Medication Update

Christy L. Collard, PharmD, Department of Primary Care, Ralph H. Johnson VA Medical Center, Charleston, SC.

South Med J. 2001;94(11) 

In This Article

Alpha Blockers

Mode of Action

Selective blockade of alpha-1 receptors results in vasodilation. These agents decrease blood pressure by decreasing total peripheral resistance and venous return.


Hypersensitivity to the particular alpha blocker agent.

Adverse Effects

Cardiac effects include orthostatic hypotension, palpitations, bradycardia, and edema. Central nervous system side effects including dizziness, headache, fatigue, and anxiety have been reported. Alpha blockers have been noted to effect cholesterol levels (decrease in total cholesterol, LDL, and triglycerides; increase in HDL). GI effects include nausea, diarrhea, constipation, and vomiting. Genitourinary side effects include nocturia, urinary frequency, impotence, and priapism.

Drug-Drug Interactions

Concomitant use of beta blockers with alpha-1 antagonists may result in an exaggerated hypotensive response to the first dose of the alpha antagonist. This is due to suppression of the beta-mediated compensatory mechanism of increased heart rate in response to alpha blockade. Additive effects on hypotension may occur with concomitant use of verapamil. Cimetidine may exaggerate the hypotensive response of tamulosin secondary to decreased metabolism of tamulosin.

Drug-Food Interactions

Food does not appear to interfere with the bioavialability of these agents.

Available Agents

Doxazosin: Cardura.

Prazosin: Minipress.

Tamulosin: Flomax.

Terazosin: Hytrin.

Recommended Dose

Depends upon the agent chosen.

Dosage Forms Available

Available in different dosage strengths.




  1. DRUGDEX System. Hutchison TA, Shahan DR (ed). MICROMEDEX Inc., Greenwood Village, Colo (Edition expires 2001)

  2. Martindale: The Complete Drug Reference. Sweetman S (ed). London, Pharmaceutical Press. Electronic version.


Throw away in the first place all ambition beyond that of doing the day's work well.

-- William Osler


Comments on Medscape are moderated and should be professional in tone and on topic. You must declare any conflicts of interest related to your comments and responses. Please see our Commenting Guide for further information. We reserve the right to remove posts at our sole discretion.
Post as: