title: A floating hydrogel system capable of generating CO2 bubbles to diminish urinary obstruction after intravesical instillation.
abstract: OBJECTIVE
  Intravesical instillation is commonly used to decrease the tumor recurrence after transurethral resection. However, most drug solutions would be eliminated from bladder after the first voiding of urine, so its clinical efficacy is limited. To overcome this obstacle, we developed a floating hydrogel system for controlled delivery of antitumor drugs.
  
  
  METHODS
  The floating hydrogel was made of Adriamycin, thermo-sensitive polymer (Poloxamer 407) and NH4HCO3, which was liquid at low temperature while forming hydrogel at high temperature. Meanwhile, at high temperature, NH4HCO3 decomposed to produce CO2 bubbles, which helped hydrogel float in bladder without urinary obstruction.
  
  
  RESULTS
  The mixture containing 45% P407 and 6% NH4HCO3 was selected as the optimal formulation. At 37°C, the mixture formed hydrogel and produced many bubbles which could be observed by B ultrasound. The vitro study showed that the antitumor drug Doxorubicin was released in a controlled manner. After the mixture was instilled into rabbit bladder, it formed hydrogel and floated in the bladder. The bladder stimuli was reduced and antitumor drugs could be released continuously in the bladder.
  
  
  CONCLUSIONS
  Our results suggested that the floating hydrogel was a feasible intravesical drug delivery system and may have application prospects in intravesical therapy for bladder cancer.
authors.affiliation: State Key Laboratory of Pharmaceutical Biotechnology, Nanjing University, 22 Hankou Road, Nanjing, 210093, China.
authors.forename: Tingsheng
authors.initials: T
authors.lastname: Lin
authors.forename: Yifan
authors.initials: Y
authors.lastname: Zhang
authors.forename: Jinhui
authors.initials: J
authors.lastname: Wu
authors.forename: Xiaozhi
authors.initials: X
authors.lastname: Zhao
authors.forename: Huibo
authors.initials: H
authors.lastname: Lian
authors.forename: Wei
authors.initials: W
authors.lastname: Wang
authors.forename: Hongqian
authors.initials: H
authors.lastname: Guo
authors.forename: Yiqiao
authors.initials: Y
authors.lastname: Hu
mesh_terms: D000283:Administration, Intravesical; D000818:Animals; D000903:Antibiotics, Antineoplastic / Q000008:administration & dosage* / Q000627:therapeutic use; D001639:Bicarbonates / Q000737:chemistry; D002245:Carbon Dioxide / Q000737:chemistry / Q000494:pharmacology*; D003692:Delayed-Action Preparations; D004317:Doxorubicin / Q000008:administration & dosage* / Q000627:therapeutic use; D004337:Drug Carriers / Q000737:chemistry*; D004339:Drug Compounding; D065546:Drug Liberation; D020100:Hydrogels; D007322:Instillation, Drug; D009364:Neoplasm Recurrence, Local / Q000517:prevention & control; D020442:Poloxamer / Q000737:chemistry; D011817:Rabbits; D013499:Surface Properties; D013696:Temperature; D014524:Urethral Obstruction / Q000209:etiology / Q000517:prevention & control*; D001749:Urinary Bladder Neoplasms / Q000601:surgery; D014783:Viscosity
chemical_list: D000903:Antibiotics, Antineoplastic; D001639:Bicarbonates; D003692:Delayed-Action Preparations; D004337:Drug Carriers; D020100:Hydrogels; D020442:Poloxamer; D002245:Carbon Dioxide; C027043:ammonium bicarbonate; D004317:Doxorubicin
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