Hydroquinone hyperpigmentation treatment

Azelaic acid is a naturally occurring dicarboxyl-ic acid (1,7-heptanedicarboxylic acid) that has demonstrated beneficial therapeutic effects in the treatment of acne and several disorders of hyperpigmentation [48]. There are minimal effects on normally pigmented human skin, freckles, senile lentigines, and nevi. The cytotoxic and antiproliferative effects of azelaic acid may be mediated via inhibition of mitochondrial ox-idoreductase activity and DNA synthesis. Disturbance of tyrosinase synthesis by azelaic acid may also influence its therapeutic effects. Azelaic acid can be used as a hypopigmenting agent in patients sensitive to hydroquinone. 

Hydroquinone is used as a photographic developer (with black-and-white film), a dye intermediate, a stabilizer in paints, varnishes, motor fuels and oils, an antioxidant for fats and oils, an inhibitor of polymerization and in the treatment of skin hyperpigmentation (Lewis, 1993). 

Exposure to hydroquinone may occur during its production, its use as an inhibitor, antioxidant and intermediate in the production of dyes, paints, motor fuels and oils, and in black-and-white photographic processing. Hydroquinone occurs naturally in certain plant species. It is used as a topical treatment for skin hyperpigmentation. 

The histological features of melasma and chloasma are discussed elsewhere in this book. The standard recommendations for treatment often only mention topical applications of tretinoin, hydroquinone and other tyrosinase inhibitors corticosteroids and peels are considered as a last resort because of their potential to turn melasma into post-inflammatory hyperpigmentation (PIH). Conventional peels require conscientious pre-peel preparation to avoid this danger. Easy TCA (ETCA), in combination with appropriate post-peel care, can be used to treat melasma without the constraints of pre-peel preparation (Eigures 16.1-16.5). 

In addition to the 16 sunscreens approved in the United States, there are 2 non-sun-screen topical agents that are approved for the treatment of conditions related to photo-induced skin damage. These are tretinoin and hydroquinone. Both are prescription products. Tretinoin is approved as an adjunctive treatment for "mitigation of fine wrinkles, mottled hyperpigmentation, and tactile roughness of facial skin." Hydroquinone has been marketed for decades for bleaching of hy-perpigmented skin conditions. 

Kojic acid (5-hydroxy-4 pyran 4-1-2 methyl) is a fungal derivative which inactivates tyrosinase via chelation of copper. Concentrations range from 2% to 4%. It can be used for monotherapy or in combination with retinoids or other cosmeceutical products such as glycolic acid. Compared to hydroquinone, these kojic acid formulations usually show less efficacy however, they may be effective in patients who do not tolerate hydroquinone. In addition, they can be used as maintenance therapies for treatment of hyperpigmentation following 4-6 months of hydroquinone treatment. Use of kojic acid has been associated with contact dermatitis in sensitized individuals, however [41 3]. 

Cook-Bolden FE, Hamdton SF (2008) An open-label study of the efficacy and tolerability of microencapsulated hydroquinone 4% and retinol 0.15% with antioxidants for the treatment of hyperpigmentation. Cutis 81 365-371... 

Cook-Bolden FE (2004) The efficacy and tolerability of a combination cream containing 4% hydroquinone in the treatment of postinflammatory hyperpigmentation in skin types IV-VI. J Cosmet Dermatol 17(3) 149-155... 

If hyperpigmentation occurs hydroquinone 4% or higher is the mainstay of treatment. Once the skin is sufficiently healed, tretinoin can be added to increase the bleaching effect. Commercial or compounded formulations that include these agents and a topical steroid are also useful. Patients should be advised to use sunscreens and avoid unnecessary sun exposure to the peeled areas as this can prevent further pigment changes and lessen the duration of the darker areas. Also, patients using birth... 

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