title: Urodynamic effects of intravesical oxybutynin chloride in conscious rats.
abstract: OBJECTIVE
  To examine the factors of intravesical oxybutynin influencing the cystometrogram in normal conscious rats at various pH levels and concentrations of oxybutynin.
  
  
  METHODS
  A cystostomy catheter was implanted into the bladders of male Sprague-Dawley rats. We compared the urodynamic effects of intravesical oxybutynin dissolved in pH 4.44, 6.44 and 8.44 buffer. Two concentrations of oxybutynin solution were adopted, 0.06 and 0.6 mg./ml., and were dissolved in each pH buffer.
  
  
  RESULTS
  Although a 26% increase in bladder capacity was recognized 1 hour after instillation of pH 8.44, 0.06 mg./ml. oxybutynin, no significant difference was found in comparison with control rats. At the concentration of 0.6 mg./ml., bladder capacity markedly decreased 30 minutes to 1 hour after instillation even at pH 6.44 and 8.44. Significant decreases in detrusor contraction pressure were recognized 30 minutes to 1 hour after instillation. However, there were no significant differences among the 3 pH oxybutynin solutions. Compared with preinstillation values, significant increases in residual urine rates were observed in all pH oxybutynin solutions. Furthermore, the residual urine rate after instillation of pH 8.44 oxybutynin solution differed significantly from that of pH 4.44 oxybutynin.
  
  
  CONCLUSIONS
  Our results demonstrate that pH and concentration of intravesical oxybutynin solution may play an important role in relaxation of the bladder. A high concentration of oxybutynin is considered irritating to the bladder mucosa.
authors.affiliation: Department of Urology, School of Medicine, Kanazawa University, Japan.
authors.forename: O
authors.initials: O
authors.lastname: Yokoyama
authors.forename: Y
authors.initials: Y
authors.lastname: Ishiura
authors.forename: Y
authors.initials: Y
authors.lastname: Nakamura
authors.forename: M
authors.initials: M
authors.lastname: Ohkawa
mesh_terms: D000283:Administration, Intravesical; D000818:Animals; D003243:Consciousness; D004305:Dose-Response Relationship, Drug; D008297:Male; D008333:Mandelic Acids / Q000494:pharmacology*; D010276:Parasympatholytics / Q000494:pharmacology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D001743:Urinary Bladder / Q000187:drug effects* / Q000502:physiology*; D014563:Urodynamics / Q000187:drug effects*
chemical_list: D008333:Mandelic Acids; D010276:Parasympatholytics; C005419:oxybutynin