Short- and long-term effect of glyceryl trinitrate (GTN) ointment 0.2% and2% on anal canal pressure in patients with chronic anal fissures

Controversial data are available on the duration of action of glyceryl trin itrate 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 cana l pressure before and after eight weeks of treatment. Anal canal pressure w as evaluated in 12 patients with chronic anal fissures with an electronic p robe with three recording sites before and after the application of glycery l trinitrate, 120 mg on the external anal verge. Six patients received glyc eryl trinitrate at 0.2% and six at 2%. Glyceryl trinitrate 0.2% and 2% equa lly reduce basal anal canal pressure in all three recording sites (P < 0.00 1) 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 trin itrate was unchanged. In conclusion, glyceryl trinitrate ointment at 0.2% a nd 2%, equally reduces anal canal pressure for 60 min and this effect is ke pt unchanged after eight weeks of application.