Alpha-1 adrenoceptor blockade - Potential new treatment for anal fissures

PURPOSE: Patients with chronic anal fissures are known to have high resting anal pressures that return to normal after successful surgical treatment. Internal anal sphincter activity is increased by sympathetic excitatory inn ervation via alpha adrenoceptors. The objective of this study was to determ ine the effect of alpha-1 adrenoceptor blockade on anal sphincter pressure in patients with and without chronic anal fissures. METHODS: The effect on the anal canal pressure profile of a single oral 20 mg dose of indoramin, a n alpha-1 adrenoceptor antagonist, on seven patients with chronic anal fiss ure and six healthy patients without a fissure was investigated. RESULTS: I ndoramin reduced anal resting pressures in those with anal fissure by a mea n of 35.8 percent, from 106.9 +/- 22.15 cm H2O to 68.6 +/- 20.35 cm H2O, an d in those without anal fissure by a mean of 39.9 percent, from 84.17 +/- 2 7.46 cm H2O to 52.17 +/- 24.78 cm H2O, after one hour. This pressure reduct ion persisted at three hours, and its magnitude is comparable to that obtai ned after internal sphincterotomy. The pressure reduction occurred over the whole length of the anal canal. CONCLUSION: It is proposed that alpha-1 ad renoceptor antagonists could be a suitable treatment for chronic anal fissu re and other painful conditions where reduction in anal pressure is warrant ed.