ASLMS / FDA Session Summary
october 30, 2018
Dr. Kachiu C. Lee,
Director of Government
Communication and Education
ASLMS has been collaborating with the FDA for years to provide educational meetings at the FDA. The goal of the meetings is to provide an unbiased educational forum and two-way exchange of information about lasers and related technology and the challenges of bringing technology forward.
On October 30, 2018, Merete Haedersdal, MD, PhD, DMSc and Dieter Manstein, MD, PHD met with the FDA to discuss laser-assisted photodynamic therapy and fractionated laser technologies.
Dr. Merete Haedersdal’s talk, titled “Laser-assisted Photodynamic Therapy," started by discussing structure of the skin, and the role of the stratum corneum as a barrier to drug delivery. Using lasers to create channels opens up a realm of possibilities to enhanced drug penetration of topical treatment regimens. Dr. Haedersdal presented literature on the different diffusion patterns of hydrophilic drugs, such as methotrexate and 5-fluorouracil, compared to the lipophilic drugs, such as diclofenac and ingenol mebutate. Clinical applications of laser assisted drug delivery include alopecia, melasma, onychomycosis, local anesthesia, rejuvenation, scars, and skin malignancies. With specific regards to PDT, she addressed current and laser-assisted methods of enhanced penetration of the medication, including microdermabrasion and curettage of hypertrophic lesions compared to non-ablative and ablative fractional therapy (AFXL). Finally, Dr. Haedersdal presented the literature for laser- assisted drug delivery of photodynamic therapy using AFXL channels to deliver MAL, and lasers assisted delivery of 5-FU and ingenol mebutate for AKs and Bowen’s disease. She also discussed Dr. Jill Waibel’s research on laser assisted delivery of triamcinolone and 5-FU for treatment of scars.
Dr. Dieter Manstein’s talk was titled “Fractionated Laser Technologies." Dr. Manstein reviewed the thermal remodeling techniques used in dermatology, including non-ablative laser resurfacing, ablative laser resurfacing, non-ablative fractional photothermolysis, and ablative fractional photothermolysis. He discussed the histologic effects of fractionated laser treatment on pigment, collagen (dermal remodeling), and vasculature (random coagulation of small blood vessels). Dr. Manstein encouraged the audience to think of both the reduction and increase effects of this technology. For example, fractionated laser treatments can cause both a reduction and increase in pigment, collagen (reduction of collagen with hypertrophic burn scar treatments, increase in collagen for acne scars), and vascularity. There was extensive discussion on the exposure parameters of this technology, including individual lesion geometry (energy per MTZ, size of individual MTZ, pulse duration and peak power) and average thermal load (fluence, MTZ density, scan duration and interval, number of passes, and cooling/heat removal).
At the conclusion of both talks, there was lively discussion between our experts, Drs. Haedersdal and Manstein, regarding fractional lasers, how much tissue sparing is necessary to consider the treatment “fractional”, and bulk heating. There was also discussion on microdermabrasion and its use with PDT.