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

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.

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.

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 a 10% topical gel formulation of the muscarinic receptor antagonist oxybutynin chloride (Gelnique - Watson) for treatment of overactive bladder. Oxybutynin is also available for this indication as oral tablets, an oral syrup and a transdermal patch.

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.

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.