This randomized controlled clinical trial, conducted by Wahab et al., aimed to evaluate the efficacy of topical and oral glutathione (GSH) in skin lightening and to determine if combination therapy is superior to monotherapy. Glutathione is widely recognized for its antioxidant and antimelanogenesis properties, and this study investigated its potential as a depigmenting agent.
Study Design and Participants
- Type of Study: Double-blind, randomized controlled clinical trial in Hasanuddin University Hospital, Makassar, Indonesia.
- Participants:
- 46 healthy females aged 25–50 years with Fitzpatrick skin types IV and V.
- Exclusion criteria included individuals with a history of skin cancer, glutathione intake in the previous month, pregnancy, smoking, or breastfeeding. Participants who had dermatoses or excessive sun exposure were also excluded.
Study Protocol
- Participants were divided into two equal groups (n=23 each).
- All participants received either oral glutathione (600 mg/day, twice daily) or a placebo.
- Each participant was also instructed to apply topical glutathione (2% with vitamin C) or a placebo to the right and left cheeks, respectively, in a blinded manner.
- The combination treatment group applied glutathione both topically and orally.
- Skin color measurements were conducted at baseline and biweekly for eight weeks using two devices:
- Mexameter – Measured melanin index (MI).
- Chromameter – Measured skin brightness (L* score).
Outcome Measures
- Primary Outcome: Melanin index (MI) and L* score (brightness).
- Secondary Outcome: Safety, tolerability, and adverse effects.
Results
1. Demographics
- There were no significant differences between the groups regarding age or skin type.
- Mean Age (years):
- Oral placebo group – 29.7 ± 8.3
- Oral glutathione group – 30.2 ± 7.8
- Fitzpatrick Skin Type:
- Type IV: 56.5% (placebo), 43.5% (GSH)
- Type V: 43.5% (placebo), 56.5% (GSH)
- P > 0.05 (no significant difference).
2. Efficacy Analysis
Melanin Index (MI) – Skin Pigmentation
- Baseline MI showed no significant differences among the four groups (P = 0.535).
- At week 8, significant differences were noted among the groups (P = 0.033).
- Group Comparisons at Week 8:
- Group 1 (topical and oral placebo) – MI: 385.69 ± 94.38
- Group 2 (topical GSH, oral placebo) – MI: 330.69 ± 87.90
- Group 3 (oral GSH, topical placebo) – MI: 347.00 ± 81.77
- Group 4 (topical and oral GSH) – MI: 314.35 ± 70.13
- P-values for Group Comparisons:
- Group 1 vs Group 2: P = 0.029
- Group 1 vs Group 4: P = 0.005
- Group 2 vs Group 4: P = 0.511
- Interpretation: Group 4 (combination therapy) showed the most significant reduction in melanin levels, with a P < 0.05 indicating statistically significant results.
L Score – Skin Brightness*
- At baseline, there were no significant differences in L* scores among groups (P = 0.092).
- A significant increase in L* score was observed by week 6 (P = 0.040) and continued through week 8 (P = 0.001).
- L Scores at Week 8*:
- Group 1 – 46.39 ± 2.99
- Group 2 – 49.07 ± 4.42
- Group 3 – 50.16 ± 3.38
- Group 4 – 51.21 ± 3.35
- P-values for Group Comparisons:
- Group 1 vs Group 2: P = 0.046
- Group 1 vs Group 4: P = 0.000
- Group 2 vs Group 4: P = 0.045
- Interpretation: Group 4 (combination therapy) exhibited the highest L* score, indicating the greatest improvement in skin brightness.
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Safety and Tolerability
- No participants reported adverse effects such as erythema, edema, pruritus, or stinging sensations.
- No systemic side effects were observed, and the treatment was well tolerated by all participants.
Discussion
- The combination of oral and topical glutathione demonstrated superior results compared to monotherapy or placebo.
- Participants in the combination group (Group 4) had the lowest melanin index and highest skin brightness score by the end of the study.
- These findings suggest that combination therapy may provide enhanced skin-lightening effects by leveraging both systemic and localized mechanisms.
Conclusion
- Topical and oral glutathione are effective skin-whitening agents, with combination therapy providing the most significant results.
- The data supports the use of glutathione for skin-lightening applications, particularly in populations with darker skin tones (Fitzpatrick IV and V).
- Further large-scale studies with longer follow-up periods are recommended to validate these findings.
For full details, refer to the original article: https://pubmed.ncbi.nlm.nih.gov/33871071/