A Double Blind Randomized Trial of Efficacy and Safety of 5% Methimazole Versus 2% Hydroquinone in Patients with Melasma

Melasma is an acquired facial hyperpigmentation that is chronic and resistant to treatment. This study aimed at comparing the therapeutic response and safety of 5% methimazole cream versus 2% hydroquinone cream in Iranian females with melasma.

This was a randomized, controlled, double-blind clinical trial. Fifty-eight patients aged 18 to 50, and who had been clinically diagnosed with melasma were enrolled. They were randomly divided to 2 groups: those treated with 5% methimazole cream and those treated with 2% hydroquinone once nightly for 8 weeks. Their responses to treatment were evaluated using the Melasma area and severity index (MASI), the ΔE score obtained using VisioFace digital photography, and the patients’ own satisfaction. Safety was assessed by measuring thyroid-stimulating hormone (TSH) levels. For statistical analysis, the SPSS version 16.0 for Windows (SPSS Inc., Chicago, IL) was used.

The subjective assessments of methimazole and hydroquinone (patient satisfaction) were as follows: excellent and good, 67.7% for methimazole vs. 70.3% for hydroquinone, and moderate and mild, 32.2% for methimazole versus 29.6% for hydroquinone. The assessments showed no statistical differences between the 2 groups (P = 0.942). At the end of treatment, MASI scores were significantly lower in the methimazole group than in the hydroquinone group (P = 0.042). The VisioFaceΔE scores were also significantly lower in the methimazole group than in the hydroquinone group (P = 0.049). Serum thyroid stimulating hormone (TSH) levels showed no statistical differences between the 2 groups (P = 0.613).

Compared with 2% hydroquinone, topical methimazole was more effective for improving melasma and had no effect on serum TSH levels. Therefore, methimazole could be considered as a first-line or combination therapy for melasma.