BACKGROUND: The oxybutynin is an anticholinergic agent that binds to muscarinic receptors of bladder muscle promoting an antispasmodic effect. As a consequence there is an increase in bladder capacity, reduction in frequency and a blockade in the initial stimuli of miction. OBJECTIVE: To verify the action of oxybutynin on bladder overactivity due to hemorrhagic cystitis. METHODS: Hemorrhagic cystitis was provoked through an intraperitoneal injection of 200mg/kg of cyclophosphamide in 10 female rats, weighting 200-250g, 24h before the experiment. The control group of 5 female rats received an intraperitoneal injection of 0.5ml of saline. In the experiment the animals were anesthetized with 1.25mg/kg of urethane followed by a cystostomy with a P-50 catheter connected in Y to an infusion pump (rate of infusion - 0.3ml/min) and to a polygraph to register bladder pressure. The parameters studied were: frequency of bladder contraction (Fc), contraction intensity (Ci), time of bladder filling (Tf) and contraction (Tc), and vesical capacity (Vc) (Tf x flow). We determined the mean value for each parameter following of 10min of observation. After these determinations all rats received 71mg/kg of oxybutynin chloride through nasogastric tubing and 1h afterward the measures were repeated. The data were compared with the Kruskal-Wallis test considering significant a p<0.05. RESULTS: A comparison both groups (control versus experimental) before the use of oxybutynin showed the following values of p: Fc - 0.007; Ci - 0.0002; Tf - 0.768; Tc - 0.492; Vc - 0.055. After the use of oxybutynin the corresponding values were: Fc - p=0.055; Ci - p=0.0002; Tf - 0.957; Tc - p=0.181; Vc - p=0.206. CONCLUSION: The oxybutynin chloride was able to control bladder overactivity expressed by a significant reduction in frequency, but no changes in other parameters.
Cystitis, frequency; Oxybutynin; Cyclophosphamide
