One of several light-based technologies under investigation for the treatment of acne vulgaris, photodynamic therapy (PDT) has shown impressive long-term results that may approach those achieved by isotretinoin. PDT is approved by the FDA only for the treatment of actinic keratosis.
"I feel there's increasing interest in PDT right now because it's getting more difficult to prescribe isotretinoin, and clinicians need an alternative for those patients who don't respond to conventional treatment," says Fernanda H. Sakamoto, MD, instructor in dermatology at Harvard Medical School and a researcher at the Wellman Center for Photomedicine, referring to the hurdles the iPledge program creates for patients and isotretinoin's side effects, which may give patients pause.
Noting that bright visible light can moderately improve acne, Drs. Sakamoto, Lopes, and Anderson say it appears that "naturally occurring porphyrins within sebaceous follicles act as endogenous photosensitizers to visible light." Intense blue light is an FDA-approved treatment for acne, but the authors state that all light-alone treatments have only temporary effects and seem to be effective only against mild to moderate acne.
Clinicians offering PDT to their patients must consider various light sources and wavelengths, light dosimetry, drug incubation time, and skin preparation. Most clinicians who are treating acne with PDT are using low-dose methods in an effort to make the treatment more easily tolerated and less time-consuming.
The most common side effects of PDT for acne are moderate to severe pain, erythema typically lasting 3 to 5 days, edema usually occurring 1 to 4 days after treatment, and hyperpigmentation which can persist up to 4 weeks after a treatment.
Experts agree the PDT may still have a place in the treatment armamentarium. "The role of PDT is a little dicey, but the believe dermatologists should discuss it with patients as a treatment option," says Dr. Choudhary. "There are many people who can't take isotretinoin, so PDT seems to be a great alternative treatment," says Dr. Sakamoto. It's a trade-off. The way PDT is best performed today, in a high-dose modality, it's not easy on the patient. But in the end, they're very happy with the results."
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