Randomised controlled trial shows that glyceryl trinitrate heals anal fissures, higher doses are not more effective, and there is a high recurrence rate.

BACKGROUND Topical application of glyceryl trinitrate (GTN) ointment heals chronic anal fissures, providing an alternative to the traditional first line treatment of surgical sphincterotomy. AIMS To determine the most effective dose of topical GTN for treatment of chronic anal fissures and to assess long term results. METHODS Seventy consecutive patients with chronic anal fissure, were randomly allocated to eight weeks treatment with placebo, 0.2% GTN three times daily, or GTN starting at 0.2% with weekly 0.1% increments to a maximum of 0.6%, in a double blind study. RESULTS After eight weeks fissure had healed in 67% of patients treated with GTN compared with 32% with placebo (p=0.008). No significant difference was seen between the two active treatments. Headaches were reported by 72% of patients on GTN compared with 27% on placebo (p<0.001). Maximum anal sphincter pressure reduced significantly from baseline by GTN treatment (p=0.02), but not placebo (p=0.8). Mean pain scores were lower after treatment with GTN compared with placebo (NS). Of fissures healed with placebo 43% recurred, compared with 33% of those healed with 0.2% GTN and 25% healed with escalating dose GTN (p=0.7). CONCLUSIONS GTN is a good first line treatment for two thirds of patients with anal fissure. An escalating dose of GTN does not result in earlier healing. Significant recurrence of symptomatic fissures and a high incidence of headaches are limitations of the treatment.