Skin Lightening Agents

Chapter 15 Skin Lightening Agents



Marta I. Rendon, Jorge I. Gaviria



INTRODUCTION


Hyperpigmentation is a common skin problem that is particularly prevalent in middle-aged and elderly individuals. It is cosmetically important and can greatly detract from both appearance and quality of life, particularly in cultures where smooth skin is valued as a sign of health or in cultures that are beauty conscious. Hyperpigmented skin lesions may be postinflammatory as a sequel to acne, trauma, chemical peels, or laser therapy. Exogenous causes, particularly ultraviolet (UV) light exposure, are a common factor in pigmentary abnormalities such as melasma, solar lentigines, and ephelides (Fig. 15.1). Exposure to certain drugs and chemicals as well as the existence of certain disease states can result in hyperpigmentation (Box 15.1).


image

Fig. 15.1 The typical appearance of melasma with reticulated hyperpigmented plaques. (A) Before cosmeceutical treatment. (B) Eight weeks after cosmeceutical treatment



Box 15.1 Acquired hyperpigmentation



SKIN DISEASES AND CONDITIONS




image Melasma


image Riehl’s melanosis


image Poikiloderma of Civatte


image Erythromelanosis follicularis


image Linea fusca


image Postinflammatory hyperpigmentation



EXOGENOUS CAUSES




image Ultraviolet exposure (e.g. melasma, solar lentigines, ephelides)


image Photosensitizing agents (e.g. berloque dermatitis due to bergamot oil, furocoumarins)


image Drugs (e.g. estrogens, tetracyclines, amiodarone, phenytoin, phenothiazines, sulfonamides)


image Cosmetics



OTHER CAUSES




image Pregnancy


image Liver disease


image Addison’s disease


image Hemochromatosis


image Pituitary tumors


The treatment of acquired hyperpigmentation has traditionally been challenging and frequently discouraging. Many of the agents that have been used cause skin irritation, require many months of regular use before results are apparent, or are only partly effective. Patient compliance with therapy must be strict. Sun avoidance and the religious use of a high sun protection factor (SPF) sunblock are mandatory for successful treatment.



SKIN LIGHTENING COSMECEUTICALS


Multiple depigmenting cosmeceuticals are currently available, although published clinical evidence to support their effectiveness is lacking. These skin lightening compounds work by removing undesired pigment by acting at one or more steps in the pigmentation process (Box 15.2). Since tyrosinase is the rate-limiting enzyme for melanin biosynthesis, many of the cosmeceuticals for skin lightening exert their effect on this enzyme.



Box 15.2 Depigmenting agents and reported effect on the melanin synthetic pathway



BEFORE MELANIN SYNTHESIS




image Tyrosinase transcription:


Tretinoin


DURING MELANIN SYNTHESIS




image Tyrosinase inhibition:


Hydroquinone

4-Hydroxyanisole

4-S-CAP and derivatives

Arbutin

Aloesin

Azelaic acid

Kojic acid

Emblica

Tyrostat

image Peroxidase inhibition:


Phenols

image Product reduction and ROS scavengers:


Ascorbic acid

Ascorbic acid palmitate


AFTER MELANIN SYNTHESIS




image Tyrosinase degradation:


Linoleic acid

α-Linolenic acid

image Inhibition of melanosome transfer:


Serine protease inhibitors

Lecthins and neoglycoproteins

Soybean/milk extracts

Niacinamide

image Skin turnover acceleration:


Glycolic acid

Lactic acid

Linoleic acid

Liquiritin

Retinoic acid

Helix aspersa Müller

4-S-CAP, 4-S-cystaminylphenol.


Modified from Briganti S, Camera E, Picardo M 2003 Chemical and instrumental approaches to treat hyperpigmentation. Pigment Cell Research 16:1–11.



• Hydroquinone


For many years, the phenolic compound hydroquinone has been the most widely and successfully used skin lightening agent for the treatment of melasma, postinflammatory hyperpigmentation, and other disorders of hyperpigmentation (Fig. 15.2). Hydroquinone occurs naturally in many plants as well as in coffee, tea, beer, and wine. Hydroquinone depigments skin by inhibiting the conversion of tyrosine to melanin. It has been shown to decrease tyrosinase activity by 90%. It may also inhibit DNA and RNA synthesis, as well as degrade melanosomes.


image

Fig. 15.2 (A) The appearance of facial melasma before treatment. (B) Improvement in hyperpigmentation following hydroquinone therapy (8 weeks after treatment)


In the US, hydroquinone is available over the counter (OTC) in strengths up to 2%. Most prescription strength hydroquinone formulations contain 3–4%, but concentrations as high as 10% may be available through compounding pharmacies.


Also, several new combination agents are now available in the US. A prescription drug containing 4% hydroquinone, tretinoin, and a low-potency fluorinated steroid, fluocinolone acetonide, is effective and safe in the treatment of melasma. Other combination products contain glycolic acid, vitamin C, and/or retinol to function as penetration enhancers for the hydroquinone active.


Hydroquinone is generally considered safe. Common side effects are skin irritation or contact dermatitis, which can be treated with topical steroids. A rare but serious side effect of hydroquinone is the development of exogenous ochronosis, a sooty hyperpigmentation in the treatment area, which may be difficult to reverse. Exogenous ochronosis appears to be prevalent among darker complected individuals when hydroquinone is used at high concentrations or for prolonged periods even at low concentrations.

Related posts:

Default ThumbnailDyspigmented Skin Cosmeceuticals and the Practice of Dermatology Cosmeceuticals: Function and the Skin Barrier Exfoliants, Moisturizers and More: AHAs, BHAs, and PHAs Sunscreens Evaluating Cosmeceutical Efficiency

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Mar 12, 2016 | Posted by in General Surgery | Comments Off on Skin Lightening Agents

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