Protoporphyrin IX formation after topical application of methyl aminolaevulinate and BF-200 aminolaevulinic acid declines with age

C. V. Nissen*, P. A. Philipsen, H. C. Wulf

*Corresponding author af dette arbejde

Publikation: Bidrag til tidsskriftTidsskriftartikelForskningpeer review

16 Citationer (Scopus)

Abstract

Background Topical photodynamic therapy (PDT) is a popular treatment modality in dermatology. The effect of PDT in epidermal cells depends on formation of protoporphyrin IX (PpIX) from 5-aminolevulinic acid (ALA). A variety of physiological changes in epidermal function occur with increasing age, but no studies have investigated whether PpIX formation is age-related. Objectives To investigate a possible relationship between age and PpIX formation. Methods Methyl aminolaevulinate cream (MAL) and 5-ALA gel (BF-200 ALA) were applied to two identical fields on the forearm of 30 healthy volunteers for 24 h. The volunteers were divided into two age groups: a young group under 55 years (range 18-54) and an older group over 55 years (range 65-85). PpIX formation was measured noninvasively every hour from 1-5 h, and after 18, 21 and 24 h. Skin phototype, stratum corneum hydration and ultraviolet (UV) damage were also assessed. Treatment efficacy in relation to age was evaluated in 100 basal cell carcinomas (BCCs) treated with MAL-PDT. Results Both photosensitizers induced significantly more PpIX formation in the younger group. Linear regression revealed a significant age-related decline in PpIX formation after the standard application time of 3 h (P < 0·001 for both treatments). Skin phototype, stratum corneum hydration and UV damage were not associated with PpIX formation. The treatment efficacy of BCCs 3 months after MAL-PDT was higher in young patients (P = 0·012). Conclusions PpIX formation in human skin declines with age. No explanation could be attributed to skin phototype, stratum corneum hydration or UV damage. The consequence might be reduced efficacy of PDT in the elderly. What's already known about this topic? Topical photodynamic therapy (PDT) is based on protoporphyrin IX (PpIX) formation in epidermal cells. PpIX formation varies greatly among individuals. The physiological properties of the epidermis change with increasing age, yet no studies have investigated whether PpIX formation is age related. What does this study add? PpIX formation in human skin declines with age after topical application of two commercially available photosensitizers. No explanation could be attributed to skin phototype, stratum corneum hydration or ultraviolet damage of the skin. Low PpIX formation in the elderly might result in inferior treatment efficacy of PDT.

OriginalsprogEngelsk
TidsskriftBritish Journal of Dermatology
Vol/bind173
Udgave nummer3
Sider (fra-til)760-766
Antal sider7
ISSN0007-0963
DOI
StatusUdgivet - 1 sep. 2015

Bibliografisk note

Publisher Copyright:
© 2015 British Association of Dermatologists.

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