Tolterodine is a competitive muscarinic receptor antagonist that shows in v
ivo selectivity for the bladder over the salivary glands compared with oxyb
utinin.
Results of randomised double-blind placebo-controlled studies indicate that
tolterodine 4 mg/day (administered as immediate-release tablets 2 mg twice
daily or extended-release capsules 4 mg daily) is superior to placebo in i
mproving micturition diary variables in patients with overactive bladder. M
oreover, tolterodine 2 mg twice daily is as effective as oxybutynin 5 mg 3
times daily. Maximum treatment effects with both drugs occurred after 5 to
8 weeks of treatment and improvements were maintained during long term trea
tment for up to 24 months.
In a pooled analysis of four 12-week studies, equivalent and significant re
ductions in micturition frequency (-2.3 and -2.0 vs -1.4, p < 0.001) and th
e incidence of urge incontinence episodes (-1.6 and -1.8 vs -1.1, p < 0.05)
were reported fur tolterodine 2 mg twice daily and oxybutynin 5 mg 3 times
daily compared with placebo. Functional bladder capacity was also signific
antly increased.
Improvements in patient perceptions of their urgency symptoms and of proble
ms caused by their bladder condition were significantly greater during trea
tment with tolterodine than with placebo,
Tolterodine was generally well tolerated in clinical trials of up to 24 mon
ths' duration. Dry mouth was the most frequent adverse event, The incidence
(40 vs 78%, p < 0.001) and intensity of this event was lower with tolterod
ine 2 mg twice daily than oxybutynin 5 mg 3 times daily. Additionally, a 23
% lower incidence of dry mouth was reported with once daily extended-releas
e tolterodine capsules than with twice daily immediate-release tablets (p <
0.02). The incidence of adverse CNS events with tolterodine was low and si
milar to that of placebo, Tolterodine was well tolerated in elderly patient
s and no serious tolerability concerns were identified.