Alpha-1 blockers (also called alpha-adrenergic blocking agents) constitute a variety of drugs which block α1-adrenergic receptors in
arteriesand smooth muscles.
These drugs may be used to treat:
benign prostatic hyperplasia(BPH)cite journal |author=Höfner K |title=alpha(1)-Blocker therapy in the nineties: focus on the disease |journal=Prostate Cancer Prostatic Dis. |volume=2 |issue=S4 |pages=S9–S15 |year=1999 |month=December |pmid=12496768 |doi=10.1038/sj.pcan.4500368 |url=]
Lower urinary tract symptoms
Transurethral microwave thermotherapy(TUMT) and Transurethral needle ablation of the prostate(TUNA) procedures
high blood pressure(hypertension). This is not typically the drug of choice unless the patient also has BPH.
symptomsof [http://health.yahoo.com/ency/healthwise/hw72762 non inflammatory chronic pelvic pain syndrome] , a type of prostatitis. As a side effect they may reduce blood pressureand result in lightheadedness.
Examples of alpha blockers
Selective Alpha-1 blockers include:
Doxazosincite journal |author=Yilmaz E, Batislam E, Basar MM, Tuglu D, Ferhat M, Basar H |title=The comparison and efficacy of 3 different alpha1-adrenergic blockers for distal ureteral stones |journal=J. Urol. |volume=173 |issue=6 |pages=2010–2 |year=2005 |month=June |pmid=15879806 |doi=10.1097/01.ju.0000158453.60029.0a |url=] (Cardura)
Non-selective Adrenergic blockers:
Tamsulosin is relatively selective for α1a-adrenergic receptors, which are mainly present in the
prostate. Hence, it may have a more selective action in BPH with minimal effects on blood pressure.
Adverse effects and interactions
By reducing α1-adrenergic activity of the blood vessels, these drugs may cause
hypotension(low blood pressure) and interrupt the baroreflexresponse. In doing so, they may cause dizziness, lightheadedness, or fainting when rising from a lying or sitting posture (known as orthostatic hypotensionor postural hypotension). For this reason, it is generally recommended that alpha blockers should be taken at bedtime. Additionally, the risk of first dose phenomenonmay be reduced by starting at a low dose and titrating upwards as needed.
Because these medications may cause orthostatic hypotension, as well as
hypotensionin general, these agents may interact with other medications that increase risk for hypotension, such as other antihypertensives and vasodilators.
As discussed above, tamsulosin may have less risk for hypotension and orthostatic hypotension due to its selectivity for α1a-adrenergic receptors. On the other hand, the drug (a) elevates risk for floppy iris syndrome, and (b) might show ADRs characteristic of the
* [http://www.drugdigest.org/DD/Comparison/NewComparison/0,10621,5-17,00.html DrugDigest] - Alpha blockers
* [http://www.rxlist.com/cgi/generic2/tamsul_cp.htm RxList.com] - Tamsulosin
Wikimedia Foundation. 2010.
Look at other dictionaries:
alpha-adrenergic blocker — alpha blocker … The new mediacal dictionary
alpha-adrenergic blocker — noun any of various drugs that block alpha adrenergic receptors; used in treating benign prostatic hyperplasia; relaxes the muscles of the prostate and bladder • Syn: ↑alpha blocker, ↑alpha blocker, ↑alpha adrenergic blocking agent • Hypernyms:… … Useful english dictionary
Alpha-2 blocker — Although alpha blocker generally refers to α1 blockers, there are also α2 blockers, which are antagonists to the α2 adrenergic receptor. They are mainly used in research, finding little clinical application.ExamplesExamples include… … Wikipedia
alpha-adrenergic blocker — see alpha blocker … Medical dictionary
Alpha blocker — Alpha blockers (or adrenergic alpha antagonists) are agents that act as antagonists of alpha adrenergic receptors. [MeshName|alpha Adrenergic+Blockers] ClassificationThey can be divided into two classes. * Alpha 1 blockers act at alpha 1… … Wikipedia
alpha blocker — (alpha adrenergic blocker) a drug that prevents the stimulation of alpha adrenergic receptors at the nerve endings of the sympathetic nervous system by noradrenaline and adrenaline: it therefore causes widening of arteries (vasodilatation) and a… … Medical dictionary
alpha blocker — alpha adrenergic blocker a drug that prevents the stimulation of alpha adrenoceptors at the nerve endings of the sympathetic nervous system by noradrenaline and adrenaline: it therefore causes relaxation of smooth muscle, including widening of… … The new mediacal dictionary
alpha-blocker — noun any of various drugs that block alpha adrenergic receptors; used in treating benign prostatic hyperplasia; relaxes the muscles of the prostate and bladder • Syn: ↑alpha blocker, ↑alpha adrenergic blocker, ↑alpha adrenergic blocking agent •… … Useful english dictionary
blocker — noun 1. a football player whose responsibility is to block players attempting to stop an offensive play • Derivationally related forms: ↑block • Hypernyms: ↑football player, ↑footballer 2. a class of drugs that inhibit (block) some biological… … Useful english dictionary
alpha blocker — noun any of various drugs that block alpha adrenergic receptors; used in treating benign prostatic hyperplasia; relaxes the muscles of the prostate and bladder • Syn: ↑alpha blocker, ↑alpha adrenergic blocker, ↑alpha adrenergic blocking agent •… … Useful english dictionary