Extended-release formulations of oxybutynin and tolterodine exhibit similar central nervous system tolerability profiles: A subanalysis of data from the OPERA trial

ObjectiveThis study was undertaken to compare the central nervous system (CNS) tolerability profiles of the extended-release formulations of oxybutynin chloride and tolterodine tartrate in the treatment of women with overactive bladder (OAB), as observed in the OPERA (Overactive bladder: Performance of Extended Release Agents) trial.Study designThe OPERA trial was a randomized, double-blind, active-control comparison of the efficacy and safety of extended-release oxybutynin (10 mg/d) and extended-release tolterodine (4 mg/d) given to 790 women with OAB for 12 weeks. The incidence of reported CNS events was compared between the treatment groups by using the Fisher exact test.ResultsThe incidence of CNS adverse events was 9% and 8% for the oxybutynin and tolterodine treatment groups, respectively. The difference between groups was not statistically significant. All reported CNS adverse events were rated as mild or moderate in severity. There were no serious treatment-related adverse events in either group, and discontinuation because of a CNS adverse event was infrequent.ConclusionThe extended-release formulations of oxybutynin and tolterodine were observed to be associated with a similar low incidence of CNS adverse events, which were mostly mild or moderate in severity.