A double-blind randomized placebo-controlled trial of oral indoramin to treat chronic anal fissure

Abstract

Background: Indoramin is an alpha1-adrenoceptor antagonist and has been shown to reduce anal resting pressure. Its therapeutic potential has not been explored. The aim of this study was to determine the outcome of treatment with oral indoramin on patients with chronic anal fissure in the setting of a double-blind randomized placebo-controlled trial.

Methods: Twenty-three patients with chronic anal fissure were computer randomized to receive a 6-week course of oral indoramin (20 mg) or placebo in identical capsules, twice daily and with bulk-forming laxatives. Pain was assessed by a visual analogue scale from 0 to 10. Anal resting pressure, heart rate and blood pressure were recorded. Patients were reviewed 1 h after taking the capsule and at 2, 6 and 12 weeks thereafter.

Results: Fourteen patients were randomized to indoramin and 9 to placebo. Maximum anal resting pressure was reduced from a mean of 96.4 cm H2O (+/- 32) to 67.6 cm H2O (+/- 26), 1 h after indoramin (P=0.02) and there was no significant change after placebo. There were no significant changes in heart rate or blood pressure. Pain was reduced in the placebo group from a score of 4.9 to 2.0 after 6 weeks (P < 0.01) but not in the indoramin group. After 6 weeks, healing had occurred in one (7%) patient in the indoramin group and in 2 (22%) in the placebo group (P > 0.1). After 3 months, the chronic anal fissure in the indoramin group had recurred. The trial was terminated early because of poor healing rates.

Conclusion: An oral dose of indoramin (20 mg) administered twice daily reduced anal resting pressure by 30% compared with pretreatment levels but was ineffective in healing chronic anal fissures.