Effect of oxybutynin on reflex micturition in the decerebrate dog as determined by urodynamic evaluation

Abstract

The effect of oxybutynin on reflex micturition in the decerebrate dog was investigated by cystometric and striated urethral sphincter EMG studies. Reflex micturition consisting of bladder contraction and relaxation of the striated urethral sphincter occurred when a critical degree of filling was reached in the absence and presence of cumulative doses of 30, 100, and 300 pgikg of oxybutynin. Oxybutynin at doses of 30, 100, and 300 pg/kg produced a significant increase in threshold volume during the collecting phase in a dose-dependent manner. In the urodynamic parameters of the emptying phase considered to be influenced greatly by cholinergic activity there was a small but significant decrease in the maximum bladder pressure only at a dose of 300 pg/kg. The present study supports urodynamically clinical usefulness of oxybutynin for the relief of symptoms associated with detrusor instability and hyperreflexia.