Tolterodine diol impurit

Tolterodine diol impurity is a dihydroxylated derivative of the parent anticholinergic drug Tolterodine, featuring two adjacent hydroxyl groups substituted on the thienylmethylene moiety. This structural modification introduces vicinal diol functionality, altering the compound's polarity and hydrogen-bonding capacity relative to the parent. The impurity arises via oxidative degradation of the thienylmethylene bridge under alkaline conditions, leading to cleavage and hydroxylation. It serves as a critical HPLC reference standard for quantifying this specific degradation product in Tolterodine-based pharmaceuticals.