Efficacy of local metronidazole with glyceryl trinitrate versus topical glyceryl trinitrate alone in the treatment of acute anal fissure: a randomized clinical trial

Introduction
Anal fissure is one of the most common diseases of the anorectal region that is frequently encountered in surgical practice, equally affects both women and men. Acute anal fissures last shorter than 6 weeks. The American Society of Colon and Rectal Surgeons favors conservative management of anal fissure as the first line of treatment. A rectal ointment containing 0.2% glyceryl triturate (GTN) can be recommended to promote the healing of anal fissures and decreasing sphincter spasm. Metronidazole is a 5-nitroimidazole derivative antibiotic with a cytotoxic bactericidal effect particularly on anaerobic bacteria. The purpose of the present study was to investigate whether local metronidazole antibiotic cream is effective and safe to use in reducing the symptoms and improving the healing process of acute anal fissure.
Patients and methods
This study was performed in Mansoura University Hospital, surgery outpatient clinic from the period of July 2022 till July 2023. This study was a single-blinded, randomized controlled trial. Total 100 patients were included in this study and randomly divided into two groups, 50 patients in each group. First group (group 1) treated by combination of local metronidazole 10% with 0.2% GTN while the second group treated only with GTN.
Results
Anal pain were present in both group in all patients with acute anal fissure while constipation were 88% in group 1 and 76% group 2. To lesser extent itching, bleeding, and diarrhea were presented in both group. Visual analog scale for pain intensity were equal in both groups at the time of first clinical examination. After 1 week and 1 month of treatment there were statistically significant difference between both groups thus the visual analog scale were lower in group 1 than group 2 (0.001 and <0.001, respectively). Healing of acute anal fissure was assessed clinically at variable interval for all patients there is statistically significant difference between both group (0.004) as regard healing, first group showed earlier and faster healing and fewer number of nonhealing of the fissure at the end of follow up.
Conclusion
Adding local metronidazole 10% to the classic GTN treatment will improve the symptoms of acute anal fissure specially pain and discomfort and markedly accelerate healing process.