Evaluate the Safety and Efficacy of TRG-200 KIT in Patients With Refractory Overactive Bladder.

This is an open-label, single-center pilot study designed to evaluate the safety, tolerability, and preliminary efficacy of TRG-200 KIT, an intravesical sustained-release oxybutynin formulation, in adult patients with refractory overactive bladder (OAB). The study includes an adaptive two-stage design with initial dose evaluation of two dose levels (150 mg and 300 mg oxybutynin) followed by expansion using the selected dose. TRG-200 KIT is administered via monthly intravesical instillation and aims to provide prolonged local bladder exposure while minimizing systemic absorption and anticholinergic adverse effects.