Topical metformin in the treatment of melasma: A preliminary clinical trial

Melasma is a common acquired pigmentary disorder characterized by symmetric hyperpigmented macules on the face. Triple combination cream (TCC) remains the gold standard treatment but its prolonged use often causes adverse effects. Recently, studies have shown that topical metformin has melanopenic action.

To evaluate the safety and efficacy of topical metformin in the treatment of melasma and to compare its efficacy with TCC (hydroquinone 2% + tretinoin 0.025% + fluocinolone acetonide 0.01%).

This was a randomized controlled study conducted on 40 patients with melasma aged more than 18 years. Patients in group 1 (n = 20) were treated with 30% metformin lotion, whereas group 2 patients (n = 20) were treated with TCC for 8 weeks. Pigmentation was assessed using Melasma Area and Severity Index (MASI) at baseline and after 8 weeks. Outcome measures included global improvement scale (grades 1-4) and patient satisfaction. Safety was assessed according to adverse events and patch testing.

All 40 patients completed the study. Out of 20 patients in group 1, 11 showed grade 1 improvement (1% to <25%) and grade 2 (25%-50%) and grade 3 (>50%-75%) improvements were seen in one patient each. In group 2, grades 1, 2, 3, and 4 improvements were seen in 14, 2, 1, and 1 patients, respectively. However, the difference was not statistically significant. Adverse events were noted in three patients in group 2 and none in group 1.

Topical metformin is a novel, safe, and almost as effective modality as TCC to treat melasma.