Randomized, Triple-Blind, Vehicle-Controlled Trial of Topical Dapsone Gel 7.5% in Patients With Acne Vulgaris

Randomized, Triple-Blind, Vehicle-Controlled Trial Evaluating Clinical Efficacy, Sebum, Erythema, Melanin and Quality-of-Life Outcomes of Topical Dapsone Gel 7.5% in Patients With Acne Vulgaris

The goal of this randomized, triple-blind, vehicle-controlled clinical trial is to evaluate whether topical 7.5% dapsone gel is effective for treating mild-to-moderate acne vulgaris in adults.

The main questions are:

• Does dapsone gel improve global acne severity compared with a matched vehicle gel?
• Does dapsone gel improve comedonal and papulopustular acne severity?
• Does dapsone gel reduce erythema and melanin indices measured with a Mexameter, and sebum index measured with a Sebumeter?
• Does treatment with dapsone gel improve patients' acne-related quality of life?

Researchers compared once-daily dapsone gel with a matched vehicle gel without the active ingredient.

Participants:

• Applied either dapsone gel or vehicle gel once daily for 8 weeks
• Attended clinic visits at baseline, week 4, week 8, and week 12
• Had acne severity assessed using the Global Acne Grading System and Plewig and Kligman comedonal and papulopustular stages
• Had erythema and melanin measured with a Mexameter, and sebum measured with a Sebumeter at predefined facial sites
• Completed an acne quality-of-life questionnaire at baseline and week 8
• Had standardized photographs taken at each visit

Treatment was continued for 8 weeks, followed by a 4-week treatment-free follow-up through week 12.

Study Overview

• Status: Completed
• Conditions: Acne Vulgaris
• Intervention / Treatment: Drug: Dapsone 7.5% gel; Drug: Vehicle gel

Detailed Description

This is a prospective, randomized, triple-blind, vehicle-controlled clinical trial designed to evaluate the clinical efficacy of topical 7.5% dapsone gel in adults with mild-to-moderate acne vulgaris. The study also investigates the effects of topical dapsone on skin biophysical parameters using standardized instruments: erythema and melanin indices measured with a Mexameter, and sebum index measured with a Sebumeter.

Two parallel arms were included: one group applied topical 7.5% dapsone gel once daily, and the other applied a matched vehicle gel identical in base, tube, and packaging but without the active ingredient. Randomization was performed using a pre-generated computer-based randomization sequence. Participants, dispensing investigators, outcome assessors, and data analysts were blinded to treatment allocation.

Participants attended clinic visits at baseline, week 4, week 8, and week 12. Treatment was applied for 8 weeks, followed by a 4-week treatment-free follow-up period through week 12. At each visit, standardized digital photographs were taken, and acne severity was assessed using the Global Acne Grading System (GAGS), lesion counts used to assign Plewig and Kligman comedonal and papulopustular stages, and standardized clinical evaluation. At each visit, Mexameter readings for erythema and melanin and Sebumeter readings for sebum were obtained at three predefined facial sites: right cheek, left cheek, and forehead. Triplicate measurements were obtained at each site after a standardized acclimatization period. The Turkish-validated Gupta Acne Quality of Life Scale was administered at baseline and week 8.

The primary objective was to determine whether topical 7.5% dapsone gel reduces inflammatory lesion burden compared with matched vehicle at week 8. Secondary evaluations included changes in Global Acne Grading System (GAGS) total score, comedonal acne stage, sebum index, erythema index, melanin index, acne-related quality of life, and local cutaneous adverse events. By combining standardized clinical assessments, patient-reported outcomes, and objective biophysical measurements, this trial aimed to evaluate the clinical and biophysical effects of topical 7.5% dapsone gel in acne vulgaris.

• Study Type: Interventional
• Enrollment (Actual): 100
• Phase: Phase 4

Contacts and Locations

Study Locations

• Turkey (Türkiye)
  • Istanbul, Turkey (Türkiye), 34000
    • Istanbul Training and Research Hospital

Participation Criteria

Eligibility Criteria

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

Description

Inclusion Criteria:

• Adults aged 18 to 50 years with a clinical diagnosis of mild-to-moderate acne vulgaris.
• No systemic or topical acne treatment within the past 1 month (30 days).
• Able and willing to provide written informed consent.

Exclusion Criteria:

• Pregnancy or breastfeeding.
• Systemic retinoid or systemic antibiotic use within the past 6 months.
• Active dermatologic or systemic disease that could interfere with study participation or outcome assessments.
• Known hypersensitivity to dapsone or any component of the study product.

