Publications (3)3.51 Total impact
Contact Dermatitis 08/2011; 65(2):117-8. · 3.51 Impact Factor
Article: A review of pain experienced during topical photodynamic therapy--our experience in Dundee.[show abstract] [hide abstract]
ABSTRACT: Topical photodynamic therapy (PDT) using 5-aminolaevulinic acid (ALA) and its methylated ester, methyl aminolevulinate (MAL) is widely used to treat superficial non-melanoma skin cancer (NMSC). It has been proposed that ALA PDT is more painful than MAL PDT. The aim of this paper was to compare pain scores of MAL PDT with ALA PDT in our patients and to analyse the relationship between various parameters and pain during PDT. We retrospectively reviewed case notes and electronic records for all patients with superficial NMSC treated with PDT from June 2007 to March 2009. On univariate analysis of patients with single lesions only, we observed no association between pain and lesion diameter or pro-drug or dose or diagnosis. Pre-treatment PpIX fluorescence was significantly associated with pain. However on univariate analysis of all patients (whether single or multiple lesions) treated with PDT, MAL was associated with significantly less pain than ALA. When all the recorded variables were taken into account (multivariate analysis), diagnosis, pre-treatment PpIX fluorescence and lesion diameter were associated with pain. Our data lends some support to previous published reports suggesting that the MAL PDT regime is less painful than that for ALA PDT. However, PDT pain is multifactorial and choice of photosensitiser is probably not a major pain determining factor. A prospective randomised study, with the same incubation periods for each pro-drug, is needed to definitively answer the question as to whether or not MAL PDT causes less pain than ALA PDT.Photodiagnosis and photodynamic therapy 03/2011; 8(1):53-7.
Article: Cutaneous expression of cytochrome P450 CYP2S1: individuality in regulation by therapeutic agents for psoriasis and other skin diseases[show abstract] [hide abstract]
ABSTRACT: Background Treatment of common skin diseases such as psoriasis is complicated by differences between individuals in response to topical drug treatment and photochemo-therapy. Individuality in hepatic expression of drug-metabolising enzymes is an important determinant of systemic drug handling; we investigated whether similar variation in cutaneous gene expression contributes to individuality in response to topical therapies. Methods We used quantitative real-time RT-PCR to demonstrate the expression in skin of a recently identified cytochrome P450, CYP2S1, in healthy volunteers (n=27) and patients with psoriasis (n=29). We also investigated regulation of CYP2S1 by ultraviolet radiation, psoralen-ultraviolet A (PUVA), and topical drugs used to treat psoriasis. Findings We found that CYP2S1 is expressed in skin and showed pronounced individuality in constitutive expression of the enzyme and its induction after ultraviolet irradiation or topical drug treatment. Cutaneous expression of CYP2S1 was induced by ultraviolet radiation, PUVA, coal tar, and all-trans retinoic acid; expression was significantly higher in lesional psoriatic skin than in adjacent non-lesional skin (geometric mean 3·38 [95% CI 2·64–4·34] times higher; p<0·0001), which implies that topical drugs are differentially metabolised in psoriatic plaque and non-lesional skin. We showed that all-trans retinoic acid is metabolised by CYP2S1, which has higher cutaneous expression than CYP26, previously described as the specific cutaneous P450 retinoic-acid-metabolising enzyme. Interpretation These findings increase our understanding of the interaction between therapeutic agents and the skin and suggest a functional role for CYP2S1 in the metabolism of topical drugs and in mediating the response to photochemotherapy in psoriasis. Medical Research Council (grant reference G0000281) Chief Scientist Office