Intravesical Botulinum Toxin for the Treatment of Overactive Bladder

The prevalence of overactive bladder (OAB) (defined as urinary urgency accompanied by frequency and nocturia, with or without urgency urinary incontinence) in general population is over 16%, and it increases with age in both sexes. The mainstay of pharmacological treatment of OAB according to EAU guidelines is anticholinergics and mirabegron (antagonist of beta-3 receptors). However, these drugs may be not effective and/or well tolerated in some patients mainly due to unpleasant side effects such as dry mouth, constipation or blurry vision. Botulinum toxin (BTX) is a neurotoxin produced by bacterium Clostridium botulinum, which after endocytosis in neuromuscular junction could cleave SNARE proteins which leads to interruption of acetylcholine release from presynaptic motor neurons and finally inhibits muscle contraction. OnabotulinumtoxinA (Botox) is administered into the detrusor muscle during rigid or flexible cystoscopy usually in a dose of 100 U in patients with idiopathic OAB and 200 U in patients with neurogenic bladder usually in local analgesia. Patients must be informed that routinely onabotulinumtoxinA shows a full therapeutic effect after approximately 1–2 weeks and the duration of improvement is estimated for 4–10 months. The only one officially registered botulinum toxin A for the treatment of idiopathic OAB and neurogenic bladder is onabotulinumtoxinA. It has been proven in several clinical trials that in majority of patients suffering from OAB refractory to behavioural and oral therapies (anticholinergics or/and mirabegron), 100 U dose is sufficient to achieve clinically meaningful improvement with relatively low incidence of undesired side effects such as urinary retention and bladder infection after treatment.