Manometric effect of topical glyceryl trinitrate and its impact on chronic anal fissure healing

INTRODUCTION: The duration of physiologic action of topical glyceryl trinitrate in the management of anal fissure has been the source of some controversy. This study was designed to assess the manometric effect of glyceryl trinitrate on internal sphincter resting tone with continuous monitoring. METHODS: Twenty-seven patients with a chronic anal fissure were assessed with fissure, pain, bleeding, and continence scores. Twenty-two were randomized to 1 cm of topical 0.2 percent glyceryl trinitrate paste, applied to the lower anal canal. Five patients were randomized to I cm of water-soluble lubricating jelly to the lower anal canal. Continuous stationary six radial channel water perfusion anorectal manometry was performed for 5 minutes before treatment and then for a further 30 minutes. The 22 glyceryl trinitrate patients were then advised to apply topical 0.2 percent glyceryl trinitrate, three times daily, for eight weeks. Twenty-four hours after completing treatment, all baseline assessments were repeated. The lubricant jelly cohort was discharged from the study after the initial assessment. RESULTS: During the initial manometric assessment, 21 glyceryl trinitrate patients (95 percent) had 20 percent or more reduction in mean and maximum anal resting pressure after treatment. However, there was no statistical difference at 20 minutes compared with 0 minutes (P > 0. 1). After eight-week treatment, 16 patients (73 percent) reported symptom resolution and 15 (67 percent) were found to be healed on examination. Clinical healing and resolution of symptoms positively correlated with a higher pretreatment maximum anal resting pressure in the mid anal canal (P < 0.0001), lower fissure score (P < 0.0001), and greater percentage reduction of the maximum resting pressure after application of glyceryl trinitrate (P < 0.001). The mean and maximum anal resting pressure at Week 8 was not significantly different from the baseline values (P > 0.05). During continuous manometry, the anal resting pressure did not significantly change in the patients treated with lubricating jelly. CONCLUSIONS: In those patients with a lower fissure score, a higher mid anal canal anal resting pressure, and a greater resting pressure reduction after glyceryl trinitrate application, a favorable clinical outcome can be expected with glyceryl trinitrate treatment. However, because the physiologic response has resolved in fewer than 20 minutes, the dosing regime should be reassessed.