Pretreatment with microneedles provided a faster, less painful, way to treat facial actinic keratoses (AKs) with photodynamic therapy, with similar clearance rates as would be expected with traditional therapy, in a study of 33 patients.
This approach reduced the incubation time of aminolevulinic acid (ALA) to 20 minutes, with comparable results to one-hour ALA incubation times. “Interestingly, the secondary outcome of pain associated with blue light exposure during photodynamic therapy was nominal and not significantly different from the sham side,” reported, and her associates in the department of dermatology at the University of California, Davis (JAMA Dermatol. 2017 May 17. ).
“Pain associated with PDT is the most severe adverse effect and may lead to interruption or discontinuation of treatment, resulting in refusal to repeat the process at a future date owing to unbearable discomfort,” they wrote. Patients also reported little to no swelling or pain after treatment and minimal erythema and peeling.
The randomized, split-face, single-blinded controlledenrolled 33 patients, with at least eight AKs on their faces, from a university dermatology outpatient clinic from 2015 to 2016. They were randomized to receive either 10 minutes or 20 minutes incubation time with ALA, and 32 completed the study. Those in the 20-minute group had a mean of 25 grade II facial AKs, and those in the 10-minute group had an average of 31 grade II facial AKs.
Before administration of ALA, each patient received pretreatment with a microneedle roller on one side of their face and a sham roller on the other side. On each half of their faces, the microneedle device (a single-use sterile array of microneedles measuring 200 mcm) or sham roller was rolled forward and backward eight times in four directions.
They were exposed to blue light for 1,000 seconds at an average wavelength of 478 nm, an overall fluence of 10 J/cm2, and advised to avoid sun exposure for 36 hours after treatment.
At follow-up one month later, among the patients with a 20-minute ALA incubation time, the mean AK clearance rate was 76% on the side with microneedle pretreatment, compared with 58% on the sham side (P less than .01). This included three patients with complete clearance. The efficacy of microneedle pretreatment with a 20-minute incubation time is similar to that of 1-hour incubation times with ALA. PDT typically uses 1-4 hours of incubation time.
Among the patients who received a 10-minute ALA incubation time, a mean of 43% of AKs on the microneedle side and 38% on the sham side cleared, a difference that was not statistically significant. Participants did not rate the pain as significantly different between each side of their face and both groups reported low levels of pain overall.
One limitation of the study was the short follow-up time. “Because actinic damage is cumulative, there is potential for thicker AKs to recur or for new lesions to develop during a longer follow-up period,” the authors noted.
The research was partly funded by an author’s University of California, Davis, Medical Student Research Fellowship. The authors reported having no disclosures.