The New Straits Times, February 26, 1998
Q: Hydroquinone creams were highlighted recently as adversely affecting the skin. Can you explain the use of these products and their effects?
A: The recent statement by the Minister of Health against beauticians prescribing skin bleaching products containing more than two per cent hydroquinone follows the world-wide concerns about the use of such products (NST, Feb 2).
The move to create awareness about the adverse effects caused by these products was needed considering that the demand for them has increased so much that they are now illegally manufactured here to meet demand.
Although they serve a cosmetic function in lightening skin colour, it must be known that these products are drugs and have potential toxicity if used without advice from doctors.
Originally, a number of topical agents have been used in skin-bleaching preparations. These included hydroquinone, the monobenzyl and monomethyl esters of hydroquinone, ammoniated mercury, ascorbic acid and peroxides.
Unfortunately, most of these agents have limited clinical use because of their effects and resultant complications. For example, mercury compounds have been used with varying success to lighten skin pigment. The mercury ions are thought to inhibit the synthesis of melanin, a black pigment responsible for darkening the skin.
However, the use of mercury is banned in many countries because of percutaneous absorption and potential nephrotoxicity.
On the other hand, the monobenzyl and monomethyl esters of hydroquinone were used initially in the late 1930s to bleach skin. Due to its unpredictable actions and cosmetic disasters, it is now being used exclusively on people with extensive vitiligo.
Under normal physiology, the skin colour is contributed by melanocytes in the basal layer of the epidermis, which produce pigment granules called melanosomes. These pigment granules contain complex protein called melanin, a brown-black pigment.
Melanocytes can be viewed as tiny one-celled glands with long projections to pass pigment particles into the keratinocytes, which synthesise skin keratin. As keratinocytes migrate upward, they carry the pigment with them and deposit it on the skin surface as they die.
Melanocytes are also present in the hair bulb cells and pass pigment granules on to the hair. Melanin is the most efficient sun screen available. It prevents damaging ultraviolet rays from the sun from entering deeper parts of the skin. Solar radiation also stimulates melanocytes to provide more melanin, resulting in gradual skin darkening or a tan.
Here, the Drug Control Authority has approved the use of six skin bleaching products containing hydroquinone in concentrations of two per cent for over-the-counter use while four per cent concentrations are allowed for professional uses only.
These approved products of hydroquinone are Eldopaque Forte (four per cent), Eldopague (two percent), Eldoquine Forte (four per cent), Solaquine (two per cent, Solaguine Forte (four per cent) and Esoterica F (two per cent).
As a comparison with other countries like Nigeria and other African nations, products containing more than two per cent hydroquinone are banned as they cause irreversible hyperpigmentation.
Accordingly, these products are used to treat hyperpigmentation. This condition is described as an unusually pronounced darkening of body tissues caused by excessive deposition of the pigment melanin.
Although hyperpigmentation can be considered to be less important in medical practice, it can, however, be a source of cosmetic disability and distress if it appears on the face. Under normal circumstance, these products do not completely remove the hyperpigmentation but are intended to lighten limited areas of the hyperpigmented skin.
They are recommended for brown-coloured areas of the face. An effective product would normally produce changes between two and three months.
When beginning treatment on hydroquionone, melanin excretion may temporarily increase. A decrease in skin colour usually becomes noticeable in about four weeks. However, the time of onset varies from three weeks to three months. Depigmentation lasts from two to six months, but it reversible.
Darker lesions repigment faster than lighter lesions. Because the ability of the sun to darken lesions is greater than that of hydroquinone to lighten them, strict avoidance of sunlight is important.
The effectiveness of hydroquinone varies among patients. In a US study, hydroquinone two per cent and five per cent creams were applied on the hyperpigmented skin of 56 patients with 12 per cent of the patients being black.
Hydroquinone cream was applied twice daily and the treatment was continued for three months. Hydroquinone was effective as a depigmenting agent in 44 of the cases. The use of hydroquinone five per cent cream was accompanied by adverse effects, mainly irritation.
However, at the lower concentration (two per cent cream), the drug appeared to be equally effective therapeutically with fewer irritant reactions. From the result, it seems that hydroquinone is best on lighter skin and on lighter lesions.
On blacks, the response to hydroquinone depended on the amount of pigment present. The earlier it is used to treat minor skin blemishes, the more likely the results will be satisfactory. When depigmentation does occur, melanin production is reduced by about 50 per cent.
Side effects of topical hydroquinone are mild when used in low concentrations. Tingling or burning on application and subsequent erythema and inflammation were observed in eight per cent of patients using a two per cent concentration and 32 per cent of patients using a five per cent hydroquinone concentration.
Higher concentrations frequently irritate the skin and, if used for prolonged periods, cause disfiguring effects including epidermal thickening, ochronosis-like pigmentation and yellowish papules.
In some cases, lesions become slightly darker before fading. Reversible brown discoloration of nails has been reported occasionally when application of two per cent hydroquinone is used on the back of the hand. The discoloration is probably caused by formation hydroquinone oxidation products.
Hydroquinone is easily oxidised in the presence of light and air. Any discoloration or darkening of the cream is an indication of deterioration in the strength of available hydroquinone.
If hydroquinone is accidentally ingested, it seldom produces serious systemic toxicity. However, oral ingestion of between 5g and 15g doses has produced convulsions and hemolytic anaemia.
Because of lack of safety data, it is not recommended for children under 12, except under a physician's supervision.
If no improvement is seen within three months, its use should be discontinued.
