Alpha-Blocker Therapy in the Management
of Urological Disorders
Activation of Alpha adrenergic receptors for smooth
muscles causes the smooth muscle to contract. Alpha
blockers, therefore, produce smooth muscle relaxation
by inhibiting contraction of this type of muscle. There
are multiple types of alpha receptors resulting in
different levels of selectivity of the alpha blockers.
Terazosin and Doxazosin are both non-selective alpha
blockers, require dose titration, and have increased side effect of lightheadedness and a drop in
blood pressure. Tamsulosin (Flomax) and its sister drug, Uroxatral (Alfuzosin), are moderately
uro-selective and have less effect on blood pressure but can be associated with altered ejaculation.
Silodosin (Rapaflo) is even more uro-selective, also alters ejaculation, and
reportedly has a quicker onset of action. Reportedly, all are of relative equal
efficacy, however, Rapaflo, again, has a shorter onset of action (3-4 hours).
Regulation of bladder storage and voiding involves both sympathetic and
parasympathetic control. Bladder voiding is primarily regulated by the
parasympathetic nervous system via the neurotransmitter acetylcholine.
Muscarinic receptors (M1-M3-M5) are mediated by acetylcholine in
controlling the contraction of the bladder muscle and relaxation of the
internal sphincter to facilitate voiding.
BPH/Lower Urinary Tract Symptoms (LUTS): Alpha blockers have
been shown to improve urinary symptoms by virtue of relaxation of
the smooth muscle of the prostate and the bladder neck. This results in an increase in urinary
flow, decrease in urinary dribbling, decrease in residual volume, and can improve urinary
frequency and urgency.
Acute urinary retention: A recent randomized placebo controlled study using Rapaflo vs
placebo for three days in men with acute urinary retention (AUR) saw more than twice the
number of men on Rapaflo being able to void successfully over placebo. This is certainly
something to keep in mind for your men who go into acute urinary retention or in those who
you are concerned may do so.
Non-bacterial, non-inflammatory prostatitis: Many men previously diagnosed and/or
treated with antibiotics for prostatitis, also known as chronic pelvic pain syndrome indeed,
may not have a bacterial source. For many of these men, alpha blockers can produce
significant relief of many of the urinary tract symptoms present with this condition, especially
when used in conjunction with hot baths and anti-inflammatories such as Advil.
Ureteral calculi: Although an off- label use, numerous studies show an increased
spontaneous passage of stones with the use of alpha blockers (Medical Expulsion Therapy -
EMT). Please see prior email on "Tis the Season" for further information. The one point to
bring up is the fact that the most rapid onset drug available (Rapaflo) should be tried since it
is more likely to be successful, whereas, Flomax can take 5 to 7 days to produce adequate
Women with feelings of incomplete emptying and slow flow (many of whom in the old days
used to be described as having urethral syndrome) can have marked improvement of their
symptoms with the use of alpha blockers. Again, this is an off- label use, but certainly
something to consider
There are no studies showing that alpha blockers can be used safely in the pediatric population and
certainly we would not recommend it.
CAUTION: Associated with the use of alpha blockers, there is a syndrome called Floppy Iris
Syndrome. This can result in drop in miosis, billowing of the flaccid iris, and iris prolapse during
cataract surgery. Men with planned cataract surgery should avoid the initiation of alpha blockers
until surgery is completed. Floppy Iris Syndrome appears to be lower with older, generic alpha
blockers. Whether the dose/duration or cessation of treatment preoperatively affects floppy iris is
unclear. It is important for all patients on alpha blockers to inform their ophthalmologists of the fact,
although, certainly, ophthalmologists should be well aware of this issue.
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