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: Dapsone 7.5% Gel; Topical dapsone 7.5% gel applied once daily to the entire face for 8 weeks, followed by a 4-week treatment-free follow-up.	Drug: Dapsone 7.5% gel; Topical dapsone 7.5% gel applied once daily to the entire face for 8 weeks; route: topical. The study product was supplied in an identical-appearing tube to maintain masking. Participants were followed for 4 weeks after treatment discontinuation.; Other Names: topical dapsone 7.5% gel; Vulgarex (country-specific brand)
Placebo Comparator: Vehicle Gel; Vehicle gel without dapsone, identical in base, tube, and packaging to the active product; applied once daily to the entire face for 8 weeks, followed by a 4-week treatment-free follow-up.	Drug: Vehicle gel; Vehicle gel without dapsone, identical in base, tube, and packaging to the active product; applied once daily to the entire face for 8 weeks; route: topical. Participants were followed for 4 weeks after treatment discontinuation.; Other Names: placebo gel

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change in Inflammatory Lesion Count (Papules/Pustules)	Mean change from baseline in the number of inflammatory facial acne lesions (papules and pustules) per Plewig & Kligman. Blinded dermatologist, standardized facial mapping. Between-group comparison: topical 7.5% dapsone gel vs vehicle/placebo gel.	Baseline to Week 8 (with interim assessment at Week 4)

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change in Global Acne Grading System (GAGS) Total Score	Change from baseline in Global Acne Grading System (GAGS; Doshi et al.) total score. Higher scores indicate more severe acne; a decrease reflects improvement. Between-group comparisons were performed at the end of treatment (week 8) and after the 4-week treatment-free follow-up (week 12).	Baseline to Week 12, with interim assessments at Week 4 and Week 8
Change in Plewig and Kligman Comedonal Acne Stage	Change from baseline in comedonal acne stage assigned according to Plewig and Kligman grading. Lower stages indicate less severe comedonal acne; a decrease reflects improvement. Between-group comparisons were performed at the end of treatment (week 8) and after the 4-week treatment-free follow-up (week 12).	Baseline to Week 12, with interim assessments at Week 4 and Week 8
Change in Erythema Index (Mexameter)	Change from baseline in facial erythema index measured with a Mexameter at three predefined facial sites: right cheek, left cheek, and forehead. Triplicate readings were obtained at each site after a standardized acclimatization period and averaged per visit. Between-group comparisons were performed at the end of treatment (week 8) and after the 4-week treatment-free follow-up (week 12).	Baseline to Week 12, with interim assessments at Week 4 and Week 8
Change in Melanin Index (Mexameter)	Change from baseline in facial melanin index measured with a Mexameter at three predefined facial sites: right cheek, left cheek, and forehead. Triplicate readings were obtained at each site after a standardized acclimatization period and averaged per visit. Between-group comparisons were performed at the end of treatment (week 8) and after the 4-week treatment-free follow-up (week 12).	Baseline to Week 12, with interim assessments at Week 4 and Week 8
Change in Sebum Index (Sebumeter)	Change from baseline in facial sebum index measured with a Sebumeter at three predefined facial sites: right cheek, left cheek, and forehead. Triplicate readings were obtained at each site and averaged per visit. Between-group comparisons were performed at the end of treatment (week 8) and after the 4-week treatment-free follow-up (week 12).	Baseline to Week 12, with interim assessments at Week 4 and Week 8
Change in Acne Quality of Life Scale (AQOL) Score	Change from baseline in Turkish-validated Acne Quality of Life Scale (AQOL) score (Gupta et al). Lower scores indicate better quality of life; a decrease reflects improvement. Between-group comparison.	Baseline to Week 8
Incidence and Severity of Local Cutaneous Adverse Events	Number and proportion of participants with treatment-emergent local cutaneous adverse events, including erythema, desquamation, scaling, burning, and tingling, graded for severity and relatedness.	Baseline to Week 12, with interim assessments at Week 4 and Week 8

Collaborators and Investigators

• Sponsor: Oya Helin Dundar
• Collaborators: Istanbul Training and Research Hospital
• Investigators: Principal Investigator: Oya Helin Dundar, MD, Istanbul Training and Research Hospital, Dept. of Dermatology; Study Director: Vildan Manav, MD, Assoc. Prof., Istanbul Training and Research Hospital, Dept. of Dermatology; Study Chair: Ayse Esra Koku Aksu, MD, Prof., Istanbul Training and Research Hospital, Dept. of Dermatology

Study record dates

Study Major Dates

• Study Start (Actual): June 17, 2025
• Primary Completion (Actual): February 1, 2026
• Study Completion (Actual): March 1, 2026

Study Registration Dates

• First Submitted: September 10, 2025
• First Submitted That Met QC Criteria: November 21, 2025
• First Posted (Actual): November 24, 2025

Study Record Updates

• Last Update Posted (Actual): May 22, 2026
• Last Update Submitted That Met QC Criteria: May 19, 2026
• Last Verified: May 1, 2026

More Information

Terms related to this study

• Keywords: Erythema; Melanin; Sebum; Dapsone gel; Topical dapsone 7.5%; Vehicle gel; Mexameter; Sebumeter; Global Acne Grading System (GAGS); Acne Lesion Count; Papulopustular acne; Comedonal acne; Acne Quality of Life Scale (AQOL)
• Additional Relevant MeSH Terms: Skin Manifestations; Skin Diseases; Acneiform Eruptions; Sebaceous Gland Diseases; Pathological Conditions, Signs and Symptoms; Skin and Connective Tissue Diseases; Signs and Symptoms; Acne Vulgaris; Erythema; Sulfur Compounds; Organic Chemicals; Pharmaceutical Preparations; Dosage Forms; Complex Mixtures; Sulfones; Colloids; Dapsone; Gels
• Other Study ID Numbers: SBU-IEAH-AV-DAP7P5-RCT-EC210; Medipol-EC-210 (Other Identifier: Istanbul Medipol Univ. Non-Interventional Clin. Research EC)

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No