Effect of 5-HT1 agonist (sumatriptan) on anorectal function in irritable bowel syndrome patients.

AIM

To evaluate the effect of sumatriptan, a selective 5-HT1 agonist, on anorectal function in irritable bowel syndrome (IBS) patients.

METHODS

Twenty-two IBS patients selected according to the Rome II criteria (F 15, M 7; mean age 29.3+/-6.8, range 22-44 years) were examined. The study was blind, randomized and placebo-controlled with a crossover design. Anorectal manometry and rectal balloon distension test were performed before and after the administration of placebo and sumatriptan.

RESULTS

The administration of sumatriptan caused a significant increase in the resting anal canal pressure from 9.2+/-2.0 kPa to 13.1+/-3.3 kPa (P<0.0001) connected with the increase in the anal sphincter length and high pressure zone. After sumatriptan injection a remarkable increase in the threshold for the first sensation from 27+/-9 mL to 34+/-12 mL (P<0.05) and urge sensation from 61+/-19 mL to 68+/-18 mL (P<0.01) was observed. Sumatriptan did not affect either the volume evoking the rectoanal inhibitory reflex or the results of the straining test.

CONCLUSION

5-HT1 receptors participate in the regulation of anorectal function. Elucidation of the role of 5-HT1 receptors in the pathophysiological mechanisms of IBS may have some therapeutic implications.