Purpose: The aim of this study was to determine the optimal dose and dosing interval of nitroglycerin ointment to heal chronic anal fissures.
Method: A randomized, double-blind study of intra-anally applied nitroglycerin ointment (Anogesic) was conducted in 17 centers in 304 patients with chronic anal fissures. The patients were randomly assigned to one of eight treatment regimens (0.0, 0.1, 0.2, 0.4 percent nitroglycerin ointment applied twice or three times per day), for up to eight weeks. A dose-measuring device standardized the delivery of 374 mg ointment. Healing of fissures (complete reepithelialization) was assessed by physical examination using an observer unaware of treatment allocation. The subjects assessed pain intensity daily by completing a diary containing a visual analog scale for average pain intensity for the day, the worst pain intensity for the day, and pain intensity at the last defecation.
Results: There were no significant differences in fissure healing among any of the treatment groups; all groups, including placebo had a healing rate of approximately 50 percent. This rate of placebo response was inexplicably higher than previously reported in the literature. Treatment with 0.4 percent (1.5 mg) nitroglycerin ointment was associated with a significant (P < 0.0002) decrease in average pain intensity compared with vehicle as assessed by patients with a visual analog scale. The decreases were observed by Day 4 of treatment. At 8 weeks the magnitude of the difference between 0.4 percent nitroglycerin and control was a 21 percent reduction in average pain. Treatment was well tolerated, with only 3.29 percent of patients discontinuing treatment because of headache. Headaches were the primary adverse event and were dose related.
Conclusion: Nitroglycerin ointment did not alter healing but significantly and rapidly reduced the pain associated with chronic anal fissures.