INTRODUCTION
The etiology of skin dyschromia remains complex and its treatment remains challenging, particularly for melasma. Melasma is a common, persistent disorder of hyperpigmentation affecting a significant portion of the population, particularly women living in areas with intense ultraviolet radiation.1,2 It is characterized by symmetric hyperpigmented macules or patches with irregular borders, most often distributed on the forehead, cheeks, and along the jawline.3,4 The causes of melasma remain unknown, although some triggering factors are described, such as sun exposure, pregnancy, use of oral contraceptives and steroids, hepatopathies, use of photosensitizing drugs, inflammatory processes of the skin, and stressful events.5 Melasma, hyperpigmentation, and post-inflammatory hyperpigmentation (PIH), are prevalent in all Fitzpatrick skin types, especially in those with darker skin tones.6 These dermatologic conditions are a leading cause for cosmetic consultation, and account for the high demand for effective skin lightening therapies.7 Studies have shown that hyperpigmentation, particularly melasma, greatly affects quality of life, causing psychosocial distress.8 Treatments for melasma include topical depigmenting agents, such as hydroquinone (HQ (2-4%)), tretinoin, azelaic acid, superficial peeling agents, and lasers. Results with these treatments are often temporary, as the discoloration generally returns with continued exposure to the sun.9 Kojic acid and niacinamide, two well-known skin lightening agents, either alone or in combination with other actives, have been demonstrated to be effective in reducing the hyperpigmentation, including melasma.10-14 Tranexamic acid (trans-4-aminomethylcyclohexanecarboxylic acid: TXA) is a plasmin inhibitor used to prevent fibrinolysis to reduce blood loss.
It exerts its effect by reversibly blocking lysine bindingsites on plasminogen, thus inhibiting plasminogen activator (PA) from converting plasminogen to plasmin. While plasminogen also exists in human epidermal basal cells and cultured human keratinocytes are known to produce PA, there is basic rationale that TXA may affect keratinocyte functions and interactions. 8 The anti-plasmin activity of TXA is thought as being the main mechanism of its hyperpigmentary effect. In several studies, treatment with topical TXA (2-5%) was shown to be well tolerated, with no serious side effects reported.5,10 In a 12-week, single-center, clinical study, a novel topical facial serum containing 3% tranexamic acid, 1% kojic acid, and 5% niacinamide, was evaluated for its effectiveness in treating mild to moderate melasma, PIH, and hyperpigmentation in Brazilianfemale subjects. Efficacy parameters included expert clinical grading, bioinstrumental measurement, self-assessment questionnaires,and subjective and objective cutaneous tolerability assessment. TXA's mechanism of action was also assessed utilizing in vitro cultures of human epidermal melanocytes.
METHODS
In vivo Clinical Study
The clinical study was conducted at a contract research organization (CRO) in São Paulo, Brazil from May to September 2017 (Allergisa-SP, Brazil). Written informed consent was obtained from all study subjects prior to enrollment. The study was conductedin accordance to the guidelines outlined by the Ethical Principles for Medical Research Involving Human Subjects-Helsinki Declaration (1964) and its successive updates.16 The CRO adhered to the Good Clinical Practice (GCP) guidelines throughout the course of the study. An Independent Ethics Committee (IEC) ((Investiga - Instituto de Pesquisas, registered by the National Research Ethics Commission (CONEP)) approved the study.
The clinical study was conducted at a contract research organization (CRO) in São Paulo, Brazil from May to September 2017 (Allergisa-SP, Brazil). Written informed consent was obtained from all study subjects prior to enrollment. The study was conductedin accordance to the guidelines outlined by the Ethical Principles for Medical Research Involving Human Subjects-Helsinki Declaration (1964) and its successive updates.16 The CRO adhered to the Good Clinical Practice (GCP) guidelines throughout the course of the study. An Independent Ethics Committee (IEC) ((Investiga - Instituto de Pesquisas, registered by the National Research Ethics Commission (CONEP)) approved the study.
Formulation
The formulation evaluated was a hydroglycolic topical facial serum (Discoloration Defense, SkinCeuticals Inc., New York, NY) containing the following ingredients: 3% tranexamic acid (TXA), 1% kojic acid, 5% niacinamide, and 5% hydroxyethylpiperazine ethane sulfonic acid (HEPES).
