Effects of spasmolytic and/or non-steroidal antiinflammatory drugs on muscle hyperalgesia of ureteral origin in rats

Rats with artificial calculosis of one ureter develop hyperalgesia in the ipsilateral oblique musculature as evidenced by decreased vocalization threshold to electrical muscle stimulation lasting over a week. The aim of the study was to evaluate the effect on this hyperalgesia of spasmolytic anticholinergic and/or non-steroidal antiinflammatory drugs, common therapies for colic pain in humans. Rats implanted with a unilateral ureteral stone were treated for 10 days with: (1) saline; (2) hyoscine-N-butylbromide (15 mg/kg/day i.p.); (3) ketoprofen (15 mg/kg/day); or (4) hyoscine-N-butylbromide + ketoprofen (15 + 15 mg/kg/day). Oblique muscle vocalization thresholds were measured daily for 3 days before and 10 days after operation. Ipsilateral thresholds decreased significantly after stone implantation on: (1) seven days (max. 32%) for saline; (2) one day (max. 20%) for hyoscine-N-butylbromide; (3) one day (max. 18%) for ketoprofen, but did not change significantly for hyoscine-N-butylbromide + ketoprofen. These results indicate a protective effect against muscle hyperalgesia of ureteral origin by spasmolytic and antiinflammatory drugs, maximal when the two treatments are combined.