(S)-N-(4-benzoylphenyl)-3,3,3-trifluoro-2-hydroxy-2-methyl-propionamide (ZD6169) is a novel ATP-sensitive potassium channel opener. Bladder activity and selectivity after oral dosing were studied in conscious, normotensive rats and dogs by monitoring cystometric and cardiovascular (CV) parameters. The reference ATP-sensitive K+ channel opener cromakalim was also evaluated in this study. ZD6169 significantly reduced micturition frequency in rats (ED50 = 0.16 mg/kg), but its effect on CV parameters was minimal (ED20 = 30 mg/kg), yielding a selectivity dose ratio of 187. The duration of action was between 7 and 24 hr at doses of 0.3 and 3 mg/kg, but it was more than 24 hr at 10 mg/kg. The ED50 value for bladder activity in dogs was less than 1.0 mg/kg, and the ED20 value for CV activity was slightly greater than 15 mg/kg but less than 20 mg/kg; the selectivity ratio was greater than 15. A significant improvement in bladder compliance was noted in dogs with ZD6169, and the bladder activity in rats was blocked by i.v. glibenclamide (3 mg/kg). Cromakalim had a bladder profile similar to that of ZD6169 but appeared to be more selective for CV parameters. In conclusion, ZENECA ZD6169 is a unique ATP-sensitive K+ channel opener with in vivo selectivity of relaxing bladder smooth muscle. This agent has the potential for treating patients with urge incontinence.