Subjects
Fifty-five healthy Brazilian female subjects aged 27 to 60 years (mean age, 41 years) were enrolled in the 12-week clinical study. Subjects were non-smokers with Fitzpatrick skin types I-IV. At least 50% of subjects had self-perceived sensitive skin. The inclusion criteria for the study included a clinical evaluation score by a dermatologist on a visual analog scale for mild tomoderate hyperpigmentation, skin texture roughness, and skin tone unevenness. A dermatologist identified mild to moderate PIH (according to a visual analog scale) in 36 of the 55 subjects, and mild to moderate melasma (according to a modified MASIscale) in 48 of the 55 subjects.
The formulation evaluated was a hydroglycolic topical facial serum (Discoloration Defense, SkinCeuticals Inc., New York, NY) containing the following ingredients: 3% tranexamic acid (TXA), 1% kojic acid, 5% niacinamide, and 5% hydroxyethylpiperazine ethane sulfonic acid (HEPES).
Subjects
Fifty-five healthy Brazilian female subjects aged 27 to 60 years (mean age, 41 years) were enrolled in the 12-week clinical study. Subjects were non-smokers with Fitzpatrick skin types I-IV. At least 50% of subjects had self-perceived sensitive skin. The inclusion criteria for the study included a clinical evaluation score by a dermatologist on a visual analog scale for mild tomoderate hyperpigmentation, skin texture roughness, and skin tone unevenness. A dermatologist identified mild to moderate PIH (according to a visual analog scale) in 36 of the 55 subjects, and mild to moderate melasma (according to a modified MASIscale) in 48 of the 55 subjects.
Treatment Protocol
The topical serum was evenly applied across a cleansed face in the morning and evening. The serum's first application was conducted at the CRO during the inclusion visit (Day 0). Following the inclusion visit, subjects applied the topical serum at home for 12 weeks (D1-D83). The subjects were also provided with a sunscreen (SPF 70), which was applied to the face in the morning and as needed throughout the day prior to sun exposure.
The topical serum was evenly applied across a cleansed face in the morning and evening. The serum's first application was conducted at the CRO during the inclusion visit (Day 0). Following the inclusion visit, subjects applied the topical serum at home for 12 weeks (D1-D83). The subjects were also provided with a sunscreen (SPF 70), which was applied to the face in the morning and as needed throughout the day prior to sun exposure.
Evaluation Parameters and Methods
Assessment of Facial Dyschromia
Clinical scoring of melasma according to a modified MASI scale was conducted by a dermatologist at pre-treatment baseline and weeks 2, 4, 8, and 12 on 48 of the 55 subjects who were identified as having melasma. The modified MASI score was calculated by subjective assessment of two factors: area of involvement (A) and darkness (D), with the forehead (f), right malar region (rm), left malar region (lm), and chin (c), corresponding to 30%, 30%, 30%, and 10% of the total face, respectively.
The modified MASI was scored as follows and the range of the total score was 0 to 24:
mMASI = 0.3A(f)D(f) + 0.3A(lm)D(lm) + 0.3A(rm)D(rm) + 0.1A(c)D(c)
Expert clinical grading evaluations were conducted at pretreatment baseline, weeks 2, 4, 8, and 12. Facial dyschromiaparameters were clinically graded on a modified Griffith's 5-point scale, with half-point increments, where 0=none (best possible condition) and 4=severe (worst possible condition). Efficacy measures included visual evaluation and grading by a dermatologist under standard daylight assessing the following attributes: appearance of PIH, hyperpigmentation, and skin texture. Skin tone homogeneity was clinically graded on a 4-point scale, with half-point increments, where 0 =none (best possible condition) and 3=severe (worst possible condition).
Tolerability Assessment
Tolerability assessments were conducted at pre-treatment baseline, weeks 2, 4, 8, and 12. Tolerability parameters weregraded on a scale where 0=none; 1=mild; 2=moderate; and 3=severe. Clinically-graded objective irritation parameters includederythema, dryness, scaling, and edema. In addition, subjects self-assessed burning, stinging, itching, tightness, and tingling.
Bioinstrumentation
Standardized digital photographs of subjects were taken at the pre-treatment baseline, week 2, week 4, week 8, and week 12 time points using the VISIA-CR (Canfield Scientific, Fairfield, NJ) imaging system.
