Photodynamic Therapy (PDT)

Photodynamic Therapy (PDT) is the generic name for a class of treatments that use specialized medications called photosensitizers to increase the effectiveness of a light-based treatment. PDT is used treat certain types of skin problems, including acne and some forms of cancer.

Photodynamic Therapy (PDT) for the Treatment of Acne

Numerous clinical research studies have reported that Photodynamic therapy (PDT) can decrease bacterial levels in the skin and help improve acne symptoms. PDT appears to be more effective for treating inflammatory acne lesions (Acne Types: 2-4) than non-inflammatory acne lesions (Acne Types: 1-2). PDT has also been reported to be more effective at improving acne symptoms than Blue Light Phototherapy or IPL alone.

However, PDT treatment alone rarely results in complete resolution of acne symptoms. It is important to keep in mind that PDT, like most light therapies, provides only temporary benefit and treatment must be repeated regularly to achieve and maintain significant improvements.

In addition to killing acne-causing bacteria, PDT has been shown to damage the sebaceous glands and temporarily decrease sebum production. Because of these effects, PDT can be a very useful treatment for patients with inflammatory acne that also have sebaceous hyperplasia or excessively oily skin. The effect of a PDT treatment regimen on sebaceous gland activity and sebum production appears to be semi-permanent.

How Does Photodynamic Therapy (PDT) Work?

Photodynamic Therapy (PDT) involves topical application of a photosensitizer followed by exposure to a specialized, high-intensity light source. The photosensitizer causes certain kinds of cells to produce large amounts of light-absorbing molecules called porphyrins. The photosensitizing agent helps target the treatment to the appropriate cells.

The acne-causing Propionibacterium acnes (P. acnes) bacterium produces a unique porphyrin molecule that absorbs light in the blue spectrum (~415 nm). When this porphyrin molecule absorbs blue light, it produces free radical molecules that can kill the bacteria.

Aminolevulinic Acid (ALA) is the most common photosensitizer for PDT-based acne treatments. But three other photosensitizers are also occasionally used: MAL (methyl aminolevulinate), LA (levulinic acid) and IAA (Indole-3-Acetic Acid). MAL is generally used with red light sources and is more commonly used against cancer than acne.

Summary

PDT popular technique for many dermatologists, but it has received mixed reviews from acne patients. Because PDT requires the careful application of a photosensitizer and controlled light exposure, effective PDT treatments for acne can become quite expensive and time consuming. There are also potential risks associated with the photosensitizers themselves, such as allergic reactions, hypersensitivity to sunlight, redness and inflammation. In summary, while PDT can be an effective acne treatment, many people prefer frequent Blue Light Phototherapy over PDT because of the decreased risk of side effects.

References

A Comparative Study of Topical 5-Aminolevulinic Acid Incubation Times in Photodynamic Therapy with Intense Pulsed Light for the Treatment of Inflammatory Acne. Oh, et al. 2009.
A comparison of intense pulsed light, combination radiofrequency and intense pulsed light, and blue light in photodynamic therapy for acne vulgaris. Taub, et al. 2007.
The use of a novel intense pulsed light and heat source and ALA-PDT in the treatment of moderate to severe inflammatory acne vulgaris. Gold, et al. 2000.
Treatment of Inflammatory Facial Acne Vulgaris with Intense Pulsed Light and Short Contact of Topical 5-Aminolevulinic Acid: A Pilot Study. ROJANAMATIN, et al. 2006.
Effectiveness of Photodynamic Therapy with Topical 5-Aminolevulinic Acid and Intense Pulsed Light versus Intense Pulsed Light Alone in the Treatment of Acne Vulgaris: Comparative Study. Arianee, et al. 2005.
A comparative study of intense pulsed light alone and its combination with photodynamic therapy for the treatment of facial acne in Asian skin. Yeung, et al. 2007.
Photodynamic therapy of acne vulgaris with topical aminolaevulinic acid and incoherent light in Japanese patients. Itoh, et al. 2001.
Photodynamic therapy of acne vulgaris using 5-aminolevulinic acid versus methyl aminolevulinate. Wiegell, et al. 2006.
Photodynamic therapy for acne vulgaris with topical 5-aminolevulinic acid. Itoh, et al. 2000.
Photodynamic therapy of acne vulgaris using methyl aminolaevulinate: a blinded, randomized, controlled trial. Wiegell, et al. 2006.
Photodynamic Therapy of Acne. Sandberg, et al. 2001.
Topical ALA-photodynamic therapy for the treatment of acne vulgaris. Hongcharu, et al. 2001.
Photodynamic therapy for acne vulgaris: a pilot study of the dose-response and mechanism of action. Horfelt, et al. 2007.
Topical aminolaevulinic acid photodynamic therapy for the treatment of acne vulgaris: a study of clinical efficacy and mechanism of action. Pollock, et al. 2004.
In vivo porphyrin production by P. acnes in untreated acne patients and its modulation by acne treatment. Borelli, et al. 2006.

Photodynamic Therapy (PDT) Images