Glyceryl trinitrate for chronic anal fissure--healing or headache? Results of a multicenter, randomized, placebo-controled, double-blind trial.

Purpose: Internal anal sphincterotomy for treating chronic anal fissure can irreversibly damage anal continence. Reversible chemical sphincterotomy may be achieved by anal application of glyceryl trinitrate ointment (nitric oxide donor), which has been reported to heal the majority of patients with anal fissure by inducing sphincter relaxation and improving anodermal blood flow. This trial aimed to further clarify the role of glyceryl trinitrate in the treatment of chronic anal fissure.
Methods: A total of 132 consecutive patients from nine centers were randomly assigned to receive 0.2 percent glyceryl trinitrate ointment or placebo twice daily for at least four weeks. The severity of pain and maximum anal resting pressure were measured before and after one week of treatment. Anodermal blood flow was measured before and after application of glyceryl trinitrate or placebo in ten patients.
Results: The study was completed by 119 patients (59 glyceryl trinitrate and 60 placebo), matched for gender, age, duration of symptoms, duration of treatment, site of fissure, previous attempts to treat, pain score, and maximum anal resting pressure. Twenty-nine patients (49.2 percent) healed after glyceryl trinitrate and 31 patients (51.7 percent) healed after placebo (P = not significant). Pain score fell significantly in both groups, in addition to maximum anal resting pressure. Anodermal blood flow improved significantly in seven patients receiving glyceryl trinitrate, but not in the three receiving placebo. Twenty-three patients (33.8 percent) experienced headache and 4 (5.9 percent), orthostatic hypotension after glyceryl trinitrate.
Conclusion: This trial fails to demonstrate any superiority of topical 0.2 percent glyceryl trinitrate treatment vs. a placebo, although the effects of glyceryl trinitrate on anodermal blood flow and sphincter pressure are confirmed. This finding, together with the high incidence of side-effects, should discourage the use of this treatment as a substitute for surgery in chronic anal fissure.