Assessment of Facial Dyschromia
Clinical scoring of melasma according to a modified MASI scale was conducted by a dermatologist at pre-treatment baseline and weeks 2, 4, 8, and 12 on 48 of the 55 subjects who were identified as having melasma. The modified MASI score was calculated by subjective assessment of two factors: area of involvement (A) and darkness (D), with the forehead (f), right malar region (rm), left malar region (lm), and chin (c), corresponding to 30%, 30%, 30%, and 10% of the total face, respectively.
The modified MASI was scored as follows and the range of the total score was 0 to 24:
mMASI = 0.3A(f)D(f) + 0.3A(lm)D(lm) + 0.3A(rm)D(rm) + 0.1A(c)D(c)
Expert clinical grading evaluations were conducted at pretreatment baseline, weeks 2, 4, 8, and 12. Facial dyschromiaparameters were clinically graded on a modified Griffith's 5-point scale, with half-point increments, where 0=none (best possible condition) and 4=severe (worst possible condition). Efficacy measures included visual evaluation and grading by a dermatologist under standard daylight assessing the following attributes: appearance of PIH, hyperpigmentation, and skin texture. Skin tone homogeneity was clinically graded on a 4-point scale, with half-point increments, where 0 =none (best possible condition) and 3=severe (worst possible condition).
Tolerability Assessment
Tolerability assessments were conducted at pre-treatment baseline, weeks 2, 4, 8, and 12. Tolerability parameters weregraded on a scale where 0=none; 1=mild; 2=moderate; and 3=severe. Clinically-graded objective irritation parameters includederythema, dryness, scaling, and edema. In addition, subjects self-assessed burning, stinging, itching, tightness, and tingling.
Bioinstrumentation
Standardized digital photographs of subjects were taken at the pre-treatment baseline, week 2, week 4, week 8, and week 12 time points using the VISIA-CR (Canfield Scientific, Fairfield, NJ) imaging system.
Full frontal, left, and right profile views of the face were obtained, under standard visible, crossed-polarized, and parallel-polarized lights.
The melanin index (MI) and erythema index (EI) scores of lesional melasma and PIH skin were measured in triplicate usinga colorimeter (Mexameter MX 18, Courage + Khazaka GmbH, Koln, Germany). Measurements of the lesional areas, as well as the adjacent perilesional normal skin (control site), were captured. The difference between the control and the lesionalareas was calculated.
Subject Self-Assessment via Questionnaires
Subjects responded to questions regarding the formula's aesthetics and perceived efficacy throughout the course of the study.
Statistical Analysis
All subjects who completed the clinical study were included in the statistical analysis. Data were tested for normal distribution with the Shapiro-Wilk test, using a cutoff value of P <0.01 for efficacy and tolerability data. Efficacy and tolerability of the test serum was evaluated by comparing the post-treatment data to the pre-treatment baseline data for each attribute. The significance of change was determined using either a paired t-test for normally distributed data, or a Wilcoxon signed rank test for non-normal data. The cutoff value for significance was P<0.05. Instrumental data were similarly evaluated. The mean percent changes from pre-treatment baseline were reported at each time point for each attribute. The statistical analysis was carried out using the following software: MINITAB 14, STATA and XLSTAT 2017.
The melanin index (MI) and erythema index (EI) scores of lesional melasma and PIH skin were measured in triplicate usinga colorimeter (Mexameter MX 18, Courage + Khazaka GmbH, Koln, Germany). Measurements of the lesional areas, as well as the adjacent perilesional normal skin (control site), were captured. The difference between the control and the lesionalareas was calculated.
Subject Self-Assessment via Questionnaires
Subjects responded to questions regarding the formula's aesthetics and perceived efficacy throughout the course of the study.
Statistical Analysis
All subjects who completed the clinical study were included in the statistical analysis. Data were tested for normal distribution with the Shapiro-Wilk test, using a cutoff value of P <0.01 for efficacy and tolerability data. Efficacy and tolerability of the test serum was evaluated by comparing the post-treatment data to the pre-treatment baseline data for each attribute. The significance of change was determined using either a paired t-test for normally distributed data, or a Wilcoxon signed rank test for non-normal data. The cutoff value for significance was P<0.05. Instrumental data were similarly evaluated. The mean percent changes from pre-treatment baseline were reported at each time point for each attribute. The statistical analysis was carried out using the following software: MINITAB 14, STATA and XLSTAT 2017.
