The goals of pharmacotherapy are to create continence, reduce morbidity, and prevent complications.
Anticholinergic medications (eg, oxybutynin, hyoscyamine, tolterodine) may be given to decrease detrusor instability and symptoms of urgency. Intermittent catheterization and anticholinergic management are usually used in combination to accomplish symptom-management goals, to create continence, to eliminate vesicoureteral reflux, to prevent UTIs, and to ensure low bladder-storage pressure. If these measures fail, augmentation cystoplasty should be considered.
Oxybutynin chloride, a tertiary amine muscarinic receptor antagonist, is a nonspecific relaxant on smooth muscles.
Tolterodine is a competitive muscarinic receptor antagonist for overactive bladder. It differs from other anticholinergics by being selective for the urinary bladder over the salivary glands. Tolterodine has high specificity for muscarinic receptors and has minimal activity or affinity for other neurotransmitter receptors and other potential targets (eg, calcium channels).
Propantheline blocks the action of acetylcholine at postganglionic parasympathetic receptor sites.
Hyoscyamine blocks the action of acetylcholine at parasympathetic sites in smooth muscle, secretory glands, and the CNS, which, in turn, has antispasmodic effects. Hyoscyamine is absorbed well by the GI tract. Food does not affect absorption of this drug. Hyoscyamine is available in sublingual form (Levsin SL, Symax SL), conventional tablets (Levsin), and extended-release tablets (Levbid).
Neuromuscular Blockers, Botulinum Toxins
Agents in this class cause presynaptic paralysis of the myoneural junction and reduce abnormal contractions.
OnabotulinumtoxinA injections are used in some patients with overactive bladders and may benefit bladder-augmentation candidates. Botulinum toxin may provide relief of spasticity without the systemic adverse effects of other antispasticity agents. It binds to receptor sites on the motor nerve terminals and, after uptake, inhibits the release of acetylcholine, blocking transmission of impulses in neuromuscular tissue.
In treating adult patients for 1 or more indications, the maximum cumulative dose generally should not exceed 360 U in a 3-month period. The recommended treatment dose of onabotulinumtoxinA is 200 U per treatment, divided into 30 injections of 1 mL.