Tolterodine: a new antimuscarinic agent for the treatment of the overactive bladder.

Bladder hyperactivity is a debilitating problem that affects many individuals. A plethora of therapeutic options have been investigated to combat this condition, antimuscarinic therapy being the most widely used. Nevertheless, this medication group has historically been of limited benefit, due to its side-effect profile. Tolterodine is a new muscarinic receptor antagonist that has been shown to be equally effective when compared to oxybutynin. However, the side-effect profile for tolterodine is much better than this commonly used anticholinergic. It has reduced affinity for the salivary glands in animal studies, and, in clinical trials, there has been a reduced incidence of dry mouth with this medication. In Phase III studies, tolterodine has been shown to decrease the number of micturitions per day, decrease the number of incontinence episodes per day and increase the mean volume voided per micturition. The maximal effect of this medication may not be seen for 6 - 8 weeks after initiation of the drug although the exact explanation for this finding has yet to be completely elucidated. The recommended dose is 2 mg b.i.d., which should be adjusted for those with liver failure or those on drugs that inhibit the cytochrome P450 isoenzyme known as CYP3A4. In summary, tolterodine is an effective well-tolerated antimuscarinic which should be considered as a first-line treatment due to its more favourable side-effect profile when than other available medications.