In Vitro Study
Monolayer Cultures of Human Epidermal Melanocytes
Inhibition by TXA on PGE2-induced melanogenesis was evaluated in cultured human epidermal melanocytes. Normal human epidermal melanocytes from four different donors obtained from ZenBio (Research Triangle Park, NC, USA) were plated at a density of 10,000 cells per cm2 and grown in serumfree melanocyte growth medium. After 3 days, when the cells reached 70% confluence, medium was changed, and cells were treated over 72 hrs with 30 nM PGE2, and 50 or 100 μMM TXA or combination of PGE2 (30 nM) + TXA (50 or 100 μM). Control cells were treated with equivalent amount of vehicle (ethanol for PGE2, water for TXA) without any active. After 4 days of cell growth, the cells were harvested, and the melanin content was analyzed using OD measurement at 405 nm. The cells were stained with Fontana Mason stain for melanin quantification.
Monolayer Cultures of Human Epidermal Melanocytes
Inhibition by TXA on PGE2-induced melanogenesis was evaluated in cultured human epidermal melanocytes. Normal human epidermal melanocytes from four different donors obtained from ZenBio (Research Triangle Park, NC, USA) were plated at a density of 10,000 cells per cm2 and grown in serumfree melanocyte growth medium. After 3 days, when the cells reached 70% confluence, medium was changed, and cells were treated over 72 hrs with 30 nM PGE2, and 50 or 100 μMM TXA or combination of PGE2 (30 nM) + TXA (50 or 100 μM). Control cells were treated with equivalent amount of vehicle (ethanol for PGE2, water for TXA) without any active. After 4 days of cell growth, the cells were harvested, and the melanin content was analyzed using OD measurement at 405 nm. The cells were stained with Fontana Mason stain for melanin quantification.
RESULTS
In vivo Clinical Study Results
Assessment of Facial Dyschromia
All clinically-graded skin attribute parameters showed a statistically-significant decrease (improvement) in scores at all time points compared to baseline (Table 1). Improvements were apparent as early as 2 weeks and were maintained through the study conclusion (week 12). Significant improvements were observed in the appearance of PIH, hyperpigmentation, skin texture, and skin tone homogeneity. A significant reduction in melasma, as evaluated by the mMASI scale, was also observed as early as 2 weeks, and at all time points thereafter.
Assessment of Facial Dyschromia
All clinically-graded skin attribute parameters showed a statistically-significant decrease (improvement) in scores at all time points compared to baseline (Table 1). Improvements were apparent as early as 2 weeks and were maintained through the study conclusion (week 12). Significant improvements were observed in the appearance of PIH, hyperpigmentation, skin texture, and skin tone homogeneity. A significant reduction in melasma, as evaluated by the mMASI scale, was also observed as early as 2 weeks, and at all time points thereafter.
Standardized Photography - VISIA-CR
Standardized digital images of three selected study subjects at pre-treatment baseline (left) and week 12 (right) (Figure 1) demonstrated improvement in hyperpigmentation, PIH, and melasma, which were representative of average results for the overall study panel.
Standardized digital images of three selected study subjects at pre-treatment baseline (left) and week 12 (right) (Figure 1) demonstrated improvement in hyperpigmentation, PIH, and melasma, which were representative of average results for the overall study panel.
Mexameter® Measurements
Pigmentation measurements showed significant improvements compared to pre-treatment baseline (Table 2). The melanin index (MI) scores of the lesional melasma skin decreased significantly in as early as 4 weeks. By week 8, the lesional melasma skinshowed a decrease in MI by as much as 9%. The perilesional normal skin (control site) also showed a significant decrease in MI by week 4. On week 8 and 12, the decrease in MI was significantly higher for the lesional melasma skin as compared to the control site (P=0.008 and P=0.028, respectively). This suggests that the topical serum had a greater effect in improving lesional melasma skin as compared to unaffected, normal skin.
Pigmentation measurements showed significant improvements compared to pre-treatment baseline (Table 2). The melanin index (MI) scores of the lesional melasma skin decreased significantly in as early as 4 weeks. By week 8, the lesional melasma skinshowed a decrease in MI by as much as 9%. The perilesional normal skin (control site) also showed a significant decrease in MI by week 4. On week 8 and 12, the decrease in MI was significantly higher for the lesional melasma skin as compared to the control site (P=0.008 and P=0.028, respectively). This suggests that the topical serum had a greater effect in improving lesional melasma skin as compared to unaffected, normal skin.
