Canadian Journal of Urology - Volume 23, Supplement 1

© The Canadian Journal of Urology™; 23(Supplement 1); February 2016

volume.

The highest risk of AUR appeared to be in

the first month of treatment but reduced significantly

afterwards.

Other agents

Although not commonly used, tricyclic antidepressants

(TCAs) inhibit muscarinic, alpha adrenergic and

histamineH1 receptors. Studies of animal models have

shown that TCAs can improve bladder volume and

reduce the strength of bladder contractions.

The side

effect profile can be vast and can include dry mouth,

constipation, cardiac arrhythmias, urinary retention

and drowsiness. It should be used with caution

especially when considering combination therapy.

Desmopressin (Nocdurna) acetate has a limited

role in the treatment of OAB. A synthetic form of

the antidiuretic hormone vasopressin, it is mainly

used as treatment in patients with primarily nocturia

due to nocturnal polyuria and nocturnal enuresis.

Studies have assessed the dosage of desmopressin

and it appears that a minimum dose of 25 µg orally

disintegrating desmopressin is effective in women.

Men generally benefit from a higher dose of 50 µg.

In both women and men, these doses significantly

reduced the number of nocturnal voids along with

significant increases in health related quality of life

and sleep quality.

Desmopressin was well tolerated

in both doses. Regardless of dose and gender, care

should be taken to avoid hyponatremia and other

electrolyte disturbances especially in elderly patients

in whom there is a risk of worsening cardiac failure.

Serum sodium levels need to be especially monitored

in elderly patients.

Mirabegron (Myrbetriq) is a beta 3 agonist that is

now used in both males and females with OAB. Since

its mechanism of action is different, the typical side

effects seen of anticholinergics are avoided with the

use of mirabegron. It is generally well tolerated and

the most common adverse effects are hypertension

and headaches, the rates of which are very low. Nitti

et al studied the urodynamic safety and efficacy of

mirabegron in males with co-existing LUTS and

bladder outlet obstruction.

Both 50 mg and 100 mg

doses were assessed in the study population and it

was found that neither dose affected flow and bladder

contractility. Both doses were associated with a

statistically significant reduction in urinary frequency.

Furthermore, the 50 mg dose was associated with a

reduction in urgency episodes.

Hence, mirabegron

can be used in women with OAB and men with OAB

with or without benign prostatic hyperplasia (BPH).

Hormone replacement therapy has been used

in postmenopausal women with OAB. Studies

have looked at combination therapy with estrogen

and an anticholinergic agent like tolterodine with

mixed results.

The long term efficacy of hormone

replacement therapy is not known.

Alpha blockers are generally used to manage

voiding symptoms in men, especially those with

an element of bladder outlet obstruction. OAB is

a common sequelae of chronic obstruction in men

and therefore it is necessary at times to manage both

voiding and storage symptoms in male patients.

Combination therapy with an anticholinergic as well

as an alpha blocker has been assessed in clinical studies

for the treatment of storage and voiding symptoms

in men. The NEPTUNE I and II studies looked at the

combination of solifenacin (Vesicare) and tamsulosin,

where it was found that long term treatment with this

combination for up to 52 weeks was toleratedwell and

provided clinical efficacy and quality of life benefits,

compared to tamsulosin monotherapy.

In patients

who commenced treatment with low PVR volumes,

the risk of AUR is rare.

Botulinum toxin is a potent neurotoxin. Derived

from clostridium botulinum, Botox is given as an

intradetrusor injection in patients with idiopathic

and neurogenic DO. Being an invasive procedure, it

is generally reserved for patients who are refractory

to medical treatment. According to randomized

placebo controlled studies, the adverse effects of Botox

treatment include dysuria, bacteriuria and urinary

retention.

Systemic adverse effects are very rare.

Although tolerated generally well, men have a higher

risk than women of urinary retention following Botox

treatment. Posterior tibial nerve stimulation (PTNS)

and sacral neuromodulation (SNS) may be offered

as third line treatments in carefully selected patients.

Usually, these are patients who have severe refractory

OAB symptoms or those who cannot tolerate medical

therapy.

When to refer

Both female and male patients with OAB can

have treatment initiated by their family physician.

However, patients should be referred to a urologist

when they have refractoryOAB symptoms, hematuria,

recurrent urinary tract infections, large PVR volumes

and complicated neurological conditions.

Summary

Multiple studies have assessed the prevalence of OAB

and the impact it has on quality of life. These studies

have shown that OAB is common in both women

Gender differences in overactive bladder