Efficacy of Iontophoresis-assisted AFL-PDT in Actinic Keratosis

Efficacy of Iontophoresis-assisted Ablative Fractional Laser Photodynamic Therapy With Short Incubation Time for the Treatment of Actinic Keratosis: 12-month Follow-up Results of a Prospective, Randomised, Comparative Trial

Iontophoresis is a transdermal drug-delivery technique that enhances the transport of ionic species across membranes and may have significant benefit for the treatment of actinic keratosis (AK) by ablative fractional laser-primed photodynamic therapy (AFL-PDT).

Photodynamic therapy (PDT) with methyl-aminolevulinate (MAL) is effective in the treatment of actinic keratosis (AK). Many strategies have been studied to improve the production of protoporphyrin IX (PpIX), to improve efficacy of PDT. Pre-treatment of the skin with fractional laser resurfacing is a novel alternative technique to improve the efficacy of PDT for AK. Our previous studies showed that ablative fractional laser-primed PDT (AFL-PDT) offered higher efficacy than conventional MAL-PDT in the treatment of many diseases, such as AK, actinic cheilitis, Bowen's disease and basal cell carcinoma.1-4 Iontophoresis can be another method to improve efficacy of PDT. Iontophoresis is a transdermal drug-delivery technique which uses a mild electric current to enhance the transport of ionic species across membranes. Iontophoresis has been widely used to enhance drug delivery. Mizutani K et al.5 reported 5 AK patients successfully treated with direct-current pulsed iontophoresis-assisted 5-aminolevulinic acid (ALA)-PDT. Boddé HE et al.6 studied iontophoretic transport of ALA quantitatively in vitro and demonstrated enhanced transport of ALA by iontophoresis.

Until now, appropriate incubation time for AFL-PDT has not been elucidated. In our previous study, we investigated the efficacy of AFL-PDT with a short incubation time.7 Although AFL-PDT with a short incubation time (2 h) showed enhanced efficacy than conventional MAL-PDT with the standard incubation time, standard AFL-PDT with 3-h incubation time showed significantly higher efficacy than AFL-PDT with a short incubation time.

The aim of our study was to evaluate efficacy of iontophoresis in AFL-PDT for AK treatment. Consequently, we compared efficacy, recurrence rate, cosmetic outcome and safety between iontophoresis-assisted AFL-PDT with 2-h incubation time and conventional AFL-PDT with 2-h and 3-h incubation times.

Inclusion Criteria:

• Korean patients aged ≥ 18 years who had biopsy-confirmed AK lesions

Exclusion Criteria:

• lactating or pregnant women
• patients with porphyria or a known allergy to any of the constituents of the MAL cream and lidocaine
• patients with systemic disease, history of malignant melanoma, tendency of melasma development or keloid formation, any AK treatment of the area in the previous 4 weeks, or any conditions associated with a risk of poor protocol compliance; and patients on immunosuppressive treatment
• metal-containing device (cardiac pacemaker, orthopaedic implants, gynaecological devices)
• cardiac arrhythmia
• large skin erosion