Similar results were observed for PIH. As early as 4 weeks, the melanin index of the lesional PIH skin significantly decreased, which continued through week 12. The perilesional normal skin (control site) also demonstrated a significant decrease in skin color with treatment at weeks 4 and 8. The decrease in MI was significantly greater in lesional PIH skin as compared to perilesional normal skin on week 2 (P=0.048), week 8 (P=0.002), and week 12 (P=0.014). The data demonstrates that the facial serum has greater efficacy on lesional PIH skin as compared to unaffected, normal skin.
The erythema index (EI) showed no significant change at most time points for both melasma and PIH. A significant decrease in EI scores was observed at week 8 for both the lesional melasma skin and perilesional normal skin, and week 8 for the lesional PIH skin, respectively (data not shown). However, no significant changes in EI were achieved in lesional skin as compared to perilesional normal skin for both melasma and PIH.
Self-Assessment Questionnaires
Overall satisfaction with the serum's aesthetics and efficacy were significant at all time points (data not shown).
Safety and Local intolerances
Local cutaneous tolerability was acceptable (data not shown). Minor transient effects such as erythema (2/55), itching (1/55), pruritis (1/55), redness (1/55), or stinging (1/55) were observed during the course of the study. Local intolerances were transient and quickly resolved after the product application. From the dermatologist's observation and conclusion, the product was considered to have very good tolerability and cutaneous acceptability.
In Vitro Study Results
TXA Inhibition of PGE2 Induced Melanogenesis
30nM PGE2 significantly stimulated melanin production in human epidermal melanocytes (HEM) compared to control cells (P=0.02; Figure 2). TXA alone showed no effect on melanin content of HEM. 50 μM and 100 μM TXA treatment of PGE2- stimulated melanocytes demonstrated a significant decrease in melanin content (P=0.046 and P=0.023, respectively. There was no significant difference between 50 μM TXA and 100 μM TXA.
TXA Inhibition of PGE2 Induced Melanogenesis
30nM PGE2 significantly stimulated melanin production in human epidermal melanocytes (HEM) compared to control cells (P=0.02; Figure 2). TXA alone showed no effect on melanin content of HEM. 50 μM and 100 μM TXA treatment of PGE2- stimulated melanocytes demonstrated a significant decrease in melanin content (P=0.046 and P=0.023, respectively. There was no significant difference between 50 μM TXA and 100 μM TXA.
This in vitro study demonstrated that PGE2 stimulation is a reliable method for melanogenesis studies in normal human epidermal melanocytes. In this model, TXA dose dependently inhibited melanogenesis. The observation that TXA alone had no significant effect on melanogenesis also indicates that the mechanism of action of TXA involves blocking PGE2-induced melanin production in melanocytes.
DISCUSSION
It has been well established that TXA delivered orally or by injection is an effective approach in the treatment of melasma. However, only a limited number of studies have assessed the effectiveness of topical TXA on facial dyschromia. The objective of this study was to demonstrate the clinical efficacy of a novel topical facial serum containing 1% kojic acid, 5% niacinamide, and 3% TXA in improving key markers of discoloration. Kojicacid is a well-known skin-lightening agent that acts through inhibiting the rate limiting enzyme tyrosinase.10,11 It has been suggested that niacinamide suppresses melanin transfer from melanocytes to keratinocytes.13 Finally, we have established that TXA controls pigmentation by inhibiting the release of inflammatory mediators, specifically prostaglandins, which are involved in melanogenesis. Therefore, the combination of these three ingredients with distinct modes of action in an optimized hydroglycolic serum, synergistically target multiple biological pathways associated with the development of discoloration.
After 12 weeks of topical product application, an average 81% reduction in PIH was reported while melasma and hyperpigmentation improved by 60%. Marked improvements in skin tone and skin homogeneity were also observed, by 54% and 59%, respectively. The significant decrease in melanin index scores on melasma and PIH lesional skin compared to perilesional normal skin provides further evidence of product efficacy. In terms of perceived effectiveness, as measured by self-assessment questionnaires, questionnaires, subjects rated the topical serum highly favorable for both efficacy and aesthetics. Overall satisfaction with the serum was over 90% at all time points, which is promising considering the lack of satisfaction with non-prescription topical discoloration treatments. The role of PGE2 in the signaling pathways involved in growth, differentiation, and apoptosis of melanocytes has been well-established.23 PGE2 is also released abundantly by keratinocytes following exposure to UV radiation (UVR).23,24 Keratinocyte-derived PGE2 stimulates the formation of dendrites in melanocytes and activates melanocyte and tyrosinase activity. TXA inhibits PG production, and thus reduces the melanocyte tyrosinase activity.14 We demonstrated that 50-100 μM TXA suppressed themelanogenesis of PGE2-stimulated melanocytes in culture. This function of TXA is particularly relevant in the treatment of melasma,hyperpigmentation, and PIH.
