Long-term results of "chemical sphincterotomy" for chronic anal fissure: a prospective study.

Introduction: Pharmacologic anal sphincter relaxants promote fissure healing; however, their effect is transient and the risk of late recurrence remains uncertain.

Methods: From August 1997 to August 2002, patients with chronic anal fissure attending our outpatient clinic were treated with a protocol that included: topical isosorbide dinitrate, 2.5 mg, or nifedipine, 0.