Phototherapy garners interest for acne tx

July 1, 2005

New Orleans — While treatment of acne with lasers and light sources is here to stay, phototherapy for acne is still an evolving field, and further research is needed to optimize outcomes, according to David J. Goldberg, M.D., J.D., who spoke at the 63rd Annual Meeting of the American Academy of Dermatology.

"When light treatment for acne was first introduced several years ago, I was skeptical about its future role and expected it to be a passing fad. However, safety problems associated with current therapeutic modalities for acne, concerns about increasing antibiotic resistance and the never-ending desire to develop high-tech therapeutic modalities have together fueled interest in developing laser and light source treatments that seem to offer efficacy with the advantage of a very favorable safety profile," Dr. Goldberg says. He is a contributor to Dermatology Times, clinical professor of dermatology and director, laser research and Mohs surgery, Mt. Sinai School of Medicine, as well as adjunct professor of law, Fordham Law School, New York.

Defining targets Destruction of Propionibacterium acnes and the sebaceous gland are the two primary targets of phototherapy approaches to acne treatment, although some devices may also provide a benefit through an anti-inflammatory mechanism. Modalities aimed at reducing P. acnes colonization include blue (ClearLight, Lumenis; Blu-U, Dusa; OmniLux Blue, Alderm) and red (OmniLux Revive, Alderm) light-emitting sources, 585 nm to 595 nm pulsed dye lasers, 532 nm KTP lasers, and intense pulsed light sources. These devices are thought to work by inducing photoexcitation of bacterial porphyrins that leads to production of singlet oxygen and ultimately bacterial destruction.

"As soon as the treatment is stopped, the bacteria recolonize and acne may flare within a few months," Dr. Goldberg says.

Energy from longer wavelength, infrared lasers, including the 1320 nm Nd:YAG laser (CoolTouch 3, CoolTouch) and the 1450 nm diode laser (Smoothbeam, Candela), as well as from the radiofrequency device (ThermaCool TC™, Thermage) penetrates deeper into the skin where it is thought to cause thermal injury to the sebaceous gland. By causing temporary gland shrinkage, they reduce sebum production and seem to be associated with more profound and durable clearing relative to the devices that eradicate P. acnes.

"As a simultaneous benefit, treatment with these devices also stimulates collagen remodeling and so they may also improve acne scarring," Dr. Goldberg says.

Sessions are usually repeated at monthly intervals for a total of five treatments. Onset of response generally occurs after the second treatment and disease control persists for six to 12 months after the last session.

PDT approach More recently, a photodynamic therapy (PDT) approach using topical 5-aminolevulinic acid 20 percent (5-ALA, Levulan Kerastick, Dusa) applied for a 30 minute to 60 minute contact period followed by irradiation with a pulsed dye laser, intense pulsed light source, or blue or red light source has been investigated for treating acne. This strategy takes advantage of preferential accumulation of 5-ALA and production of protoporphyrin IX in the sebaceous gland to result in greater damage to that structure. Relative to treatment with the longer wavelength lasers or the radiofrequency device, 5-ALA PDT for acne seems to offer a benefit for hastening the response.

"The final outcome achieved with this procedure is not any better than that achieved using the laser/light only approaches targeting the sebaceous gland. However, clinical improvement may be seen after just one treatment and a total of only three sessions may be needed to achieve the optimal response," Dr. Goldberg says.

For acne sufferers, 5-ALA PDT is well-tolerated. Patients may develop some transient erythema and need to avoid the sun for two days post-treatment.