Dallas — A chemiluminescent mask for photodynamic therapy (PDT) with 5-aminolevulinic acid (ALA) may have efficacy in mild to moderate acne, according to Brian Zelickson, M.D.
"This inexpensive, disposable light source could potentially be prescribed so patients could use it at home," Dr. Zelickson says. "The mask is a geared-up 'glow stick,' like the Halloween toy. Two chemicals mixed together become activated and produce light of many different wavelengths. We are initially testing the blue to blue-green wavelength range. Since fluences are defined by the mask, we don't have to set them, and that's the beauty of the technique," Dr. Zelickson says.
OmniGlow, the manufacturer of the light device, makes similar chemiluminescent sticks for the military, he adds.Test subjects Dr. Zelickson's trial patients apply ALA for one to two hours, then wear the proprietary light mask for another hour.
"When we get the energy up higher, we will reduce the time the patient wears the mask," he explains.
Dr. Zelickson, who has used a similar treatment protocol and light device to treat actinic keratoses, presented the results of his pilot study with acne at the annual meeting of the American Society for Laser Medicine and Surgery (ASLMS) here recently.
According to Dr. Zelickson, conventional treatment of acne includes topical and oral medications (primarily antibiotics), topical retinoids and oral hormones.
"Recently a blue light source and an infrared laser have been cleared by the FDA, but these are still not conventional treatments," he says. "Since we are seeing more and more patients with resistance to antibiotics, and who don't want hormonal therapy or vitamin A derivatives such as isotretinoin, these new modalities are becoming popular."
In ALA PDT for acne, topical ALA enters the pilosebaceous glands and is converted to photosensitive protoporphyrin IX (PpIX), according to Dr. Zelickson.
"We shine light to activate the PpIX, which injures the bacteria and pilosebaceous glands," he explains. "Studies over the past several years have shown good efficacy with this treatment model. We had a couple early patients with moderate to severe cystic lesions and they did quite well. My feeling is that treatment with our current light source might be better for mild to moderate inflammatory acne."
Although Dr. Zelickson currently gives isotretinoin to patients with a lot of cystic nodules, it may not be effective, he adds.
So far Dr. Zelickson has used the novel technique on seven or eight patients.
"Although we are still establishing treatment parameters, we currently give weekly treatments for four weeks," he says. "Retreatments are identical to the initial treatment — ALA for one hour, the mask for one hour, then go home. Some patients have seen improvement after the first treatment, but sometimes it takes two to three treatments."
One or two patients had exacerbation of acne within one week after the first treatment, similar to that seen with isotretinoin during the first few months, according to Dr. Zelickson.
"We let the exacerbation burn out, do another ALA PDT treatment, and it clears up," he says. "We have a strict study protocol, so we could not use any ancillary therapy."
Two of the trial patients have been followed for six months without recurrence of acne lesions, Dr. Zelickson says.
"There is some durability, but I suspect a lot of patients will need maintenance therapy. I don't see this as a cure of acne. In our early studies we saw 30 to 70 percent clearance." Although most trial patients have had Fitzpatrick skin types II to III, Dr. Zelickson has noted no difficulties in patients with darker skin. So far he has not tried the technique in combination with other treatments.
Refining parameters Dr. Zelickson plans to continue refining parameters such as shortening the light exposure time and generating more intense energy of the appropriate wavelength. "We've had good success with actinic keratoses," he said. "With acne, our target is a little deeper, so we are modifying our protocol for that and other applications."