The activity of a recent K(
ATP) channel opener, the N-(4-Phenylsulfonylphenyl)-3,3,3-trifluoro-2-hydroxy-2-methylpropionamide (
ZM226600) was investigated on a female rat model of
overactive bladder with outlet obstruction. Both
ZM226600 and
pinacidil instilled into the bladder (10(-7) M, 30 min) or following systemic administration (10, 100 nmol/kg e.v.) almost completely abolished bladder overactivity and improved residual volume and frequency of micturition. However,
pinacidil affected arterial pressure.
Oxybutynin instilled into the bladder (10(-7), 10(-6), 10(-5) M, 30 min) decreased detrusor overactivity by about 16%, 25% and 46% respectively, but also blocked micturition reflexes at highest doses tested.
Oxybutynin reduced detrusor overactivity by about 50% and 80%, after systemic administration (10, 100 nmol/kg e.v.), but also blocked micturition reflexes at the highest dose tested. In conclusion,
ZM226600 is more active than
oxybutynin in reducing bladder overactivity, and it is devoid of vascular side effects observed with
pinacidil. Its short duration of action (about 1 h) is probably the main problem to solve, in order to consider this compound a valid alternative to
antimuscarinics in the
therapy of bladder overactivity.