Short- and long-term effect of glyceryl trinitrate (GTN) ointment 0.2% and 2% on anal canal pressure in patients with chronic anal fissures.

Controversial data are available on the duration of action of glyceryl trinitrate after acute and chronic application on anal canal pressure. Our aim was to assess the effect of glyceryl trinitrate at 0.2% and 2% on anal canal pressure before and after eight weeks of treatment. Anal canal pressure was evaluated in 12 patients with chronic anal fissures with an electronic probe with three recording sites before and after the application of glyceryl trinitrate, 120 mg on the external anal verge. Six patients received glyceryl trinitrate at 0.2% and six at 2%. Glyceryl trinitrate 0.2% and 2% equally reduce basal anal canal pressure in all three recording sites (P < 0.001) with major effect on the inner site of the canal toward the rectum, for a 60-min period. Eight weeks after application, the effect of glyceryl trinitrate was unchanged. In conclusion, glyceryl trinitrate ointment at 0.2% and 2%, equally reduces anal canal pressure for 60 min and this effect is kept unchanged after eight weeks of application.