Pathophysiological aspects and clinical outcome of intra-anal application of isosorbide dinitrate in patients with chronic anal fissure

Abstract

Background: Relaxation of the internal anal sphincter can be achieved by local application of exogenous nitric oxide donors.

Aim: To evaluate the influence of topical application of isosorbide dinitrate (ISDN) on anal pressure, anodermal blood flow, and fissure healing.

Patients: Thirty four consecutive patients (male/female: 18/16; mean age (SEM): 39 (10)) with a chronic anal fissure were studied.

Methods: All patients were treated for at least six weeks or a maximum period of 12 weeks. Before treatment and at three and six weeks 22 patients underwent conventional anal manometry and laser Doppler flowmetry of the anoderm.

Results: Within 10 days the fissure related pain was resolved in all patients. At six, nine, and 12 weeks the anal fissure was completely healed in 14, 22, and 30 patients respectively. At three and six weeks manometry was performed at least one hour after the last application of ISDN. These recordings showed a reduction of the maximum resting anal pressure (mean (SD), pretreatment 111 (26) mm Hg; three weeks 86 (19); six weeks 96 (27), p < 0.001). Simultaneous recordings of anodermal blood flow showed a significant increase of flow (pretreatment 0.53 (0.17); three weeks 0.80 (0.16); six weeks 0.76 (0.31), p < 0.005). The mean (SEM) duration of follow up after successful outcome was 11 (5) months. Within this period fissure relapsed in two of 30 patients (7%), eight and 10 weeks after treatment had been stopped.

Conclusions: Local application of ISDN reduces anal pressure and improves anodermal blood flow. This dual effect results in a fissure healing rate of 88% at 12 weeks. This new and simple treatment modality seems to be an attractive alternative for the current available surgical procedures.