Urinary Obstruction Medication

Updated: Feb 23, 2016
  • Author: Michael A Policastro, MD; Chief Editor: Erik D Schraga, MD  more...
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Medication

Medication Summary

Medical therapy for benign prostate hypertrophy (BPH) has provided a very successful alternative to surgical therapy, whose risks include anesthesia, infection, impotence, incontinence, consistent failure to restore normal flow, and frequent necessity for retreatment.

Medical therapy should not be offered to individuals presenting with absolute indications for surgical intervention.

Indications for surgical prostatectomy are recurrent urinary retention, recurrent UTIs, renal insufficiency, bladder calculi, and recurrent gross hematuria.

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Alpha1-adrenoceptor antagonists

Class Summary

The rationale for alpha-blockers in the treatment of BPH is based on the fact that smooth muscle accounts for 40% of the hypertrophied prostatic mass. The basal tone of prostatic smooth muscle is increased significantly by stimulation of alpha1-adrenergic receptors. Alpha-blockers relieve bladder obstruction from BPH by decreasing tonic contraction of prostatic smooth muscle.

Recent molecular studies have identified 3 subtypes of alpha1 receptors. The alpha1-AR subtype is specific for prostatic smooth muscle. Tamsulosin is a selective alpha1-AR antagonist. Recently, a new alpha1-AR antagonist, silodosin (Rapaflo), was approved.

Prazosin (Minipress)

Treats prostatic hypertrophy. Improves urine flow rates by relaxing smooth muscle. This relaxation produced by blocking alpha1-adrenoceptors in bladder neck and prostate. When increasing dosages, give first dose of each increment at bedtime to reduce syncopal episodes. Although doses >20 mg/d usually do not increase efficacy, some patients may benefit from doses as high as 40 mg/d.

Terazosin (Hytrin)

Quinazoline compound that counteracts alpha1-induced adrenergic contractions of bladder neck, facilitating urinary flow in presence of BPH.

Tamsulosin (Flomax)

Selective alpha1-antagonist for treatment of BPH.

Alfuzosin (UroXatral)

Alpha1-adrenoceptors blocker in the prostate. Blockade of adrenoceptors may cause smooth muscles in bladder neck and prostate to relax, resulting in improvement in urine flow rate and reduction in symptoms of BPH.

Silodosin (Rapaflo)

Selectively antagonizes postsynaptic alpha1-adrenergic receptors in prostate, bladder base, prostatic capsule, and prostatic urethra. This action induces smooth muscle relaxation and improves urine flow. Indicated for signs and symptoms of benign prostatic hyperplasia.

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