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What are alpha blockers

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Overview of alpha blockers 

Alpha blockers interferes the transfer of messages to specific parts of the body. They are also known as alpha adrenergic blocking agents. 

The alpha blockers attach themselves to the molecules that serve as receptors for certain chemical messages thereby preventing the chemical messages from reaching its target. The molecules to which the alpha blockers get attached to are known as alpha receptors. These alpha receptors are predominantly found in blood vessels, in the prostate, and in special blood pressure sensors called baroreceptors.

Effects of alpha blockers

The binding of alpha blockers with alpha receptors causes relaxation and decrease in blood pressure.

They reduce bladder outlet obstruction by relaxing the smooth muscle in the bladder neck and prostate gland. Some older men who suffer from hypertension as well as prostate enlargement can take alpha blockers to get relief from both the ailments. Usually patients are advised to take alpha blockers before going to bed.

Uses of alpha blockers

Alpha blockers are usually taken to treat the conditions listed below:

High blood pressure

benign prostatic hyperplasia

Adrenal gland tumors also known as Pheochromocytoma, which is a type of hormone-secreting tumor

Raynaud's disease: Circulatory conditions like Raynaud's disease

Peripheral artery disease with poor circulation, usually in the legs

Scleroderma: Hardening and thickening of the skin

Alpha blockers are primarily used to treat high blood pressure. However, they are not preferred as the first line of treatment. They are usually used in combination with other drugs like diuretics for treating very high blood pressure situations that are difficult to control.


Common Alpha blockers

Though a number of alpha blockers are available, the most commonly prescribed ones are:

  • Doxazosin (Cardura)
  • Phentolamine
  • Tamsulosin (Flomax)
  • Terazosin

The other types of alpha blockers are mainly used under special circumstances or controlled hospital settings.

Side effects of alpha blockers  

The common side effects of alpha blockers are:

  • Runny nose
  • Dizziness 
  • Decrease in semen

Sometimes they also causes a sudden drop in blood pressure. Patients on alpha blockers are warned against driving or performing any dangerous tasks.

People on alpha blockers may also experience the following side effects:

  • Liver toxicity
  • Priapism which is an abnormally persistent erection of the penis. During priapism, the erection remains even in the absence of sexual desire.
  • Arrhythmias which is an abnormal heart rhythm due to electrical disturbances in the upper chambers of the heart known as atria.
  • Dizziness
  • Decreased blood cell counts (red, white, and platelets)
  • Drowsiness
  • Lupus erythematosus which is a chronic autoimmune disorder that affects the skin, joints, kidneys, and other organs.

Drug-drug Interactions of alpha blockers 

Some of the drug interactions of alpha blockers are:

The first dose of  alpha-1 antagonists taken concomitantly with beta blockers may result in exaggerated hypotensive response. This occurs due to the suppression of the beta-mediated compensatory mechanism of increased heart rate in response to alpha blockade.

Patients are advised against taking PDE5 inhibitors along with alpha blockers. PDE5 inhibitors and alpha-adrenergic blocking agents are both vasodilators with blood pressure lowering effects. So when they are taken together, an additive effect on blood pressure may result leading to symptomatic hypotension causing dizziness, light headedness, as well as fainting. Examples of PDE5 inhibitors are VIAGRA, CIALIS, LAVITRA, REVATIO, and STAXYN.

Next page: Beta blockers

Written by: Healthplus24 team
Date last Updated: July 31, 2012