Open Access Research article

Dose escalation improves therapeutic outcome: post hoc analysis of data from a 12-week, multicentre, double-blind, parallel-group trial of trospium chloride in patients with urinary urge incontinence

Rolf-Hasso Bödeker1, Helmut Madersbacher2, Claudia Neumeister3* and Michael Zellner4

Author Affiliations

1 Department of Statistics, Institute for Medical Informatics, University Clinic Giessen, Giessen, Germany

2 Department of Neurology, University Hospital, Innsbruck, Austria

3 Department of Medical Science/Clinical Research, Dr. R. Pfleger GmbH, Bamberg, Germany

4 Johannesbad Specialist Clinic, Johannesstr. 2, D - 94072 Bad Füssing, Germany

For all author emails, please log on.

BMC Urology 2010, 10:15  doi:10.1186/1471-2490-10-15

Published: 14 September 2010



Flexible dosing of anticholinergics used for overactive bladder (OAB) treatment is a useful strategy in clinical practice for achieving a maximum effective and maximum tolerated level of therapeutic benefit. In this post hoc analysis we evaluated the efficacy and tolerability of trospium chloride treatment for urinary urge incontinence (UUI) with focus on flexible dosing.


The data came from a 12-week, randomised, double-blind, phase IIIb study in which 1658 patients with urinary frequency plus urge incontinence received trospium chloride 15 mg TID (n = 828) or 2.5 mg oxybutynin hydrochloride TID (n = 830). After four weeks, daily doses were doubled and not readjusted in 29.2% (242/828) of patients in the trospium group, and in 23.3% (193/830) in the oxybuytnin group, until the end of treatment. We assessed the absolute reduction in weekly UUI episodes and the change in intensity of dry mouth, recorded in patients' micturition diaries. Adverse events were also evaluated. Statistics were descriptive.


Dose escalation of either trospium or oxybutynin increased reduction in UUI episodes in the population studied. At study end, there were no relevant differences between the "dose adjustment" subgroups and the respective "no dose adjustment" subgroups (trospium: P = 0.249; oxybutynin: P = 0.349). After dose escalation, worsening of dry mouth was higher in both dose adjusted subgroups compared to the respective "no dose adjustment" subgroups (P < 0.001). Worsening of dry mouth was lower in the trospium groups than in the oxybutynin groups (P < 0.001). Adverse events were increased in the dose adjusted subgroups.


Flexible dosing of trospium was proven to be as effective, but better tolerated as the officially approved adjusted dose of oxybutynin.

Trial registration (parent study)

The study was registered with the German Federal Institute for Drugs and Medical Devices (BfArM, Berlin, Germany), registration number 4022383, as required at the time point of planning this study.