We found no systematic reviews. We found five RCTs. The first trial was an open RCT (50 Oriental people, 49 women, with non-dermal melasma and not taking oral contraceptives).18 It compared the daily use of a cream containing 20% azelaic acid, 0-05% tretinoin and sunscreen, with a cream containing 20% azelaic acid and sunscreen, for a period of 6 months with monthly evaluations. The number of withdrawals was high and therefore it is difficult to draw conclusions. Furthermore, some outcome categories overlapped.
A second RCT29 (65 dark-skinned people, skin phototypes >III, with hyperpigmentation, 44 (68%) of whom had melasma) compared a cream containing 20% azelaic acid cream plus 15-20% glycolic acid (first month only) plus sunscreen with 4% hydroquinone plus sunscreen; participants were followed for 24 weeks. There was no difference between the two groups in overall improvement, and reduction in lesion area, pigmentary intensity and disease severity were comparable in the two treatment groups.
A third RCT30 in 40 Chinese women with pure epidermal melasma confirmed by Wood's lamp (age range not specified) compared the twice-daily application of a gel containing 2% kojic acid, 2% hydroquinone and 10% glycolic acid followed by a sunblock with titanium dioxide SPF15 with the twice-daily application of a control gel containing 2% hydroquinone and 10% glycolic acid, followed by sunblock with titanium dioxide SPF15. Randomisation was used to determine which side of the face would receive each intervention. Data from three women who withdrew were not included in the analysis. The frequency of >50% clearance of the melasma area was higher where kojic acid was used, although this difference was not significant (24/40 (60%) for the combined gel containing kojic acid versus 19/40 (48%) for the combined gel without kojic acid; RR 1-3, CI 0-8-1-9). When participating women assessed improvement, this was found to be better with the gel containing kojic acid.
The fourth RCT31 included 38 non-childbearing women with skin phototype I—IV and melasma (type not specified). The study randomised affected areas of skin instead of people and was achieved using a list. The study compared a cream containing 12% alpha hydroxyacid (particular preparation not specified), 1% polypeptide ascorbate complex and titanium oxide photoprotector with a preparation containing titanium oxide photoprotector and the vehicle for the cream prepared to the same pH. It found that patient global assessment, which was measured using a visual analogue scale for area and pigmentation, improved in more women receiving active treatment than in those using the placebo preparation. However this difference did not quite reach significance (34/36 (94%) with the combination treatment versus 17/36 (47%) with placebo. RR 1-51, CI 0-96-2-40). Differences were significant for the melanic index measured using a Mexameter (mean melanic index 15-2 with active treatment versus 22-1 with placebo; P<0-01 at day 56).
The fifth RCT32 (39 people with facial melasma, 5% of them with dermal melasma under Wood's light; 38 women, followed for 3 months) compared 2% hydroquinone and 5% glycolic acid gel with 2% kojic acid and 5% glycolic acid gel. This study compared interventions applied to the left or right side of the face. Outcomes were comparison of facial photographs taken using an ultraviolet filter, clinical evaluation, participants' impressions and decrease in affected area (no formal scales were used). There were no significant differences between groups (28% reduction with kojic acid and 21% reduction with hydroquinone).
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