Pressure-flow variables in patients treated with tolterodine for detrusor overactivity

To test the hypothesis that drug treatment which modifies detrusor function (tolterodine) may influence the higher detrusor pressure at urethral opening and closure recorded in patients with detrusor overactivity than in those with stable bladders.

All patients treated with tolterodine in the treatment arm of a phase III, randomized, placebo-controlled trial of tolterodine were eligible for the study. Patients underwent urodynamics before and immediately after 4 weeks of therapy. The detrusor pressure at urethral opening, at maximum flow and at urethral closure, and the maximum bladder capacity and postvoid residual urine volume were recorded from matched urodynamic studies in the trial. Patients with a reduction in urinary frequency of more than two voids per 24 h were defined as responders to treatment and urodynamic data were dichotomised accordingly to allow comparison.

There were no between-group differences in either the detrusor pressure at opening or closure when responders were compared with non-responders. Successful treatment was associated with a statistically significant change in bladder capacity and postvoid residual volume, although the change in residual volume was not clinically significant. Values of detrusor pressure at opening before treatment were greater in non-responders.

The absence of changes in the pressure-flow plot variables is in keeping with previous studies reporting the search for a urodynamic variable which might be used to predict a favourable outcome after drug treatment.