In situ floating hydrogel for intravesical delivery of adriamycin without blocking urinary tract.

Drug solution is commonly used in conventional intravesical instillation. However, most of them would be easily eliminated by voiding, which significantly limit their efficacy. Recent advances in intravesical drug delivery are to use hydrogels as drug reservoir to extend the drug residence time in bladder. However, because of the high viscosity of hydrogel, urinary obstruction is usually existed during the intravesical instillation. To overcome these, we developed a floating hydrogel for the delivery of Adriamycin (ADR). The floating hydrogel was made of ADR, thermosensitive polymer (Poloxamer 407) and NaHCO₃, which was liquid at low temperature, whereas formed gel at high temperature. In the presence of H⁺, NaHCO₃ decomposed and produced CO₂ that attached on the surface of hydrogel and helped the hydrogel float on the urine. Hence, the urinary tract will not be blocked. Meanwhile, the encapsulated ADR released in a controlled manner. These results suggest that the floating gel may have promising applications in intravesical therapy for bladder cancer.