Low Versus High Dose OnabotulinumtoxinA for Chronic Anal Fissure

Low Versus High Dose OnabotulinumtoxinA for Chronic Anal Fissure: A Randomized Clinical Trial With 1-Year Follow-up

The goal of this clinical trial is to evaluate the efficacy of botulinum toxin injection in treatment of patients with chronic anal fissures comparing between two doses of botulinum toxin injection focusing on healing rate, fissure pain, incontinence and return to daily activity. patients will be divided into two groups group A) will receive 50IU from Botulinium toxin type A in the form of two injections at 3 o'clock and 9 o'clock without any anasthesia. While group B) will receive low dose injection in the form of 20IU by the same technique.

Study Overview

• Status: Completed
• Conditions: Chronic Anal Fissure
• Intervention / Treatment: Drug: injection of Botulinum type A

Detailed Description

Background: Severe anal pain and a lower quality of life are two consequences of chronic anal fissure (CAF). The ideal dosage for botulinum toxin type A (BoNT-A), a sphincter-preserving substitute for lateral internal sphincterotomy, is still unknown. In this study, fixed-site 20 U and 50 U onabotulinumtoxinA regimens were compared using a structured 1-year follow-up and a standard injection technique at 3 and 9 o'clock.

Aim of the study:The aim of the work is to evaluate the efficacy of botulinum toxin injection in treatment of patients with chronic anal fissures comparing between two doses of botulinum toxin injection focusing on healing rate, fissure pain, incontinence and return to daily activity Methods: OnabotulinumtoxinA 20 U (10 U per site) or 50 U (25 U per site) were randomly assigned to 70 adults with CAF who were refractory to at least 8 weeks of medical therapy in this prospective, randomized, double-blind, parallel-group trial. At eight weeks, complete clinical fissure healing was the main result. Pain and bleeding response, healing time, recurrence following initial healing, temporary flatus incontinence, and the need for surgery during a one-year follow-up were secondary outcomes. Recurrent and persistent non-healing cases went straight to surgery instead of another injection.

• Study Type: Interventional
• Enrollment (Actual): 70
• Phase: Phase 3

Contacts and Locations

Study Locations

• Egypt
  • Tanta, Egypt
    • Faculty of Medicine Tanta University

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

• Participants were required to have persistent symptoms despite standard first-line management.

Exclusion Criteria:

Exclusion criteria included atypical fissure location or appearance, such as lateral or multiple fissures; suspected secondary causes, including Crohn's disease, infection, tuberculosis, HIV-related ulceration, or malignancy; the presence of a perianal fistula or abscess; and contraindications or high-risk conditions for botulinum toxin treatment, including pregnancy, breastfeeding, known hypersensitivity to botulinum toxin products, active infection at the injection site, or significant neuromuscular junction disorders.

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Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: Triple

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Arm 1 Low Dose Group; Patients recieve injection of a low dose 20 IU of botulinum toxin for treatment of chronic anal fissure	Drug: injection of Botulinum type A; injection of low dose 20 IU of Botoulinum toxin type A to arm 1 and high dose 50 IU to arm 2
Experimental: Arm2 : High Dose group; Patients recieve injection of a high dose 50 IU of botulinum toxin for treatment of chronic anal fissure	Drug: injection of Botulinum type A; injection of low dose 20 IU of Botoulinum toxin type A to arm 1 and high dose 50 IU to arm 2

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
pain reduction measured by visual analogue scale	change in pain score from baseline to follow up visits after botulinum toxin injection	4 weeks

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Fissure complete healing	complete healing of chronic anal fissure as assessed by clinical examination	4-8 weeks

Collaborators and Investigators

• Sponsor: Tanta University

Study record dates

Study Major Dates

• Study Start (Actual): August 1, 2023
• Primary Completion (Actual): August 30, 2025
• Study Completion (Actual): December 30, 2025

Study Registration Dates

• First Submitted: April 14, 2026
• First Submitted That Met QC Criteria: April 14, 2026
• First Posted (Actual): April 21, 2026

Study Record Updates

• Last Update Posted (Actual): April 21, 2026
• Last Update Submitted That Met QC Criteria: April 14, 2026
• Last Verified: April 1, 2026

More Information

Terms related to this study

• Other Study ID Numbers: 36264PR284/7/23

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: Yes
• Studies a U.S. FDA-regulated device product: No
• product manufactured in and exported from the U.S.: Yes