doxazosin is primarily responsible for the antihypertensive activity.

mechanism of action

Doxazosin acts by inhibiting the postsynaptic alpha(1)-adrenoceptors on vascular smooth muscle. This inhibits the vasoconstrictor effect of circulating and locally released catecholamines (epinephrine and norepinephrine), resulting in peripheral vasodilation.


Symptoms of overdose include hypotension. Oral LD50 is greater than 1000 mg/kg in mice and rats.





half life

22 hours

route of elimination

On average only 4.8% of the dose was excreted as unchanged drug in the feces and only a trace of the total radioactivity in the urine was attributed to unchanged drug.

drug interactions

Tadalafil: Tadalafil may enhance the hypotensive effect of Doxazosin. Monitor for hypotension during concomitant therapy.

Tamsulosin: Concomitant use of alpha1-adrenergic antagonists, Tamsulosin and Doxazosin, may result in additive antihypertensive effects. Combination therapy is not recommended.

Treprostinil: Additive hypotensive effect. Monitor antihypertensive therapy during concomitant use.

Vardenafil: Additive hypotensive effects of the PDE5 inhibitor, Vardenafil, and alpha1-blocker, Doxazosin, may occur. Monitor for hypotension during concomitant therapy.