Atopic Dermatitis: a Short Summary
Hydroquinone is the gold standard in the treatment of hyperpigmentary disorders but there are 3. things to bear in mind:
-a concentration of 4% or more is needed to be effective.
-because of a higher concecntration, side effects such as exogenous ochronosis are a risk. Because of a lack of evidence pertaining to long term toxicology issues, the substance is banned in Europe for use as an over-the-counter (OTC) drug.
-hydroquinone is a non-natural substance which is part of the phenol molecules. It is toxic to pigment cells (melanocytes) and its effects can be irreversible.
- Cysteamine is a non melanocytoxic molecule comparable in this sense to others such as arbutin and kojic acid.
- It has been known for its depigmeting effect for over 5 decades and in the early 2000’s in was shown by an Australian team of researchers to exert its effect by inhibiting tyrosinase, a key enzyme involved in the early phases of melanin synthesis.
- The problem which is now solved with a new technology was that the molecule was unstable and malodorous when compiled in topical preparations
1. Hydroquinone 4% was compared with Cysteamine Cream (CC). 6 subjects were treated with Hydroquinone (HQ) on one ear and CC on the other. Another 6 were treated with the vehicle alone. Frequency of application: once daily for 10 days
-a considerable depigmentation is already visible to the naked eye.
-colorimetry shows that the degree of pigmentation is lower in CC than the vehicle. There is no staistically significant difference between CC and HQ.
-biopsies of the skin show similar results when the quantity of melanin is measured (spectrophotometric analysis)
2. 10 Individuals with dark skin (phototype IV – VI of Fitzpatrick) are treated every evening for 3 weeks.
A close up picture of the skin (dermoscopy) shows uniform depigmentation
Confirmation of visual results is done with colorimetry (statistically significant: p smaller than 0.05 according to student’s test)
3. 40 subjects with melasma are treated nightly for 6 weeks.
A close up picture of the skin (dermoscopy) shows uniform depigmentation
Confirmation of visual results is done with colorimetry (statistically significant: p smaller than 0.05 according to student’s test)
Irritation is observed in 2 patients which is reveresed when the treatment is stopped.
A notice to users: because of a dilation of blood vessels, a heat sensation may be felt upon applying the product the first time.
4. Depigmentation is also seen in the 35 patients treated for post-inflammatory hyperpigmentation (same treatment regimen as “3”).
However there is no comparison with the natural spontaneously favorable evolution of post inflammatatory hyperpigmentation.
5. To conclude Cysteamine Cream is effective, safe and user-friendly and can be considered a treatment option for the treatment of hyperpigmentary skin conditions.
adapted for the online version
Hsu C. Cysteamine Cream as a new depigmenting product. 9th Asian Dermatological Congress (ADC) 13 – Hong Kong, SAR
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