الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
 |  | from | 152 |  |  |
| | | from | 152 | | |
Abstract
SUMMARY Melasma is an acquired hypermelanosis characterized by light to dark-brown macules and patches on sun-exposed areas. Most cases of melasma occur in women in the reproductive age with darker skin types, but all ages, races, and skin colours may be affected. Different therapeutic modalities have been used in the treatment of melasma including hydroquinone, retinoic acid, kojic acid, peeling agents like glycolic acid, tricholoroacetic acid, salycilic acid and lactic acid. New topical agents such as methimazole, flutamide and cysteamine have also been tried. Physical agents like lasers and dermabrasion have been used. However, the disorder is difficult to treat, particularly in dark-skinned individuals. Tranexamic acid (trans-4-aminomethyl cyclohexane carboxylic acid), as a plasmin inhibitor, has shown promising effects as a melasma treatment. Several forms of tranexamic acid, including oral, topical and localized microinjection forms, have been shown to improve melasma. Although the mechanism of action of tranexamic acid remains unclear, it has been suggested that it inhibits melanin synthesis by interfering with the interaction between melanocytes and keratinocytes. It was also suggested that tranexamic acid can reverse the abnormal dermal changes associated with melasma. Platelet rich plasma (PRP) affects melanogenesis via α-granules which contain many bioactive substances including platelet-derived growth factor (PDGF), transforming growth factor (TGF)-β1, epidermal growth factor (EGF) and fibrinogen. TGF-β1 significantly inhibits melanin synthesis in a concentration-dependent manner via delayed extracellular signalregulated kinase activation. Also, PRP causes increase in skin volume, new