Effect of controlled-release delivery on the pharmacokinetics of oxybutynin at different dosages: severity-dependent treatment of the overactive bladder

OBJECTIVE To assess the pharmacokinetics of a controlled-release formulation of oxybutynin (OROS®-O, ALZA Corp., Mountain View, CA) at different dosages, compared with immediate-release oxybutynin (IR-O), and to determine the pharmacodynamic properties in the severity-dependent reduction of urge urinary incontinence (UUI). PATIENTS AND METHODS In all, 105 patients were enrolled in this multicentre, randomized, double-blind study. Individual dose titration was used to assess the minimum effective, maximum tolerated or maximum allowed dose of either OROS-O or IR-O. Blood samples were collected during maintenance therapy with frequent sampling to analyse for R-oxybutynin and R-desethyloxybutyn…