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A double-blind randomized controlled trial on the efficacy and safety of metformin as an adjunct to lymecycline and topical adapalene plus benzoyl peroxide gel in the treatment of moderate to severe acne vulgaris

Niña A. Gabaton, MD, DPDSa; Arnelfa C. Paliza, MD, FPDSb; Eleanor L. Letran, MD, FPDSb



Acne vulgaris has multifactorial causes. Prolonged systemic antibiotics are often necessary because relapse of lesions occurs upon its discontinuation. Currently, antimicrobial resistance is a growing concern. Androgen inhibitors like metformin may decrease need for antibiotics and maintain adequate control of the disease.



To determine the efficacy and safety of metformin versus placebo as an adjunct to lymecycline and adapalene+benzoyl peroxide gel in the treatment of moderate to severe acne vulgaris



Patients with moderate to severe acne vulgaris received either metformin or placebo tablets, together with lymecycline and adapalene+benzoyl peroxide gel. Lymecycline was taken for six weeks. The rest were given for 18 weeks. Evaluation was done biweekly using the mean reduction rates of non-inflammatory, inflammatory and total lesion count, modified global severity score, subjective self-assessment score, Dermatology life quality index (DLQI) score, and cutaneous and systemic adverse events.



Forty patients were selected for the trial. Mean reduction rates of the non-inflammatory lesion counts of the two groups were comparable (p>0.05). Mean reduction rates of the inflammatory and total lesion count in the metformin group were higher than the placebo group (p<0.05). The mean modified global severity score of the metformin group was lower than the placebo group (p=0.034). Mean DLQI scores decreased in both groups (p<0.0001). Subjective self-assessment scores improved in both groups with comparable results. Cutaneous adverse events (erythema, pain, scaling, and dryness) were tolerable. Systemic adverse events (diarrhea, flatulence, headache, and epigastric pain) were self-limited.



Metformin is an effective and safe adjunct in the treatment of moderate to severe acne vulgaris.


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A double-blind randomized controlled trial on the efficacy and safety of metformin as an adjunct to lymecycline and topical adapalene plus benzoyl peroxide gel in the treatment of moderate to severe acne vulgaris