Fig. 14.1
Tranexamic acid (trans-4-amonimethyl cyclohexane carboxylic acid)
Keratinocytes produce PA. Epidermal basal cells contain plasminogen molecules. Plasmin plays a role in the release of basic fibroblast growth factor, which is a potent growth factor for melanocytes [4]. Wu et al reported that TA in animal models has been shown to prevent ultraviolet light-induced pigmentation by preventing the binding of plasminogen to keratinocytes that resulted in a decrease in the tyrosinase activity of melanocytes [5]. He further stated that research by Zhang et al showed that TA is able to inhibit melanogenesis by interfering with the catalytic reaction of tyrosinase. Sarkar et al showed that TA is able to decrease α-melanocyte-stimulating hormone that stimulates melanin synthesis [6].
Karn et al evaluated the efficacy of TA as an adjunct to topical hydroquinone and sunscreen for melasma in 260 subjects [7]. In this randomized controlled trial done for 3 months, Group A received TA at a dose of 250 mg twice daily in addition to topical treatment, and Group B received topical treatment alone. Results indicated that there was a statistically significant decrease in the mean Melasma Assessment Severity Index (MASI) from baseline to 8 and 12 weeks among group A patients (11.08 ± 2.91 vs. 8.95 ± 2.08 at week 8 and vs. 7.84 ± 2.44 at week 12; p < 0.05 for both). Among group B patients, the decrease in mean score was significant at 8 weeks and insignificant at 12 weeks follow-up (11.60 ± 3.40 vs. 9.9 ± 2.61 at 8 weeks and vs. 9.26 ± 3 at 12 weeks; p < 0.05 for former but p > 0.05 for later). TA was found effective for the treatment of melasma at a low dose of 250 mg twice a day for at least 3 months.
Because of its antihemorrhagic property, it is not safe to use it for a long duration. Unwanted side effects can include venous thromboembolism, myocardial infarction, cerebrovascular accidents and pulmonary embolism.
14.3 Pycnogenol/Procyanidin
Pycnogenol is derived from the extract of the French maritime pine bark, Pinus pinaster (Fig. 14.2). It contains 65–75 % procyanidin as its main ingredient. It also contains other phenolic compounds such as catechin, epicatechin, caffeic acid and ferulic acid [8]. It was found to be more potent than vitamins C and E in vitro, in its anti-inflammatory and antioxidant properties [9]. It has been demonstrated to protect against UV-induced erythema through mechanisms that inhibit the expression of nuclear factor (NF-kB) [8].
Fig. 14.2
French maritime pine bark
Ni et al in an open-label trial of 30 Chinese women with melasma taking oral Pycnogenol 25 mg thrice daily for 30 days demonstrated an 80 % response rate with no significant side effects observed [9]. Handog et al, in a randomized, double-blind, placebo-controlled trial, reported that a fixed combination of oral procyanidin plus vitamins A, C, E given to 60 Filipino women with bilateral epidermal melasma resulted in a significant decrease in the degree of pigmentation in both malar regions (left: 165.85 ± 70.909; right: 161.33 ± 61.824, p < 0.0001). MASI scores showed similar significant improvements (left: 2.4862 ± 1.67816; right: 1.8889 ± 1.67110, p < 0.001). Procyanidin + vitamins A, C, E proved to be safe and well tolerated, with minimal adverse events. The combination contained 24 mg of procyanidin and was taken twice daily for 8 weeks. No serious adverse reaction was reported in the study [10].
14.4 Polypodium leucotomos (PL)
Polypodium leucotomos is a tropical species of fern (Fig. 14.3) that contains polyphenols, which are potent inhibitors of reactive oxygen species with anti-inflammatory, antioxidant, and photoprotective properties. PL inhibits matrix metalloproteinase-1-photoinduced membrane damage and reduces psoralen/UVA-induced phototoxicity [11].
Fig. 14.3
Polypodium leucotomos
Martin et al demonstrated the clinical efficacy of P. leucotomos for the treatment of melasma. Female subjects aged 18–50 years with epidermal melasma (N = 21) were randomized to receive oral P. leucotomos or placebo twice daily for 12 weeks. Each subject applied SPF45 sunscreen daily. Efficacy measures included changes in the Melasma Quality of Life Scale, MASI and clinical evaluation by the study investigator. Plain and UV-lamp photographs obtained at baseline and weeks 4, 8, and 12 were evaluated by an independent, blinded investigator. At 12 weeks, patients treated with P. leucotomos had significantly decreased mean MASI scores (5.7–3.3; p < 0.05), whereas the placebo group did not (4.7–5.7; p = NS). Photographic assessment revealed that mild and marked improvement was achieved by 43 and 17 % of P. leucotomos-treated patients, respectively, versus 14 and 0 % of placebo-treated patients. Similarly, patient self-assessments revealed 50 and 13 % of patients achieved mild and marked improvement, respectively, versus 17 and 0 % for placebo-treated patients. Seventeen percent of placebo-treated patients reported worsened melasma severity versus none of P. leucotomos-treated patients [12].
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