Two approaches to Overactive Bladder (OAB)
OAB (over-active bladder) is found in both men and
women and is associated with the symptoms of
urgency, frequency, nocturia and urge incontinence.
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. M2 and M3 are predominate muscarinic
receptors found in the bladder. The anti-muscarinic (Ditropan, Ditropan XL,
Vesicare, Sanctura, Gelnique, Toviaz and Enablex) all work by blocking the
receptor, leading to a reduction in bladder contractions. Because they block
the acetylcholine receptor systemically, they can be associated with
constipation and dry mouth.
Bladder storage is primarily regulated by the sympathetic nervous system
via the neurotransmitter norepinephrine. Norepinephrine released from the
sympathetic nerve activates the adrenergic receptors causing the bladder to
relax and close the external sphincter. There are three types of beta
adrenergic receptors expressed in the bladder. The beta-3 AR makes up
97% of bladder receptors and is predominately responsible for the detrusor muscle relaxation. The
drug Myrbetriq has recently been released and is a Beta 3 adrenergic receptor agonist which leads
to increased relaxation of the bladder. In contrast to the anti-muscarinics which cause constipation
and dry mouth, this is much less common with Myrbetriq which has a small incidence of an increase
in blood pressure. Monitoring is important in patients with a history of hypertension.
A Phase 3 trial in over 400 men and women complaining of OAB symptoms was recently conducted
with 3 arms, Tolterodine ER (Detrol LA) Myrbetriq and placebo arm. The incidence of dry mouth was
5 times higher in the Detrol arm than in the Myrbetriq group (10% vs 2%).
It should be noted in all of the clinical trials with both Myrbetriq and the anti-muscarinics, the
increase in urinary voided volume was typically in the range of only 1 or 2 ounces. Both approaches
do result in a significant decrease in the incidence of urge incontinence.
A few key points that we have found important in treating Over active bladder patients include:
One can use a combination of an anti-muscarinic and Myrbetriq to decrease symptoms of
In contrast to prior thinking, there is a very small incidence of urinary retention with the use of
either anti-muscarinics or Beta-3 agonists. However, caution should be used in men who
really don't have OAB but are already in urinary retention carrying large residuals as this can
only exacerbate the situation. Since most primary care physicians don't have access to a
bladder scan, one can use the tried and true old-fashioned way of simple percussion of the
lower abdomen to see if there is, indeed, significant residual urine.
The use of anti-muscarinics in patients with closed angle glaucoma is a contraindication. In
patients with a history of glaucoma, we typically give the patients a list of the drugs and ask
them to check with their ophthalmologist prior to treatment.
There are a number of tips and coping suggestions in patients with over-active bladder that
include: Timed voiding, reduction in caffeine and alcohol, reduction in fluids prior to bedtime
and Kegel exercises when patients have strong urges to void. All of these suggestions can
help. We do provide the patient with a handout on coping suggestions which we have found
effective. In fact, numerous studies have shown that behavior modification is as effective as
For patients who are unresponsive, an intake and output diary can be of help in determining
how big a factor fluid intake can be, as well as, monitoring actual response to treatment.
It also is important to realize that many patients complain primarily of nocturia. Nocturia can
be a result of numerous urologic as well as non-urologic conditions including CHS, venous
insufficiency, and increased fluid intake at night. This is certainly a case where a voiding diary
also can be of benefit. For patients whose primary complaint is nocturia, DDAVP .1 to .2 mg.
can be used but one must monitor the sodium for hyponatremia.
For patients refractory to either combination or individual drug therapy, there are additional
Percutaneous posterior tibial nerve stimulation involves a small acupuncture sized
needle being placed in the ankle and a minimally perceived current transmitted up to
the spinal lumbosacral nerve center where one can "reprogram" the bladder. This is
indicated for patients unresponsive to oral medication.
For patients with refractory OAB symptoms, interstim therapy can be utilized. But
interstim involves initially a percutaneous followed by implantable leads along with a
stimulator which, markedly suppresses and reduces patient symptoms.
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