Isosorbide dinitrate ointment vs botulinum toxin A (Dysport) as the primary treatment for chronic anal fissure: a randomized multicentre study

Colorectal Dis. 2014 Oct;16(10):O360-6. doi: 10.1111/codi.12615.


Aim: Nitric oxide donors, such as isosorbide dinitrate ointment (ISDN), are considered as first-choice agents in the treatment of chronic anal fissure. Injection with botulinum toxin A in the internal anal sphincter is often used as a second-line therapy, although it may give better results and fewer side effects than nitric oxide donors. The aim of this randomized clinical trial was to investigate whether botulinum toxin A (Dysport) is more effective than ISDN in the primary treatment of chronic anal fissure.

Method: From April 2005 until October 2009, 60 patients (32 men) with a median age of 42 (25-82) years were randomized to receive either ISDN 10 mg/ml (1%) (n = 33) or injection with 60 units of Dysport (n = 27). The primary end-point was the percentage of complete fissure healing after 8 weeks.

Results: After a median of 9 weeks complete fissure healing was noted in 18 of 27 patients in the Dysport group and in 11 of 33 patients in the ISDN group (P = 0.010). Absolute improvement of pain scores after 9 weeks was similar in both groups (P = 0.733). Patients treated with Dysport had fewer side effects than patients treated with ISDN (P = 0.028). Of the patients with a healed fissure, 28% of the Dysport group and 50% of the ISDN group had a recurrence within 1 year (P = 0.286; hazard ratio 2.08; 95% CI = 0.54-7.97).

Conclusion: Dysport is more effective than ISDN ointment and has fewer side effects in the primary treatment of chronic anal fissure. The recurrence rate within 1 year in both treatment groups is high.

Keywords: Anal fissure; Dysport; ISDN; botulinum toxin A; isosorbide dinitrate ointment.

Publication types

  • Comparative Study
  • Multicenter Study
  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acetylcholine Release Inhibitors / therapeutic use*
  • Administration, Topical
  • Adult
  • Aged
  • Aged, 80 and over
  • Anal Canal
  • Botulinum Toxins, Type A / therapeutic use*
  • Chronic Disease
  • Female
  • Fissure in Ano / complications
  • Fissure in Ano / drug therapy*
  • Humans
  • Injections, Intramuscular
  • Isosorbide Dinitrate / therapeutic use*
  • Male
  • Middle Aged
  • Nitric Oxide Donors / therapeutic use*
  • Ointments
  • Pain / etiology
  • Recurrence


  • Acetylcholine Release Inhibitors
  • Nitric Oxide Donors
  • Ointments
  • Botulinum Toxins, Type A
  • abobotulinumtoxinA
  • Isosorbide Dinitrate