Botulinum neurotoxin to treat chronic anal fissure: results of a randomized "Botox vs. Dysport" controlled trial.

BACKGROUND: Botulinum neurotoxin induces healing in patients with idiopathic fissure. The optimal dosage is not well established. AIM: To compare the efficacy and tolerability of two different formulations of type A botulinum neurotoxin, and to provide more evidence with regard to the choice of dosage regimens. METHODS: Symptomatic adults with chronic anal fissure were enrolled in a randomized study. The outcome of each group was evaluated clinically, and by comparing the pressure of the anal sphincters before and after treatment. RESULTS: Fifty patients received injections of 50 units of Botox formulation (group I), and 50 patients received injections of 150 units of Dysport toxin (group II). One month after injection, 11 patients in group I and eight in group II had mild incontinence of flatus. At the 2-month evaluation point, 46 patients in group I and 47 patients in group II had a healing scar. In group I patients, the mean resting anal pressure was 41.8% lower, and the maximum voluntary squeeze pressure was 20.2% lower, than the baseline value. In group II patients, the resting anal pressure and maximum voluntary squeeze pressure were 60.0 +/- 12.0 mmHg and 71.0 +/- 30.0 mmHg, respectively. There were no relapses during an average of about 21 months of follow-up. CONCLUSIONS: Botulinum neurotoxin may be considered an effective treatment in patients with chronic anal fissure. The efficacy and tolerability of the two different formulations of botulinum neurotoxin were indistinguishable.