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Protoporphyrin IX formation after topical application of methyl aminolaevulinate and BF ‐200 aminolaevulinic acid declines with age
Author(s) -
Nissen C.V.,
Philipsen P.A.,
Wulf H.C.
Publication year - 2015
Publication title -
british journal of dermatology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.304
H-Index - 179
eISSN - 1365-2133
pISSN - 0007-0963
DOI - 10.1111/bjd.13923
Subject(s) - protoporphyrin ix , medicine , dermatology , chemistry , organic chemistry , photodynamic therapy
Summary 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 (Pp IX ) from 5‐aminolevulinic acid ( ALA ). A variety of physiological changes in epidermal function occur with increasing age, but no studies have investigated whether Pp IX formation is age‐related. Objectives To investigate a possible relationship between age and Pp IX 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). Pp IX 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 ( BCC s) treated with MAL ‐ PDT . Results Both photosensitizers induced significantly more Pp IX formation in the younger group. Linear regression revealed a significant age‐related decline in Pp IX 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 Pp IX formation. The treatment efficacy of BCC s 3 months after MAL ‐ PDT was higher in young patients ( P = 0·012). Conclusions Pp IX 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.