In overactive bladder, involuntary bladder contractions due to detrusor overactivity result in urinary urgency, frequency, nocturia, and incontinence. The prevalence of the disorder increases with age. Nonpharmacologic treatment, including bladder training, urge suppression, pelvic floor muscle exercises, constipation management, modification of fluid intake, and avoidance of dietary irritants such as alcohol and caffeine, should be tried first.

About 60% of men ≥60 years old have clinically relevant prostatic enlargement due to benign prostatic hyperplasia (BPH). The goals of treatment are to decrease lower urinary tract symptoms and to prevent disease progression and complications such as acute urinary retention. The American Urologic Association's guidelines for treatment of BPH were recently updated.

The FDA has approved the selective beta-3 adrenergic agonist vibegron (Gemtesa – Urovant Sciences) for treatment of overactive bladder in adults with symptoms of urge urinary incontinence, urgency, and urinary frequency. It is the second beta-3 agonist to be approved in the US; mirabegron (Myrbetriq) was the first.

The transdermal patch formulation of the anticholinergic drug oxybutynin (Oxytrol – Watson) is now available over the counter (OTC) as Oxytrol for Women (MSD) for use in women with overactive bladder (OAB). It is the first treatment for OAB to become available OTC. Oxybutynin remains available only by prescription for men.

OAB, characterized by symptoms of urgency, frequency, and incontinence with no obvious cause, occurs mainly in older women.1 Behavioral modification, including fluid schedules, timed voiding, pelvic exercises, and urge suppression, is usually tried first.

Anticholinergic drugs such as oxybutynin and tolterodine (Detrol, and others) reduce OAB symptoms by relaxing bladder smooth muscle and inhibiting involuntary detrusor contractions. Dry mouth has been the limiting adverse effect. In clinical studies, the oxybutynin patch was associated with fewer systemic adverse effects, including dry mouth, than the oral drug, but with a high incidence of pruritus at the application site.2

Oxytrol and Oxytrol for Women both deliver 3.9 mg of oxybutynin per 24 hours and are applied every 4 days, but a box of 8 prescription Oxytrol patches costs $320.32,3 while an 8-patch box of OTC Oxytrol for Women costs only $29.99.4

1. EA Gormley et al. Diagnosis and treatment of overactive bladder (non-neurogenic) in adults: AUA/SUFU guideline. J Urol 2012; 188:2455.

2. Oxybutynin transdermal (Oxytrol) for overactive bladder. Med Lett Drugs Ther 2003; 45:38.

3. Wholesale acquisition cost (WAC). Source: $ource® Monthly (Selected from FDB MedKnowledge™) September 5, 2013. Reprinted with permission by FDB, Inc. All rights reserved. ©2013. www.fdbhealth.com/policies/drug-pricing-policy. Actual retail price may be higher.

4. Cost according to drugstore.com. Accessed September 5, 2013.

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The FDA has recently approved intradetrusor injection of onabotulinumtoxinA (Botox – Allergan) for treatment of overactive bladder in patients who cannot tolerate or have an inadequate response to anticholinergic therapy. Botox is also approved by the FDA for use in detrusor overactivity associated with a neurologic condition such as multiple sclerosis or spinal cord injury, and for chronic migraine, upper limb spasticity, axillary hyperhidrosis, cervical dystonia, blepharospasm, strabismus, and cosmetic reduction of wrinkles.

Mirabegron (mir a beg’ ron; Myrbetriq [meer BEH trick] – Astellas), a beta-3 adrenergic agonist, has been approved by the FDA for the treatment of overactive bladder. It is the first beta-3 adrenergic agonist to be approved for any indication in the US. Mirabegron has been marketed in Japan since 2011. OnabotulinumtoxinA (Botox) was also recently approved by the FDA for treatment of overactive bladder and will be reviewed in a future issue.

The FDA has approved the marketing of fesoterodine (Toviaz - Pfizer), a muscarinic receptor antagonist, for treatment of overactive bladder. It is the sixth antimuscarinic drug approved for this indication.

Serious adverse interactions between drugs continue to be reported. Many of these are due to inhibition or induction of cytochrome P450 (CYP) enzymes, particularly CYP3A4. CYP3A is thought to be involved in the metabolism of more than 50 percent of currently prescribed drugs.2 CYP3A4, which is more abundantly expressed than CYP3A5, accounts for most CYP3A activity in vivo.

Solifenacin succinate (VESIcare - Yamanouchi and GlaxoSmithKline) and darifenacin hydrobromide (Enablex - Novartis) have been approved by the FDA for oral treatment of overactive bladder.

A patch formulation of oxybutynin (Oxytrol - Watson) is now available for treatment of overactive bladder. It is claimed to be as effective as the oral drug, with less dry mouth.

The Medical Letter article on Detrol LA and Ditropan XL (vol.43, page 28, April 2, 2001) stated that these drugs should not be used in patients with glaucoma. That statement is misleading because anticholinergic or antimuscarinic drugs present a risk only to patients with untreated angle-closure (also called narrow-angle) glaucoma, which accounts for 10% of glaucomas in the USA. These drugs have no effect on the more common open-angle glaucoma, or on angle-closure glaucoma that has been treated by laser iridectomy.