In conclusion, this study demonstrates that a novel topical facial serum containing 3% TXA, 1% kojic acid, and 5% niacinamide,is a safe and effective treatment for melasma, hyperpigmentation, and PIH. In addition, TXA's mechanism of action has beenfurther clarified by an in vitro study showing the suppression of PGE2-induced inflammation in normal human epidermal melanocytes.
After 12 weeks of topical product application, an average 81% reduction in PIH was reported while melasma and hyperpigmentation improved by 60%. Marked improvements in skin tone and skin homogeneity were also observed, by 54% and 59%, respectively. The significant decrease in melanin index scores on melasma and PIH lesional skin compared to perilesional normal skin provides further evidence of product efficacy. In terms of perceived effectiveness, as measured by self-assessment questionnaires, questionnaires, subjects rated the topical serum highly favorable for both efficacy and aesthetics. Overall satisfaction with the serum was over 90% at all time points, which is promising considering the lack of satisfaction with non-prescription topical discoloration treatments. The role of PGE2 in the signaling pathways involved in growth, differentiation, and apoptosis of melanocytes has been well-established.23 PGE2 is also released abundantly by keratinocytes following exposure to UV radiation (UVR).23,24 Keratinocyte-derived PGE2 stimulates the formation of dendrites in melanocytes and activates melanocyte and tyrosinase activity. TXA inhibits PG production, and thus reduces the melanocyte tyrosinase activity.14 We demonstrated that 50-100 μM TXA suppressed themelanogenesis of PGE2-stimulated melanocytes in culture. This function of TXA is particularly relevant in the treatment of melasma,hyperpigmentation, and PIH.
In conclusion, this study demonstrates that a novel topical facial serum containing 3% TXA, 1% kojic acid, and 5% niacinamide,is a safe and effective treatment for melasma, hyperpigmentation, and PIH. In addition, TXA's mechanism of action has beenfurther clarified by an in vitro study showing the suppression of PGE2-induced inflammation in normal human epidermal melanocytes.
DISCLOSURES
Dr. Desai, Dr. Ayres, and Dr. Bak have served as consultants to SkinCeuticals. Stephen Lynch, Susana Raab, Ana Du, DesTeneeGreen, Janet Wangari-Talbot, and Qian Zheng are employed by L'Oreal Research and Innovation. Cezary Skobowiat was employedby L'Oreal Research and Innovation at the time of this work. Megan Manco was employed by SkinCeuticals at the time of this work.
ACKNOWLEDGMENTS
The authors would like to thank Kumar Pillai, PhD for his critical review and editorial assistance with this manuscript.
REFERENCES
1. Victor FC1, Gelber J, Rao B, Melasma: a review. J Cutan Med Surg. 2004;8(2):97-102.
2. Grimes PE. Melasma: etiologic and therapeutic considerations. Arch Dermatol. 1995;131:1453-7.
3. Miot LD, Miot HA, Silva MG, Marques ME. Physiopathology of melasma. An Bras Dermatol. 2009;84(6):623-35.
4. Perper M, Eber AE, Fayne R, Verne SH, Magno RJ, Cervantes J, ALharbi M, ALOmair I, Alfuraih A, Nouri K. Tranexamic acid in the treatment of melasma: a review of the literature. Am J Clin Dermatol. 2017;18(3):373-381.
5. Taraz M, Niknam S, Ehsani AH. Tranexamic acid in treatment of melasma: A comprehensive review of clinical studies. Dermatol Ther. 2017;30(3).
6. Molinar VE, Taylor SC, Pandya AG. What's new in objective assessment and treatment of facial hyperpigmentation? Dermatol Clin. 2014;32(2):123-35.
7. Sofen B, Prado G, Emer J., Melasma and postinflammatory hyperpigmentation: management update and expert opinion. Skin Therapy Lett. 2016;21(1):1-7.
