Efficacy and safety of a novel weekly topical metformin-loaded peel-off mask in the treatment of melasma: a split-face, placebo-controlled study.

Background: Melasma is a common condition that affects a patient's quality of life. Metformin is a cheap, well-tolerated and relatively safe medication that is widely prescribed for the treatment of diabetes. Topical metformin has shown promising results in treating melasma as well as several other dermatological conditions such as acne and recalcitrant central centrifugal cicatricial alopecia.

Objectives: To study the efficacy and safety of a once-weekly topical metformin-30%-loaded peel-off mask for treating melasma.

Methods: Twenty female patients with melasma were recruited for the application of a metformin mask and placebo mask to either side of the face once weekly for 12 weeks. The hemi-Melasma Area Severity Index (hemi-MASI) was calculated at baseline, at each visit and 12 weeks after the end of treatment.

Results: At baseline, the hemi-MASI score matched between both metformin and placebo sides [7.1 (SD 2.6) and 7.1 (SD 2.6), respectively, P = 0.99]. At the end of the active treatment period, the metformin side showed a significantly better improvement in hemi-MASI score in comparison with placebo [68% (SD 0.2%) improvement on the metformin side in contrast to 20% (SD 0.2%) on the placebo side]. Although scores decreased 3 months after stopping the active treatment [52% (SD 0.2%) improvement on the metformin side compared with the placebo side 15% (SD 0.2%)], they were still significantly better than baseline. No adverse effects were reported.

Conclusions: Topical metformin-loaded peel-off masks can be a promising, safe and effective treatment for melasma. Although applied only once weekly, metformin peel-off masks show comparable efficacy to previously reported daily usage formulations.