Comparison between baseline and posttreatment on melanin index measured by Mexameter (face, sun-exposed forearm, sun-protected arm) and VISIA™ CR system (UV spots, evenness, and pores) for each group as well as between groups.
Baseline vs posttreatment. (1) Melanin index in 6 areas decreased significantly in glutathione groups. On the contrary, in placebo arm, melanin index increased in facial area and decreased in the other areas. (2) No significant difference between baseline and post-treatment on VISIA analysis. There were significant increases for right and left UV spot in placebo arm ( and , respectively). Comparison between glutathione and placebo. Melanin index in glutathione arm decreased significantly compared to the control in all sun-exposed areas, especially right side of the face () and left forearm (). UV spot in glutathione arm increased slightly. However, increased skin smoothness and decreased pore size were also observed in this group. Compared to placebo, these findings were not significant.
Glutathione was significant in most of the sun-exposed areas.
Changes in skin color were observed after 12 injections of glutathione as measured by Taylor hyperpigmentation scale in 2 sun-protected body areas: (1) medial arm under the axilla, and (2) lateral upper thigh.
Six out of 16 (37.5%) subjects experienced significant improvements in glutathione group and 3 (18.75%) subjects in placebo group. Nonetheless, within 6 months after the last glutathione injection, gradual skin color improvements disappeared, leaving only 1 (6.2%) out of 16 subjects with skin color improvements. Both groups (glutathione and placebo) did not demonstrate significant difference in skin color ( and , respectively).
This study demonstrated poor outcomes of glutathione in terms of efficacy as well as cost-effectiveness.
Changes in melanin index as measured by Mexameter in six body parts (sun-exposed and sun-protected). Other measured parameters including quantitative evaluation of UV spots, pores, and evenness measured by VISIA™ CR system, TEWL (transepidermal water loss) by Tewameter® TM300, water content by Corneometer® CM825, skin elasticity by Cutometer MPA580®, and skin wrinkles by Visioscan®.
On all subjects, melanin index and UV spot on all areas including the face and arm of GSSG and GSH groups tend to be lower than placebo group (). No significant difference was observed between GSSG and GSH groups. Subgroup analysis of subjects aged >40 years who received GSH (N = 7) showed lower melanin index than placebo arm (N = 10, ). Melanin index on sun-exposed area of the left forearm in GSH group was lower than placebo ().
GSSG and GSH showed significant effects toward melanin index only in some areas of the skin and certain age groups, especially subjects with age >40 years on sun-exposed area of right forearm (). GSH was effective to reduce facial wrinkles at least in some anatomical locations, as compared to placebo. Both glutathione preparations increased skin elasticity either in sun-exposed or sun-protected areas.