8. Ikino JK, Nunes DH, Silva VP, Frode TS, Sens MM. Melasma and assessment of the quality of life in Brazilian women. An Bras Dermatol. 2015;90(2):196 200.
2. Grimes PE. Melasma: etiologic and therapeutic considerations. Arch Dermatol. 1995;131:1453-7.
3. Miot LD, Miot HA, Silva MG, Marques ME. Physiopathology of melasma. An Bras Dermatol. 2009;84(6):623-35.
4. Perper M, Eber AE, Fayne R, Verne SH, Magno RJ, Cervantes J, ALharbi M, ALOmair I, Alfuraih A, Nouri K. Tranexamic acid in the treatment of melasma: a review of the literature. Am J Clin Dermatol. 2017;18(3):373-381.
5. Taraz M, Niknam S, Ehsani AH. Tranexamic acid in treatment of melasma: A comprehensive review of clinical studies. Dermatol Ther. 2017;30(3).
6. Molinar VE, Taylor SC, Pandya AG. What's new in objective assessment and treatment of facial hyperpigmentation? Dermatol Clin. 2014;32(2):123-35.
7. Sofen B, Prado G, Emer J., Melasma and postinflammatory hyperpigmentation: management update and expert opinion. Skin Therapy Lett. 2016;21(1):1-7.
8. Ikino JK, Nunes DH, Silva VP, Frode TS, Sens MM. Melasma and assessment of the quality of life in Brazilian women. An Bras Dermatol. 2015;90(2):196 200.
9. K. Shankar, K. Ghodse, Aurangabadker S, et al. Evidence-based treatment for melasma: expert opinion and a review. Dermatol Ther (Heidelb). 2014;4(2):165 186.
10. Deo KS, Dash KN, Sharma YK, Virmani NC, Oberai C. Kojic acid vis-a-vis its combinations with hydroquinone and betamethasone valerate in melasma: a randomized, single blind, comparative study of efficacy and safety. Indian J Dermatol. 2013;58(4):281-5.
11. Monteiro RC, Kishore BN, Bhat RM, Sukumar D, Martis J, Ganesh HK. A comparative study of the efficacy of 4% hydroquinone vs 0.75% kojic acid cream in the treatment of facial melasma. Indian J Dermatol. 2013;58(2):157.
12. Navarrete-Sol J, Castanedo-Ca¡zares JP, Torres-ÃÂlvarez B, Oros-Ovalle C, Fuentes-Ahumada C, Gonzalez¡FJ, Martinez-Ramirez JD, Moncada B. A double-blind, randomized clinical trial of niacinamide 4% versus hydroquinone 4% in the treatment of melasma. Dermatol Res Pract. 2011;2011:379173.
13. Rolfe HM. A review of nicotinamide: treatment of skin diseases and potential side effects. J Cosmet Dermatol. 2014;13(4):324-8.
14. Tse, T. W., & Hui, E. Tranexamic acid: An important adjuvant in the treatment of melasma. J Cosmet Dermatol. 2013;12(1):57-66.
15. Byun SY, Chae JB, Na JI, Park KC. Significant improvement in crows feet after treatment with Jet-M and a mixed solution of copper GHK, oligo-hyaluronic acid, rhodiolar extract, tranexamic acid, and beta-glucan (GHR formulation). J Cosmet Laser Ther. 2016;18(5):293 5.
16. World Medical Association Declaration of Helsinki: Ethical Principles for Medical Research Involving Human Subjects (1964). Bull. World Health Org. 2001; 79(4): 373-374.
17. Lee JH, Park JG, Lim SH, Kim JY, Ahn KY, et al. Localized intradermal microinjection of tranexamic acid for treatment of melisma in Asian patients: a preliminary clinical trial. Dermatol Surg. 2006;32:626-631.
18. Maeda K, Naganuma M. Topical trans-4-aminomethyl cyclohexanecarboxylic acid prevents ultraviolet radiation-induced pigmentation. J Photochem Photobiol B. 1998;47:136-141.
19. Kondou S, Okada Y, Tomita Y. Clinical study of effect of tranexamic acid emulsion on melasma and freckles. Skin Res. 2007;6:309-315.
20. Na JI, Choi SY, Yang SH, Choi HR, Kang HY, et al. Effect of tranexamic acid on melasma: a clinical trial with histological evaluation. J Eur Acad Dermatol Venereol. 2013;27:1035-1039.
