Which medications in the drug class Alpha-Adrenergic Blockers are used in the treatment of Benign Prostatic Hyperplasia (BPH)?

Updated: Feb 19, 2021
  • Author: Levi A Deters, MD; Chief Editor: Edward David Kim, MD, FACS  more...
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Answer

Alpha-Adrenergic Blockers

These agents block effects of postganglionic synapses at the smooth muscle and exocrine glands.

Phenoxybenzamine (Dibenzyline)

Phenoxybenzamine is a nonselective alpha-adrenergic receptor blocker that antagonizes both alpha-1 and alpha-2 receptors. This nonselectivity leads to a higher incidence of adverse effects, which has led to decreased use of this agent in clinical settings. Phenoxybenzamine induces subjective improvement in urinary flow rates when compared with placebo. It may improve daytime and nighttime urinary frequency. Symptoms improve in 75% of patients.

Prazosin (Minipress)

Prazosin is currently approved for the treatment of hypertension. Prazosin improves urine flow rates by relaxing smooth muscle. Relaxation is produced by blocking alpha-1 adrenoreceptors in the bladder neck and prostate. The advantage of prazosin over nonselective alpha-adrenergic blockers includes a lower incidence of adverse effects. Because of availability of longer-acting, once-daily selective agents, however, the clinical utility of prazosin for BPH has been reduced.

Prazosin improves urinary flow rate and frequency of micturition. Subjective improvement is observed in 82% of patients treated. When increasing dosages, administer the first dose of each increment at bedtime to reduce syncopal episodes. Although doses above 20 mg/d do not usually increase efficacy, some patients may benefit from up to 40 mg/d.

Alfuzosin (UroXatral)

Alfuzosin is indicated for the treatment of the signs and symptoms of BPH. Alfuzosin is an alpha-1 blocker of adrenoreceptors in the prostate. Blockade of adrenoreceptors may cause smooth muscles in the bladder neck and prostate to relax, resulting in improvement in urine flow rate and reduction in symptoms of BPH.

Indoramin

This agent is not available in the United States. Indoramin improves urine flow rates by blocking alpha-1 adrenoreceptors in the bladder neck and prostate, thus relaxing smooth muscle in those sites. Indoramin also reduces the frequency of micturition.

The advantage of indoramin over nonselective alpha-adrenergic blockers includes lower incidence of adverse effects. Because of availability of longer-acting, once-daily selective agents, clinical utility of this agent for BPH has been reduced.

Terazosin (Hytrin)

Terazosin is a quinazoline compound that counteracts alpha1-induced adrenergic contractions of bladder neck, facilitating urinary flow in the presence of BPH. It is indicated for the treatment of symptomatic BPH and hypertension. Its effect on voiding symptoms and flow rates is dose-dependent. It improves irritative and obstructive voiding symptoms. Improvement in flow rate is objective. A Hytrin starter pack is available for easy dosing progression to 5 mg.

Doxazosin (Cardura, Cardura XL)

Doxazosin is indicated for the treatment of urinary outflow obstruction and irritative symptoms associated with BPH and hypertension. It inhibits postsynaptic alpha-adrenergic receptors, resulting in vasodilation of veins and arterioles and a decrease in total peripheral resistance and blood pressure. It is a long-acting alpha1-blocking agent with a profile similar to that of terazosin. Doxazosin improves irritative and obstructive voiding symptoms.

Tamsulosin (Flomax)

Tamsulosin is indicated for the treatment of the signs and symptoms of BPH. It is an alpha-adrenergic blocker specifically targeted to alpha-1 receptors. Tamsulosin has the advantage of producing relatively less orthostatic hypotension; it requires no gradual up-titration from the initial dosage. It inhibits postsynaptic alpha-adrenergic receptors, resulting in vasodilation of veins and arterioles and a decrease in total peripheral resistance and blood pressure. It improves irritative and obstructive voiding symptoms.

Silodosin (Rapaflo)

Silodosin is indicated for the treatment of the signs and symptoms of BPH. Silodosin selectively antagonizes postsynaptic alpha1-adrenergic receptors in the prostate, bladder base, prostatic capsule, and prostatic urethra. This action induces smooth muscle relaxation and improves urine flow.


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