Overactive Bladder Medication

Updated: Dec 18, 2017
  • Author: Pamela I Ellsworth, MD; Chief Editor: Edward David Kim, MD, FACS  more...
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Medication

Medication Summary

The goals of pharmacotherapy are to improve overactive bladder (OAB) symptoms, reduce morbidity, and prevent complications. Anticholinergics are the first-line agents used to treat OAB. Other treatments approved for use in OAB include the beta3-receptor agonist mirabegron (Myrbetriq) and detrusor injections of onabotulinumtoxinA. Individuals with genital atrophy may benefit from topical estrogen therapy. In select cases of refractory OAB, tricyclic antidepressants may be helpful.

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Anticholinergics

Class Summary

Anticholinergics inhibit the binding of acetylcholine to the muscarinic receptors in the detrusor, thereby suppressing involuntary bladder contractions. This results in an increase in bladder volume voided and a decrease in micturition frequency, sensation of urgency, and number of urge incontinence episodes .

Angioedema of the face, lips, tongue, and/or pharynx has been noted in several of these agents in postmarketing surveillance, including solifenacin, darifenacin, trospium chloride, and fesoterodine. Warnings are noted in the prescribing information for these agents, and if patients experience such symptoms they should seek emergency care.

Tolterodine (Detrol, Detrol LA)

Tolterodine is a nonspecific competitive muscarinic receptor antagonist for OAB. However, it differs from other anticholinergic types in that it has selectivity for urinary bladder over salivary glands. Tolterodine exhibits a high specificity for muscarinic receptors. It has minimal activity or affinity for other neurotransmitter receptors and other potential targets, such as calcium channels.

Oxybutynin (Ditropan XL, Oxytrol, Gelnique)

Oxybutynin inhibits the action of acetylcholine on smooth muscle and has a direct antispasmodic effect on smooth muscles. This, in turn, increases bladder capacity and decreases uninhibited contractions. Oxybutynin is relatively M3, M1 specific.

Trospium

Trospium is a nonspecific quaternary ammonium compound that is excreted intact in the urine and thus is not dependent on the cytochrome P450 system for its metabolism. Being a quarternary amine, it is less likely to penetrate the blood-brain barrier. It antagonizes acetylcholine's effect on muscarinic receptors. Its parasympathetic effect reduces smooth-muscle tone in the bladder. Trospium is indicated to treat symptoms of OAB (eg, urinary incontinence, urgency, frequency). It is available as a single dose, and the extended release formulation should not be taken at night.

Darifenacin (Enablex)

Darifenacin is an extended-release product that elicits competitive muscarinic receptor antagonistic activity. It reduces bladder smooth-muscle contractions. It has high affinity for the M3 receptors and less affinity for other muscarinic receptors. Darifenacin is indicated for OAB with symptoms of urge incontinence, urgency and frequency. Swallow it whole; do not chew, divide, or crush it.

Solifenacin (Vesicare)

Solifenacin is a competitive muscarinic-receptor antagonist that was approved by the US Food and Drug Administration (FDA) in late 2004 for the treatment of OAB with symptoms of urge incontinence, urgency, and urinary frequency. It shares a similar muscarinic receptor affinity as oxybutyinin and is available in 2 doses.

Fesoterodine (Toviaz)

Fesoterodine is the most recent anticholinergic agent to be approved. It is available in 2 doses, and the 8-mg dose has been shown to be superior to tolterodine (Detrol LA) 4mg in the reduction of UUI episodes. It shares a similar muscarinic receptor affinity as tolterodine.

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Beta3-adrenergic agonists

Class Summary

These agents elicit a direct inhibition of afferent nerve firing independent of the relaxing effects on bladder smooth muscle.

Mirabegron (Myrbetriq)

Mirabegron is a beta-3 adrenergic receptor agonist that causes relaxation of the detrusor smooth muscle of the urinary bladder and increases bladder capacity. It is indicated for overactive bladder with symptoms of urge urinary incontinence, urgency, and urinary frequency.

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Neuromuscular Blockers, Botulinum Toxins

Class Summary

Detrusor injections of botulinum neurotoxin type A may be considered for adults with OAB who cannot use or do not adequately respond to anticholinergic medication.

OnabotulinumtoxinA (Botox)

OnabotulinumtoxinA is a neurotoxin derived from Clostridium botulinum. It prevents ACh release from presynaptic membrane, resulting in a temporary calming effect of muscle contractions by blocking the transmission of nerve impulses. The procedure involves multiple injections of a small amount of botox into the muscle of the bladder. The effects are not permanent and thus periodic repeat injections are often needed to maintain response.  Urinary retention is a side effect of the injections and thus individuals must be willing to catheterize intermittently until the retention resolves.

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Tricyclic antidepressants

Class Summary

Tricyclic antidepressants that have been used to treat OAB include imipramine and doxepin. Some agents of this type may decrease bladder contractility. They are not indicated for the first-line treatment of OAB.

Imipramine (Tofranil)

Imipramine is useful in facilitating urine storage. It decreases bladder contractility and increases outlet resistance.

Doxepin

Doxepin increases the concentration of serotonin and norepinephrine in the central nervous system (CNS) by inhibiting their reuptake by presynaptic neuronal membrane. These effects are associated with a decrease in symptoms of depression.

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Hormones

Class Summary

Hormones are used to treat OAB in association with atrophic urethritis and are not recommended as first-line therapies for OAB.

Estrogen (Premarin)

Detrusor overactivity can be associated with atrophic urethritis; topical application of estrogen vaginal cream should be considered in women with symptomatic atrophic urethritis/vaginits.

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