PHOENIX – lesions, results from a prospective, single-center study showed.
“Acne vulgaris is the most common inflammatory dermatosis worldwide, often resulting in sequelae such as scarring, PIE, and PIH,” presenting author Jamie Hu, MD, said at the annual conference of the American Society for Laser Medicine and Surgery, where the study results were presented during an abstract session. “This dyschromia can cause greater psychological distress than the original acne lesions, and disproportionately affects skin of color patients.”
Blemish-prone skin is known to have higher levels of sebum and lower levels of antioxidants, leading to lipid peroxidation and oxidative stress, resulting in proliferation of Cutibacterium acnes and an inflammatory cascade that has recently been implicated in postinflammatory dyschromia and the development of PIE and PIH, noted Dr. Hu, a dermatology resident at the University of Miami. “Therefore, the use of antioxidants presents an opportunity to disrupt blemish and dyschromia,” she said.
One such antioxidant is silymarin, which is derived from the milk thistle plant. Recent studies have demonstrated that silymarin reduces proinflammatory mediators, prevents lipid peroxidation, and presents a new way to target the treatment of both acne and postinflammatory dyschromia.
Dr. Hu’s mentor,, owner and medical director of the Miami Dermatology and Laser Institute, hypothesized that nonablative laser therapy followed by topical application of silymarin would improve acne-associated postinflammatory dyschromia. To test her hunch, she conducted a 12-week, prospective trial in which 24 patients with PIE and/or PIH were randomized to one of two treatment arms: laser treatment with topical antioxidants or laser treatment with vehicle control. Patients received three laser treatments, each 1 month apart. The topical antioxidant used was , a serum that contains 0.5% silymarin, 0.5% salicylic acid, 15% L-ascorbic acid, and 0.5% ferulic acid. (The study was sponsored by SkinCeuticals, the manufacturer of the serum.)
Laser selection was made primarily on the type of dyschromia, with PIE patients receiving treatment with the pulsed dye laser and PIH patients receiving treatment with the 1,927-nm thulium laser. Patients were treated on days 0, 28, and 56 of the 12-week study, followed by immediate application of topical antioxidants or vehicle control. They were also instructed to apply the assigned topical twice daily for the duration of the study. Patients ranged in age from 21 to 61 years, and 20 had skin types III-IV.
To evaluate efficacy, the researchers conducted blinded clinical assessments with the postacne hyperpigmentation index (PAHPI) and the Global Aesthetic Improvement Scale (GAIS), instrumentation with the Mexameter, a device that captures erythema and melanin index values, and visual diagnostics with optical coherence tomography (OCT).
Dr. Hu reported that at week 12, the PAHPI in the silymarin-plus-laser treatment group fell from an average of 3.18 to 1.74 (a decrease of 1.44), which suggested an improvement trend, compared with the laser treatment–only group, whose PAHPI fell from an average of 3.25 to 1.97 (a decrease of 1.28).
As for the GAIS, a one-time score assessed at the end of the trial, the average score for all patients was 3.24, which translated to “much improved/very much improved.” Patients in the silymarin-plus-laser treatment group had higher average scores compared with patients in the laser treatment–only group (3.35 vs. 3.10, respectively), but the differences did not reach statistical significance.
According to results of the Mexameter assessment, paired t-tests showed that the levels of intralesional melanin decreased significantly for patients in the silymarin-plus-laser treatment group, compared with the laser treatment–only group (P < .05). OCT assessments demonstrated an increase in dermal brightness in both groups, corresponding to an increase in dermal collagen, as well as an increase in blood vessel density.
In an interview at the meeting, Dr. Waibel, subsection chief of dermatology at Baptist Hospital of Miami, said that future studies will focus on long-term follow-up to determine if acne scars can be prevented by combining silymarin with lasers to prevent PIH and PIE. “That would be priceless,” she said. “I believe that the PIH is what causes damage to the collagen, and that damage to the collagen is what causes the scarring. So, if we can prevent or treat PIH, we may be able to prevent scarring.”
This approach, she added, “would decrease the pharmaceutical cost because I think there are many dermatologists who are treating PEI and PIH as active acne. You really have to have a keen eye for understanding the differences and you really have to be looking, because PIE and PIH are flat, whereas active acne consists of either comedones or nodules.”
She noted that in skin of color patients, she has seen PIH persist for 9 or 10 months after treatment with isotretinoin. “It’s not the isotretinoin causing the scars, or even the acne, it’s the prolonged inflammation,” she said.
, a Boston-based laser and cosmetic dermatologist who was asked to comment on the study, said that patients and dermatologists frequently seek alternatives to hydroquinone for unwanted hyperpigmentation.
“This topical contains an active ingredient – silymarin – obtained from the milk thistle plant along with several already well known topicals used for the treatment of acne and PIH,” said Dr. DiGiorgio, program co-chair of the 2023 ASLMS conference. “Further and larger studies are needed to demonstrate and support the effectiveness of this product and silymarin for PIH and/or PIE.”
, a Los Angeles–based laser and cosmetic dermatologist, told this news organization that the study findings demonstrate the power of combining topical and laser treatment for more effective improvement in acne-related PIH.
“While the study failed to show statistically significant improvement in postinflammatory erythema with concomitant laser and topical therapy versus laser alone, the promising data supporting concurrent use of topicals and fractional lasers for treatment of PIH, particularly in dark skin phototypes, is a clinically impactful contribution to our daily practice,” he said.
Dr. Waibel disclosed that she has conducted clinical trials for many device and pharmaceutical companies including SkinCeuticals. Dr. Hu, Dr. DiGiorgio, and Dr. Jalian were not involved with the study and reported having no relevant disclosures.