21. Nijo T. Treatment of melasma with tranexamic acid. Clin Res. 1979;13:3129- 3131.
22. Shital P. and Khushboo M. Tranexamic acid in melasma: a review. J Pigment Disord. 2015;2(12):1-4.
23. Starner RJ, McClelland L, Abdel?Malek Z, Fricke A, Scott G. PGE(2) is a UVR inducible autocrine factor for human melanocytes that stimulates tyrosinase activation. Exp Dermatol. 2010;19:682-4.
24. Kang-Rotondo CH1, Miller CC, Morrison AR, Pentland AP. Enhanced keratinocyte prostaglandin synthesis after UV injury is due to increased phospholipase activity. Am J Physiol. 1993;C396-401.
10. Deo KS, Dash KN, Sharma YK, Virmani NC, Oberai C. Kojic acid vis-a-vis its combinations with hydroquinone and betamethasone valerate in melasma: a randomized, single blind, comparative study of efficacy and safety. Indian J Dermatol. 2013;58(4):281-5.
11. Monteiro RC, Kishore BN, Bhat RM, Sukumar D, Martis J, Ganesh HK. A comparative study of the efficacy of 4% hydroquinone vs 0.75% kojic acid cream in the treatment of facial melasma. Indian J Dermatol. 2013;58(2):157.
12. Navarrete-Sol J, Castanedo-Ca¡zares JP, Torres-ÃÂlvarez B, Oros-Ovalle C, Fuentes-Ahumada C, Gonzalez¡FJ, Martinez-Ramirez JD, Moncada B. A double-blind, randomized clinical trial of niacinamide 4% versus hydroquinone 4% in the treatment of melasma. Dermatol Res Pract. 2011;2011:379173.
13. Rolfe HM. A review of nicotinamide: treatment of skin diseases and potential side effects. J Cosmet Dermatol. 2014;13(4):324-8.
14. Tse, T. W., & Hui, E. Tranexamic acid: An important adjuvant in the treatment of melasma. J Cosmet Dermatol. 2013;12(1):57-66.
15. Byun SY, Chae JB, Na JI, Park KC. Significant improvement in crows feet after treatment with Jet-M and a mixed solution of copper GHK, oligo-hyaluronic acid, rhodiolar extract, tranexamic acid, and beta-glucan (GHR formulation). J Cosmet Laser Ther. 2016;18(5):293 5.
16. World Medical Association Declaration of Helsinki: Ethical Principles for Medical Research Involving Human Subjects (1964). Bull. World Health Org. 2001; 79(4): 373-374.
17. Lee JH, Park JG, Lim SH, Kim JY, Ahn KY, et al. Localized intradermal microinjection of tranexamic acid for treatment of melisma in Asian patients: a preliminary clinical trial. Dermatol Surg. 2006;32:626-631.
18. Maeda K, Naganuma M. Topical trans-4-aminomethyl cyclohexanecarboxylic acid prevents ultraviolet radiation-induced pigmentation. J Photochem Photobiol B. 1998;47:136-141.
19. Kondou S, Okada Y, Tomita Y. Clinical study of effect of tranexamic acid emulsion on melasma and freckles. Skin Res. 2007;6:309-315.
20. Na JI, Choi SY, Yang SH, Choi HR, Kang HY, et al. Effect of tranexamic acid on melasma: a clinical trial with histological evaluation. J Eur Acad Dermatol Venereol. 2013;27:1035-1039.
21. Nijo T. Treatment of melasma with tranexamic acid. Clin Res. 1979;13:3129- 3131.
22. Shital P. and Khushboo M. Tranexamic acid in melasma: a review. J Pigment Disord. 2015;2(12):1-4.
23. Starner RJ, McClelland L, Abdel?Malek Z, Fricke A, Scott G. PGE(2) is a UVR inducible autocrine factor for human melanocytes that stimulates tyrosinase activation. Exp Dermatol. 2010;19:682-4.
24. Kang-Rotondo CH1, Miller CC, Morrison AR, Pentland AP. Enhanced keratinocyte prostaglandin synthesis after UV injury is due to increased phospholipase activity. Am J Physiol. 1993;C396-401.
AUTHOR CORRESPONDENCE
Stephen Lynch PhD stephen.lynch@rd.loreal.com
