Which anticholinergic drug regimen is most effective for overactive bladder?
Tolterodine (Detrol) is as effective as immediate-release oxybutynin (Ditropan) and causes less dry mouth. A dose of 1 mg tolterodine twice daily is as effective as higher dosages of tolterodine. Extended-release preparations have less risk of dry mouth but are more expensive.
Overactive bladder syndrome is characterized by the sensation of urgency to urinate, sometimes with involuntary leakage (urge incontinence), with no metabolic, mechanic or neurologic cause. Most patients also have frequency and nocturia. It is thought to be caused by an overactive detrusor muscle surrounding the bladder. Overactive bladder syndrome can cause significant discomfort and is more common in older persons.
Options for treatment include nonpharmacologic approaches such as adjusting urine output to 1 to 1.5 L daily, urge-suppression training, bladder retraining, and prompted voiding. Drug treatments include oxybutynin, tolterodine, propantheline (Pro-banthine), dicyclomine (Bentyl), and tricyclic antidepressants.1
In a 2002 Cochrane review,2 Hay-Smith and colleagues determined that, compared with placebo, anticholinergic medications produce a statistically significant improvement in symptoms. To determine which anticholinergic medication regimen is most effective, Hay-Smith and colleagues searched for randomized controlled trials that compared anticholinergic drugs in adults with overactive bladder symptoms.
The two most studied drugs were oxybutynin and tolterodine. In studies comparing the abilities of tolterodine and oxybutynin in reducing leakage episodes and micturitions, the two drugs were similar in effect. However, patients receiving tolterodine were less likely to withdraw because of adverse events (7 versus 12 percent, respectively) and had one half to one third the risk of dry mouth. In addition, 1 mg of tolterodine twice daily was as effective as the more standard dosage of 2 mg twice daily and caused fewer adverse effects. Limited data showed extended-release preparations were equally as effective as immediate-release preparations with fewer adverse effects.
Tolterodine and oxybutynin are available in the following forms: tolterodine immediate-release, 1- and 2-mg capsules; tolterodine extended-release, 2- and 4-mg capsules; oxybutynin immediate-release, 5-mg tablets and 5-mg (5-mL) syrup; oxybutynin extended-release, 5-mg tablets and a transdermal patch that delivers 3.9 mg daily.