RESUMO
BACKGROUND: Anal fissure is a common anorectal problem causing severe pain and discomfort to the patients. Chemical sphincterotomy has emerged as a noninvasive alternative to the surgical methods of fissure treatment. The objective of this study was evaluation of the efficacy and the adverse effects of topically applied minoxidil in chemical sphincterotomy of chronic anal fissure in comparison with topical diltiazem. METHODS: A total of 88 patients with chronic anal fissure aged between 15 and 65 years were included in this double-blind, randomized clinical trial and were randomly assigned to either 0.5% minoxidil cream or 2% diltiazem cream twice daily for 2 weeks. The pain intensity, bleeding, wound healing, itching, headache, dizziness, significant drop in blood pressure, allergy and fissure relapse were assessed on a monthly basis for 2 months. RESULTS: Both diltiazem and minoxidil reduced the pain, bleeding and improved fissure healing with no significant difference. There were no between-groups differences in the frequencies of adverse effects, except for itching which was slightly higher with minoxidil during the first month. Allergy occurred in two patients in the minoxidil group, which was not severe and did not lead to discontinuation of the trial. CONCLUSION: Topically administered minoxidil is of equal efficacy as diltiazem in the treatment of chronic anal fissure with low frequency of adverse effects. Thus, it can be considered as an agent for chemical sphincterotomy of anal fissure, but the itching at the beginning of the treatment can affect the adherence of the patient to treatment. Trial registration number IRCT2015041414483N6 (the full trial protocol could be accessed online at www.irct.ir ).