Current pharmacotherapeutic strategies for overactive bladder

Overactive bladder (OAB) is a chronic, distressing condition characterised by symptoms of urgency (sudden overwhelming urge to urinate) and frequency (urinating more than eight times daily), with or without urge urinary incontinence (sudden involuntary loss of urine). It affects millions of people of all ages and both sexes world wide, with greater prevalence in women and the elderly. The treatment of OAB is aimed at reducing debilitating symptoms, which have a significant effect on all aspects of an individual's quality of life, including social, domestic, psychological, occupational, physical and sexual functioning. Anticholinergic agents are currently recommended as first-line therapy for OAB. Their use results in significant clinical improvement in patients, although a lack of selectivity for receptors in the bladder may lead to troublesome side effects, including dry mouth, blurred vision, somnolence, dizziness and constipation. Recent research efforts have focused on developing drugs with a reduced propensity for causing these problems. Of the available anticholinergic agents, oxybutynin and tolterodine are the most widely used to treat OAB. Studies directly comparing tolterodine immediate-release (IR) with oxybutynin IR have shown that the two agents have similar efficacy. However, tolterodine IR is significantly better tolerated, particularly with respect to the incidence and severity of dry mouth. An extended-release formulation of tolterodine (4 mg capsules) has recently been developed to allow for once-daily dosing. In addition to greater convenience, tolterodine extended-release has shown enhanced efficacy and tolerability compared with tolterodine IR.