Intravesical electromotive administration of oxybutynin in patients with detrusor hyperreflexia unresponsive to standard anticholinergic regimens

Abstract

Purpose: About 15% to 20% of patients with detrusor hyperreflexia do not benefit from oral oxybutynin regimens, frequently because of unpleasant side effects. Several reports indicate that intravesical oxybutynin is effective in many of these patients but there are some who still fail to respond.

Materials and methods: A select group of 10 adults with detrusor hyperreflexia unresponsive to standard oral and intravesical oxybutynin regimens were treated at weekly intervals with 5 mg. oxybutynin orally, or 5 mg. oxybutynin in 100 ml. intravesically for 60 minutes of passive diffusion and for 30 minutes with 5 mA. electrical current. Each treatment (plus oral placebo and 2 intravesical controls) was associated with an 8-hour, full urodynamic monitoring session, and periodic blood and bladder content sampling.

Results: There was no significant objective improvement with oral or intravesical passive diffusion oxybutynin. Conversely there was significant improvement in 5 of 6 objective urodynamic measurements with intravesical electromotive oxybutynin. Plasma profiles were a single peak and decay following oral oxybutynin and 2 distinct peaks with intravesical passive diffusion and electromotive oxybutynin. Area under the curve for intravesical passive diffusion were 709 ng. per 8 hours versus oral 1,485 (p <0.05) versus intravesical electromotive 2,781 (p <0.001). Bladder content samples confirmed oxybutynin absorption. Oral oxybutynin caused anticholinergic side effects in 7 of 10 patients. There were no side effects with intravesical passive diffusion or electromotive administrations.

Conclusions: Accelerated intravesical administration results in greater bioavailability and increased objective benefits without side effects in previously unresponsive patients compared with oral and intravesical passive diffusion oxybutynin administration.