Abstract: The present invention provides compositions and methods for administering oxybutynin while minimizing the incidence and or severity of adverse drug experiences associated with oxybutynin therapy. In one aspect, these compositions and methods provide a lower plasma concentration of oxybutynin metabolites, such as N-desethyloxybutynin, which is presumed to be contributing at least in part to some of the adverse drug experiences, while maintaining sufficient oxybutynin plasma concentration to benefit a subject with oxybutynin therapy. The invention also provides isomers of oxybutynin and its metabolites that meet these characteristics of minimized incidence and/or severity of adverse drug experiences, and maintenance of beneficial and effective therapy for overactive bladder.