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Hyperpigmentation induced by topical 5-aminolaevulinic acid plus visible light
Giuseppe Monfrecola1, Enrico Maria Procaccini, Donatella D'Onofrio
1Department of Dermatology, University Federico II, Via S. Pansini 5, 80131 Napoli, Italy. monfreco@unina.it
Journal of Photochemistry and Photobiology. B, Biology
|December 7, 2002
Summary
Topical 5-aminolaevulinic acid (ALA) with visible light irradiation penetrates intact skin, activating melanocytes. This ALA-PDT treatment induces skin pigmentation, showing potential for hypopigmentation disorders.
Area of Science:
- Dermatology
- Photomedicine
- Skin Biology
Background:
- Photodynamic therapy (PDT) using 5-aminolaevulinic acid (ALA) is an established treatment for superficial skin cancers.
- ALA-PDT has shown promise for conditions like warts, condylomata, and psoriasis.
Purpose of the Study:
- To evaluate the effects of topical ALA and visible light irradiation on intact human skin.
- To assess ALA penetration and its impact on skin physiology and pigmentation.
Main Methods:
- Healthy volunteers (skin types III-IV) received topical ALA (5-20%) or vehicle with occlusive dressing.
- Treated areas were irradiated with 40 J/cm(2) visible light.
- Skin penetration, clinical changes, colorimetry, and microscopy (histopathology, immunohistochemistry, electron microscopy) were used for evaluation.
Main Results:
- ALA penetrated intact skin, forming Protoporphyrin IX (PpIX), the active photosensitizer.
- ALA plus irradiation caused immediate erythema/swelling and subsequent hyperpigmentation.
- Histological analysis revealed a significant increase and activation of melanocytes.
Conclusions:
- Topical ALA followed by visible light irradiation induces a pigmentation response in healthy skin (types III-IV).
- The observed melanocytic activation suggests potential therapeutic applications for hypopigmentation disorders.