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Photodynamic therapy - PDT
Combination of a photosensitizer and illumination of the lesion with light, resulting in photodamage and subsequent cell death.
PDT is used in the treatment of actinic keratosis, skin cancer, acne, psoriasis.
Water-filtered infrared A has been shown to be associated with reduced pain in comparison to activation with LED light.
Mechanism of action Methyl aminolevulinate and 5-aminolevulinic acid
are antineoplastic agents. After topical application, porphyrins will accumulate
preferentially intracelluarly in the skin lesions. Light activation of accumulated porphyrins leads to a
photochemical reaction causing phototoxicity to the light exposed target cells.
Castano et al. Nature Reviews Cancer 6, 535–545 (July 2006) | doi:10.1038/nrc1894
Treatment 5-aminolevulinic acid (5-
ALA, Metvix®) photosensitizer.
Image 1: Demarcation of the area to be treated
Image 2: Application of 5-ALA cream
Image 3: Directly after application of hydrosun 750 infrared irradiation
Image 4: Four days post-treatment
Indications: Metvix, Galderma
Thin or nonhyperkeratotic, nonpigmented actinic keratoses (AK) of face, scalp when other therapies unacceptable
Primary treatment of superficial and/or nodular basal cell carcinoma (BCC) where surgery is inappropriate
Primary treatment of biopsy proven squamous cell carcinoma (SCC) in situ (Bowen's disease), where surgery is inappropriate
Common light sourcesAktilite Omnilux
Contraindications Morpheaform basal cell carcinoma (BCC) Invasive squamous cell carcionoma (SCC) of the skin Porphyria Peanut oil hypersensitivity
Precautions Avoid direct eye contact; UV therapy, sun exposure; renal,
hepatic impairment Monitor for recurrence every 6-12 months Pregnancy, lactation (within 48 hours), children < 18 yrs AK: previous 5-FU, tretinoin treatment; pigmented, highly
infiltrating, thick (hyperkeratotic), recurrent lesion BCC: recurrent lesion; BCC associated xeroderma
pigmentosum, Gorlin's syndrome, immunosuppressive therapy.
SCC in situ: genital, pigmented, highly infiltrating, recurrent, > 40 mm diameter lesion
Adverse effects Local reaction eg pain, burning, stinging, prickling,
tingling, bleeding skin; eczema Allergic contact dermatitis; swelling; erythema;
itching; oedema; crusting; ulceration; blister; suppuration; infection; peeling
Hypo/hyperpigmentation; rash, headache, nausea, eye pain, irritation, fatigue, dizziness (uncommon)
Method of administration Preparation of the lesions:
Scales and crusts should be removed before administration of Metvix.
All lesion surfaces should be roughened gently. Care should be taken to avoid bleeding. Thereafter, all lesions should be carefully wiped-off
with an ethanol or isopropanol-soaked cotton pad to ascertain degreasing of the skin.
Application of the gel Metvix should be applied to the entire lesion area
using glove protected fingertips or a spatula. Direct contact of Metvix with the eyes or mucous
membrane should be avoided. The gel can be administered to healthy skin around
the lesions, whereas application near the eyes, nostrils, mouth, ears or mucosa should be avoided (keep a distance of 1 cm).
Application of the gel The gel should cover the lesions and approximately 5
mm of the surrounding area with a film of about 1 mm thickness.
The gel should be allowed to dry for approximately 10 minutes, before an occlusive light-tight dressing is placed over the treatment site.
Following 3 hours of incubation, the dressing should be removed and the remnant gel wiped off.
Illumination Immediately after cleaning the lesions, the entire
treatment area should be illuminated with the light source.
During illumination the lamp should be fixed at a distance from the skin surface of 27-30 cm.
The entire treatment area should be illuminated with the hydrosun 750 for 15-20 minutes.
The irradiation time for more sensitive areas can be reduced to 10–15 minutes.
Sessions Actinic keratosis (solar keratosis)
One session. If not completely cleared 12 weeks after initial
treatment, lesions can be treated a second time with an identical regimen.
Basal cell carcinoma and Squamous cell carcinoma in situ (Bowen's disease) Two sessions at weekly intervals; retreat in 3 months if necessary.
Solid basaliomaSolid basalioma prior to
PDT Healing 5 months after second PDT treatment
Fluorescence diagnosis with handheld torch
Dermabrasion
Hobart Case Report - AK ALA 20% solution Australian Customs Pharmaceuticals, Sydney $90 for 5ml Treatment provided by Dr Ian Hoyle, Hobart Treating patients with generalised solar damage:
good results, less pain than when using LED light
Aktinic keratosis
Applying ALA (5-aminolevulinic acid)
Activation of ALA with Hydrosun 750 water-filtered
infrared A lamp
AK nose: day after treatmentHealed completely in 7 days