ALA-PDT fast, effective

November 1, 2005

ALA-PDT, used in combination with laser or light sources, is a safe, effective and practical therapy for treating acne. And today, ALA-PDT has the additional benefit of working quickly compared to oral and topical medications.

Chicago - Laser and light sources have become important new additions to the dermatologist's tool chest of acne treatments.

Even more recently, however, dermatologists have begun to use topical aminolevulinic acid photodynamic therapy (ALA-PDT) to enhance the effects of light and laser acne treatments.

While topical ALA-PDT is approved by the Food and Drug Administration (FDA) for use in actinic keratosis, the current body of research suggests that the therapy, used in combination with laser or light sources, is a safe, effective and practical therapy for treating acne. And today, ALA-PDT has the additional benefit of working quickly compared to oral and topical medications, says Ashish C. Bhatia, M.D., dermatologist, assistant professor of clinical dermatology, Northwestern University Feinberg School of Medicine, Chicago.

"In the U.S., a solution of aminolevulinic acid (ALA) is applied to the skin, which, when absorbed into the skin, is converted to the active photosensitizing agent, protoporphyrin IX. When the agent is irradiated with a wavelength within its activation spectrum, whether it is a laser or other light source, it generates highly reactive free radicals and singlet oxygen species, causing damage to the adjacent cells," Dr. Bhatia says.

Light and lasers

Even without ALA-PDT, light sources and lasers alone have been proven effective for acne because these technologies kill the P. acnes bacteria or damage sebaceous glands.

"Interestingly, the bacterium itself produces porphyrins and thus, by activating these porphyrins, lights and lasers can destroy the P. acnes. The heat generated by some light and laser technology can also damage the sebaceous glands directly," Dr. Bhatia says.

The light sources and lasers used in dermatology to treat acne include blue light sources, which generate visible light in the blue spectrum. Intense pulsed light (IPL) devices produce a broad band of light, and lasers, such as the pulse dye lasers, KTP laser, and infrared lasers, are also used by dermatologists.

"The infrared lasers, such as the 1450 nanometer diode laser, 1320 nanometer Nd:YAG laser, and the 1540 nanometer erbium:glass laser, are also beneficial in the treatment of acne scarring, thus serving a dual purpose for certain patients," Dr. Bhatia elaborates.

While blue light and IPL technologies work by activating porphyrin, pulsed dye and KTP lasers may activate porphyrins, as well as affect the dilated vasculature portion of the inflammatory acne, helping to diminish the redness associated with inflammatory lesions. The infrared lasers approved for treatment of acne primarily work by thermolysis of the sebocytes and the P. acnes bacteria around them, he says.

Adding ALA-PDT to the mix

"There were several other studies, early on, that showed that different lasers and light sources did moderately well in improving acne," Dr. Bhatia says.

"But what we really wanted to achieve was the goal of sustained clearance of acne with no or minimal downtime for the patient. Unfortunately, the early studies using ALA-PDT incubation periods of three hours or more did clear the acne, but caused significant downtime because of a classic PDT effect, where the skin exhibits redness, inflammation and swelling of the treated areas; then, subsequent resolution with or without peeling."

With the use of short contact ALA-PDT (SC-ALA-PDT), using one-hour incubation periods, dermatologists are able to improve acne with minimal or no downtime. Early reports, such as one by Gold et al. (The use of a novel intense pulsed light and heat source and ALA-PDT in the treatment of moderate to severe inflammatory acne vulgaris. J Drugs Dermatol. 2004;3(6):S14-S18) have demonstrated the clinical efficacy and patient tolerance of these treatments.