ARTICLE | dermatology | Study


Table 1 Proposed PDT treatment regimens in published studies Topical agent Light source


Time of illumination Pollock et al (2004)17


Hongcharu et al (2000)11 Itoh et al (2000)43 Itoh et al (2001)14


Hörfelt et al (2006)36 Wiegell et al (2006)18 Wiegell et al (2006)37 Mavillia et al (2007)41 Haedersdal et al (2008)4 Yeung et al (2007)40 ALA


ALA ALA ALA MAL


MAL Diode laser


Broadband light Laser


Halogen lamp Non-coherent red


light (Aktilite CL 128 PhotoCure ASA)


Red light, (Aktilite CL Two sessions, 2 weeks apart 9 minutes, total dose 37 J/cm2 128 PhotoCure ASA)


MAL or ALA, Red light, (Aktilite CL Once 3h, occlusion 128 PhotoCure ASA)


MAL 4%, 1.5 hour,


no occlusion


MAL 16%, LPDL 3 hour


occlusion MAL


Broadband light Three sessions every 2 weeks 595 nm, 7.5 J/cm2 Four sessions every 3 weeks 530–750 nm ALA=aminolaevulinic acid; LPDL=long-pulsed dye laser ; MAL=methyl aminolaevulinic acid; PDT=photodynamic therapy and especially for those who develop bacterial


resistance or an adverse event with traditional acne treatments. the strength of evidence with regard to the use of Pdt for acne varies, and includes results from randomised controlled, investigator-blinded trials, and case series, as well as isolated case reports. an optimal treatment regimen has not yet been defined, and existing studies have identified differing treatment protocols with regard to the light source used, the treatment schedule, parameters, and the concentration of the photosensitising agent (Table 1).


Photodynamic therapy for acne vulgaris It is well known that acne often improves significantly after exposure to sunlight or artificially produced ultraviolet (UV) radiation6


. In 1987, meffert et al reported


improvement of acne and seborrhoea on the face and back in male volunteers after 17 radiations with a cumulative dose of 22 kJ/cm2 emit visible light7


, using halogen lamps that . the degree of improvement was


comparable to that observed with UVa. this effect may be attributed to an endogenous photodynamic reaction of porphyrins produced by P. acnes, singlet oxygen production and bacterial killing, whereas UVa irradiation induces the production of superoxide anions, membrane damage and single strand breaks in dNa (deoxyribonucleic acid)8


. In 1990, Kennedy and colleagues introduced the use of


topical ala as a photosensitising agent for the treatment of cutaneous conditions by Pdt9


44 ❚ . the rationale for the


use of ala–Pdt in the treatment of acne vulgaris was provided by two groups of investigators. divaris et al demonstrated that intraperitoneal injection of ala in


July 2011 | prime-journal.com In 1990,


kennedy and colleagues introduced the use of topical ALA as a photosensitising agent for the treatment of cutaneous conditions by PDT.


mice resulted in preferential accumulation of porphyrin in the sebaceous glands10


, 10 ms, 10 mm spot size, dynamic cooling device 30/20, slightly overlapping pulses, two passes


Red light (Aktilite CL Three sessions at week 0, 128, Galderma)


week 1, week 4 9 minutes, 34 mW/cm2 , 37 J/cm2 In right/left areas: 10–20 J/cm2


Once or multiple Once Once


Parameters of use


10 minutes, once every week 635nm, 25mW/cm2 for 3 weeks


, 15 J/cm2


550–700 nm, 17mW/cm2 635 nm, 5 J/cm2


, 13 J/cm2 600–700 nm, fluence rate 17 mW/cm2 Two sessions, 2 weeks apart Average 635 nm, 37 J/cm2 , 13 J/cm2


. Subsequent exposure to light


destroyed the sebaceous cells, and caused reactive changes in keratinocytes10


. It was not until 2000 that


Hongcharu and colleagues studied ala–Pdt with high-dose broadband red light in 22 subjects with acne11


.


the authors showed an improvement of inflammatory acne, reduction in sebum excretion rates, and suppression of bacterial fluorescence associated with colonisation of P. acnes in sebaceous follicles, and in the damage done to sebaceous glands. In this study, skin biopsies taken from patients 20 weeks after four Pdt sessions showed a marked or complete sebaceous gland atrophy. on the other hand, the sebaceous glands were 83% of the pre- treatment size at 17 weeks in patients who received a single session of Pdt11


. It should be noted that total sebaceous gland


destruction is not desirable, since sebaceous lipids provide intrinsic antimicrobial activity, are anti-inflammatory and deliver vitamin e to the upper layers of the skin12


; therefore, less aggressive therapeutic


parameters may provide clinical efficacy while maintaining anatomical functionality13


; 635 nm red light17, 18 ; IPl19 . other Pdt studies


followed, examining a plethora of light sources used for photoactivation, including 600–700 nm halogen14 light15, 16 Pdl)20


. ; blue ; and long-pulsed Pdl (lP


. mal (3-hour incubation time) rather than ala was used by Wiegell and Wulf as a photosensitiser18


Mode of action In general, three components are required for Pdt — a photosensitiser, light and oxygen. Porphyrin Pdt (versus psoralen-mediated Pdt) is oxygen dependent. Pdt is a two-step therapeutic technique involving the topical


Page 1  |  Page 2  |  Page 3  |  Page 4  |  Page 5  |  Page 6  |  Page 7  |  Page 8  |  Page 9  |  Page 10  |  Page 11  |  Page 12  |  Page 13  |  Page 14  |  Page 15  |  Page 16  |  Page 17  |  Page 18  |  Page 19  |  Page 20  |  Page 21  |  Page 22  |  Page 23  |  Page 24  |  Page 25  |  Page 26  |  Page 27  |  Page 28  |  Page 29  |  Page 30  |  Page 31  |  Page 32  |  Page 33  |  Page 34  |  Page 35  |  Page 36  |  Page 37  |  Page 38  |  Page 39  |  Page 40  |  Page 41  |  Page 42  |  Page 43  |  Page 44  |  Page 45  |  Page 46  |  Page 47  |  Page 48  |  Page 49  |  Page 50  |  Page 51  |  Page 52  |  Page 53  |  Page 54  |  Page 55  |  Page 56  |  Page 57  |  Page 58  |  Page 59  |  Page 60  |  Page 61  |  Page 62  |  Page 63  |  Page 64  |  Page 65  |  Page 66  |  Page 67  |  Page 68  |  Page 69  |  Page 70  |  Page 71  |  Page 72  |  Page 73  |  Page 74  |  Page 75  |  Page 76  |  Page 77  |  Page 78  |  Page 79  |  Page 80  |  Page 81  |  Page 82  |  Page 83  |  Page 84