What is the role of selective alpha-blockers 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

The AUA considers alfuzosin, doxazosin, tamsulosin, and terazosin to be appropriate and effective options for treatment of patients with bothersome, moderate-to-severe LUTS secondary to BPH (AUA-SI score ≥8). Although doxazosin and terazosin are older alpha-blockers that require dose titration and blood pressure monitoring, the AUA considers them reasonable choices, as they are inexpensive, are dosed once daily, and appear to be as effective as tamsulosin and alfuzosin. [1]

The efficacy of doxazosin and terazosin is dose-dependent. Maximum tolerable doses have not been defined for any alpha-blocker; however, the higher the dose, the more likely the adverse events (orthostatic hypotension, dizziness, fatigue, ejaculatory disorder, nasal congestion).

Three subtypes of the alpha-1 receptor have been identified: 1a, 1b, and 1c. Of these, the alpha-1a receptor is most specifically concentrated in the bladder neck and prostate. Provided that the alpha-1a subtype is predominant in the prostate, bladder neck, and urethra, but not in other tissues, drugs that are selective for this receptor may offer a potential therapeutic advantage.

Two alpha-1a receptor–selective blockers are currently available for symptomatic treatment of BPH: tamsulosin and silodosin. The AUA guidelines do not include recommendations regarding silodosin, as no relevant studies had yet been published in the peer-reviewed literature at the time of its review. [1]  A more recent Cochrane systematic review, while noting limitations in the available evidence, concluded that the efficacy of silodosin appears similar to that of tamsulosin, naftopidil, and alfuzosin, but the rate of sexual side effects is likely higher. [14]  

Hellstrom and Sikka reported that the acute administration of tamsulosin affects ejaculatory function and ejaculate volume. Nearly 90% of study subjects experienced decreased ejaculate volume, and approximately 35% experienced anejaculation. In their study, subjects treated with alfuzosin or placebo did not experience anejaculation. [15]  A randomized controlled trial by Pande et al that compared silodosin with tamsulosin in 53 men with BPH found that the two drugs have comparable efficacy; however, retrograde ejaculation was encountered only with silodosin and postural hypotension only with tamsulosin. [16]


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