Skin pigmentation hydroquinone

Palumbo A, d Ischia M, Misuraca M, Prota G (1992). Skin Pigmentation by Hydroquinone A Chemical and Biochemical Insight. Pigment Cell Res 2 299... 

The aromatic compound hydroquinone is well known to dermatologists as a drug to treat skin pigmentation, and has been used clinically [84-86]. However, hydroquinone is very easily discoloured to black [87]. This is because hydroquinone [CeH4(OH)2] is easily oxidized to quinone (C6H4O2) as follows ... 

Hydroquinone in a 2 percent solution is used in many skin-lightening creams and gels to remove freckles, age spots, and other hyper-pigmented areas of the skin. 

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. 

The incidence of adverse effects with hydroquinone increases in proportion to its concentration. A relatively common side effect is local irritation, which may actually exacerbate the discoloration of the skin being treated. Allergic contact dermatitis occurs less commonly. A rare but more serious complication is exogenous ochronosis, in which a yellow-brown pigment deposited in the dermis results in blue-black pigmentation of the skin that may be permanent. 

Clarys P, Barel A. Efficacy of topical treatment of pigmentation skin disorders with plant hydroquinone glucosides as assessed by quantitative color analysis. J Dermatol 1998 25(6) 412-14. 

Skin types III-VI Hydroquinone 4-8% cream Dally/twice dally starting 6 weeks prior to peel Reduce background pigmentation and the risk of PIH... 

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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