Recent clinical studies of new pharmacologic agents and their efficacy in the treatment of incontinence.
Two agents for the control of overactive bladder-tolterodine (TOL) and extended-release oxybutynin (Oxy-XL)-have been evaluated in a number of studies for their efficacy in urge incontinence. Studies have demonstrated that TOL achieved a 20% reduction in the frequency of voiding and a 45% reduction in urge incontinent episodes. Efficacy was comparable between TOL and immediate-release oxybutinin (Oxy-IR), the standard anticholinergic comparator. There is a delay of some weeks in achieving relief with TOL, but thereafter there is a continued decrease in the total number of both micturitions and incontinent episodes in 24 hours. Trials demonstrated that there were no safety concerns at all with TOL. In particular, there was a lower incidence of dry mouth with TOL than with Oxy-IR. Dose-ranging studies established that TOL produced the lowest incidence of side effects while maintaining efficacy. In a long-term, community-use study of Oxy-XL, there was a very low incidence of central nervous system side effects, including mental acuity and memory. Among elderly nursing home patients, Oxy-XL achieved a 90% reduction in weekly urge incontinence episodes and an 86% decrease in pad use. Oxy-XL was shown to cause a significantly lower reduction in salivary output than Oxy-IR and TOL. In a recent head-to-head comparison study, there were significant differences found between Oxy-XL and TOL. Other studies have shown that the administration of Oxy-XL results in a significantly lower production of the metabolites responsible for anticholinergic side effect, particularly dry mouth, than with the standard release form, owing largely to the elimination of a first-pass effect. A long-acting form of TOL resulted in a 53% reduction in incontinent episodes. Both these anticholinergic agents have been shown to have excellent efficacy and tolerability. But the future of OAB therapy lies in targeting other mechanisms responsible for incontinence.
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