Table 2.

Changes in colorimetric values (L∗, a∗), MASI index, and Mean Fluorescence Intensity (MFI) in melasma lesions treated with 4% niacinamide, 0.05% retinoic acid, and placebo; initially and at the end of the study.

	Initial values				Values after 8 weeks of treatment
	4% Niacinamide (n=10)	0.05% Retinoic acid (n=10)	Placebo (n=10)	P value	4% Niacinamide (n=10)	0.05% Retinoic acid (n=10)	Placebo (n=10)	P value
L∗	46.5 ± 3.8	47.2 ± 3.2	47.7 ± 3.8	0.16	52.7 ± 2.3∗∗	50.2 ± 3.1	48.4 ± 4.2	0.01
a∗	11.7 ± 1.8	12.1 ± 0.5	12.7 ± 0.9	0.1	11.4 ± 1.2	12.3 ± 1.8	12.6 ± 2.5	0.06
MASI	15.4 ± 6.7	18.5± 13.5	9.1± 1.4	0.1	10.4 ± 5.1	12.9 ± 6.4	7.1 ± 1.2∗∗	0.03
MFI	70 ± 5	74 ± 2	68 ± 3	0.4	50 ± 3	53 ± 5	64 ± 2∗∗	<0.01

L∗: axis values; a∗: erythema axis values; p values obtained by t test. The groups did not differ in colorimetric, MASI, and MFI values at onset (ANOVA, P >0.05).