Melasma – “The Mask of Pregnancy”
Melasma also known as Chloasma or the “Mask of Pregnancy” describes irregular dark pigmentation of facial skin which is likely as a result of a combination of factors including an increase in the female hormones oestrogen and progesterone, cellular hypersensitivity to normal oestrogen levels and exposure to sunlight. Melasma which is on the increase is common in pregnant women, women on oral contraceptives and women on hormone replacement therapy. Other potential causes include Chronic Inflammation, Use of Cosmetics, Phototoxic agents and certain Medicaitons. The characteristic dark patches usually occur on the forehead, apples of the cheeks, jawline, nose and chin. The pigment producing cells known as melanocytes are triggered to produce excessive melanin. The condition may or may not resolve after pregnancy or discontinuing contraceptives or hormone replacement.
Melanocytes are located in the basal layer of the epidermis (outer layer of skin) and make up about 10% of the cells present in this layer of skin. Melanin formation in these cells starts with the formation of the enzyme tyrosinase in a gene deep within the cell. Tyrosinase converts the amino acid known as tyrosine into dopa which is converted to dopaquinone. The dopaquinone then forms either a black-brown pigment known as eumelanin or a yellow-red pigment known as pheomelanin in structures known as melanosomes which are then transferred to epidermal cells on the surface of the skin.
Individuals with melasma must avoid sun exposure to help reduce its appearance. A practical way to do this is by the daily application of a broad spectrum sun sunscreen with an SPF (Sun Protection Factor) of at least 30. In addition to the use of sunscreens, wearing wide brimmed hats as well as large sunglasses also help.
The treatment is aimed at bleaching the patchy discolouration to even out skin tone. A proper bleaching routine helps eliminate excess pools of pigment and prevents the formation of melanin by inactivating tyrosine or interfering with its function. Tyrosine activity may be prevented through a variety of means including providing a false substrate for tyrosinase, stripping tryrosinase of the glucose it requires to function, blocking it from reaching its cell receptors or reducing the factors that stimulate its activity such as hormone treatment and sun exposure.
Effective bleaching agents have a combination of ingredients that work synergistically to produce the desired results. Hydroquinone (HQ) which interferes with tyrosinase activity is the only medically recognized bleaching agent which must be used under the supervision of a doctor. Other ingredients are referred to as lighteners, brighteners or whiteners. Hydroquinone is the most commonly used bleaching agent and it exists in prescription (4%) and non-prescription (2%) strengths. There are two main adverse side effects of hydroquinone use namely skin irritation and ochronosis. Ochronosis is an uncommon side effect that may occur with long term use or in high concentrations (10% and above) where the treated skin area or tissue such as cartilage darkens or becomes bluish-black in colour. Hydroquinone must not be used in pregnancy or by nursing mothers. HQ should be discontinued if darkening is observed. HQ is still used in the United States but has been banned in Europe and South Africa.
Kojic acidis a lightening agent derived from a fungus that is commonly used in the Far East. It inhibits tyrosinase activity and over time, reduces the ability of melanocytes to transfer residual pigment to surface skin cells. Azaleic Acid is a by product of a yeast known as Pityrosporum ovalewhich is also used for the treatment of acne. Azaleic acid acts selectively on overactive melanocytes and does not affect normally pigmented skin thus providing target specific results. Paper Mulberry is derived from a plant extract and is not a skin irritant. It inhibits tyrosinase activity. Mitracarpus Scaber Extract is derived from a tropical plant with harounoside as its active ingredient which is a derivative of HQ. It is more effective, less irritating and is without the risks associated with HQ usage. Bearberry Extract (Arctostaphylos Uva Ursi Extract) is derived from the leaves of the bearberry shrub. It is also a derivative of HQ without the adverse side effects. Dithiaoctanediol acts by preventing the addition of glucose molecules to tyrosinase thus inhibiting its activity. Beta-Carotene is a Vitamin A molecule which acts by blocking tyrosinase receptors on melanocytes. Licorice Extract has glabridin as its main ingredient which is capable of preventing tyrosinase activation and helps reduce inflammation. Gluconic Acid is a chelating agent that binds copper molecules that are required for activating tyrosinase.
Vitamin C in its various forms such as L-ascorbic acid, sodium ascorbyl phosphate and magnesium ascorbyl phosphate is capable of inhibiting melanin production. Exfoliation can remove discoloured skin cells thus revealing clearer skin and this can be achieved through the use of agents such as Alpha Hydroxy acids, Beta Hydroxy acids, Retinoids, Papain (from Papaya) and sutilains.
For the treatment of melisma which involves the use of a bleaching agent, a sunscreen must be worn. There are several combination bleaching agents both prescription and non-prescription available for use. There are also specialty treatments that may be performed by your doctor such as TCA peels and Microdermabrasion. Certain supplements including high dose Vitamin C (1,000mg of Ester C), Essential Fatty Acids and MSM are thought to help improve this condition.
It is important to contact a doctor when melasma is first noticed so as to outline a suitable treatment program. Patience is required when treating melasma and you should not expect results overnight. Adhere to a regular program and when the desired results have been achieved, stop the bleaching creams but continue to use sun protection. There is no cure for melasma and results vary. It may recur in some individuals while it may never come back in others.
The most efficient treatment for Melasma in my opinion and based on Clinical Experience is the ZO Multi-therapy Hydroquinone System (By Zein Obagi MD).
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