白袍恐懼症

BPH medical treatment

1.    The bladder outlet obstruction of BPH has two components:

(1). A dynamic (physiologic, reversible) component related to the tension of prostatic smooth muscle in the prostate, prostate capsule, and bladder neck.

(2). A fixed (structural) component related to the bulk of the enlarged prostate impinging upon the urethra.

=>Alpha-adrenergic antagonists: more effective for short-term treatment of BPH/LUTS

=>5-alpha-reductase inhibitors: for long-term reduction in prostate volume.

=>Antiandrogens and gonadotropin-releasing hormone (GnRH) agonists: GnRH agonists may be somewhat more effective for BPH/LUTS than the above medications, but the resulting androgen deficiency generally makes their use unacceptable to patients.

2.    Alpha-1-adrenergic antagonists 

(1). Mechanism:

relaxing smooth muscle in the bladder neck, prostate capsule, and prostatic urethra. (dynamic component)

Alpha-1 receptors are abundant in the prostate and base of the bladder, and sparse in the body of the bladder. The density of these receptors is increased in hyperplastic prostatic tissue.

Three alpha-1 adrenoreceptor sub-types have been characterized: 1A, 1B, and 1D.

(2). Side effects and interactions:

Major: orthostatic hypotension and dizziness

Minor: asthenia and nasal congestion

These differential effects on blood pressure by different alpha-1-antagonists may be due to their differential blocking of alpha-1A receptor subtype

3.    5-Alpha-reductase inhibitors: finasteride and dutasteride

(1). Mechanism:

reducing the size of the prostate gland.

5-Alpha-reductase分為type 1和type 2

type 1: present in liver, non-genital skin, and some areas of the brain

type 2: conversion of testosterone to dihydrotestosterone in the prostate, hair follicles, and other androgen-sensitive tissues.

decreased the probability of surgery

The 5-alpha-reductase inhibitors are more effective in men with larger prostates, and their effects on acute urinary retention and reduction in need for surgery require chronic treatment for more than a year.

(2). Side effects

Major: decreased libido and ejaculatory or erectile dysfunction.

PSA concentrations decrease by about 50 percent

5-alpha-reductase inhibitors significantly decrease the incidence of prostate cancer.

4.    Antimuscarinics:

(1). Mechanism:

Bladder contractions are stimulated by acetylcholine effects on muscarinic receptors in smooth muscle of the bladder.

ð  Relief obstructive symptoms

Use of antimuscarinic agents should be restricted to men with low post-void residual volumes.

5.    SUMMARY

1.    Mild to moderate symptoms of BPH => alpha-adrenergic antagonist alone.

2.    Severe symptoms, those with a large prostate (>40 g), and in those who do not get an adequate response to maximal dose monotherapy with an alpha-adrenergic antagonist=> combination treatment with an alpha-adrenergic antagonist and a 5-alpha-reductase inhibitor.

3.      Low post-void residual urine volumes and obstructive symptoms that persist during treatment with an alpha-adrenergic antagonist=> treatment with an antimuscarinic agent