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Oxybutynin and Tolterodine, Extended-Release, Show Low Incidence of Central Nervous System Effects: Presented at AUGS

By Paula Moyer

SAN DIEGO, CA -- August 6, 2004 -- Two anticholinergic therapies, extended-release oxybutynin and extended-release tolterodine, used in the treatment of overactive bladder, are free of central nervous system (CNS) effects, according to findings presented at the 2004 American Urogynecologic Society/Society of Gynecologic Surgeons Joint Scientific Meeting, held here July 28th to August 1st.

These findings should be reassuring to physicians who may have been concerned about reports showing the drugs' potential to cross the blood-brain barrier, said principal investigator Peter K. Sand, MD, director of the Evanston Continence Center, and professor in obstetrics and gynecology at Northwestern University Medical School, both in Evanston, Illinois.

"In this study, both extended-release oxybutynin and extended-release tolterodine were associated with a low incidence of CNS effects," reported Dr. Sand. "Treatment-naïve patients were no more likely report such effects than patients who had received prior treatment."

Because in vitro studies have suggested the potential for anticholinergic medications to cross the blood-brain barrier, Dr. Sand and his coinvestigators wanted to assess the incidence of CNS effects in patients receiving these treatments. They recruited 790 women with overactive bladder, from multiple centers, and randomly assigned them to either 10 mg of extended-release oxybutynin or 4 mg of extended-release tolterodine. The prospective, randomized, double-blind, parallel group design study followed the patients for 12 weeks. The data were complete on 788 patients.

The investigators evaluated the participants at clinic visits at weeks 2, 4, 8, and 12 of the study. Dr. Sand and his investigative team conducted a further subanalysis of treatment-naïve patients and those who had received prior anticholinergic treatment to see if the incidence of CNS effects would differ between the 2 groups.

The incidence of CNS adverse events was low, with no difference between either the treatment groups or the groups by prior treatment status. Among the 391 patients in the oxybutynin group, 211 were treatment-naïve and 180 had received prior anticholinergic treatment. Among the 397 patients in the tolterodine group, 206 were treatment-naïve and 193 had received prior anticholinergic treatment.

Monitored CNS-related symptoms were dizziness, somnolence, insomnia, anxiety, and tremor. Among these patients, 17 patients reported dizziness, 5 each in the oxybutynin groups (2.4% of the treatment-naïve and prior-treatment subgroups) and 7 in the tolterodine group, 2 (1.0%) in the treatment-naïve subgroup and 5 (2.6%) in the prior-treatment subgroup. Somnolence was reported in 11 patients, 3 in the oxybutynin group, consisting of 2 treatment-naïve patients (0.9%) and 1 previously treated patient (0.6%), and 8 in the tolterodine group, consisting of 4 in each subgroup (1.9% for the treatment-naïve subgroup and 2.1%t for the prior treatment subgroup). Five patients in the oxybutynin group reported insomnia, 2 in the treatment-naïve subgroup (0.9%) and 3 in the previously treated subgroup (1.7%); none of the tolterodine patients reported insomnia.

Anxiety was also reported in 5 patients, 3 in the oxybutynin group, including 2 in the treatment-naïve subgroup (0.9%), 1 in the previously treated subgroup (0.6%), and 2 in the tolterodine group, 1 in each subgroup (0.5% for each). Two patients reported tremor, 1 treatment-naïve oxybutynin patient (0.5%) and 1 previously treated tolterodine patient (0.5%).


[Presentation title: Central Nervous System Effects With Two Anticholinergic Medications in Women With Overactive Bladder. Abstract 59]

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