Donepezil Patch Shows Favorable Results on Skin Irritation Trial

Corium, LLC, recently announced positive skin tolerability results from a study of its donepezil transdermal system (TDS, Adlarity) to treat patients with mild, moderate, and severe dementia of the Alzheimer’s type.¹ In the 3-week trial the test patches showed no to minimal skin irritation in most subjects.

The double-blind phase 1 study²(NCT03397862) followed 256 adults for 3 weeks. The Adlarity patch was placed on 1 side of patient’s back and a placebo patch was placed on other. Once a week the patches were changed and replaced with a patch on the same location. In contrast, instructions for use of the Adlarity patch advise patients not to place the patch on the same location for at least 14 days following removal from that location.

Adlarity is the first and only US Food and Drug Administration (FDA) approved once-weekly TDS for patients with mild, moderate, and severe dementia of the Alzheimer’s type. The patch delivers a continuous dose of donepezil, resulting in a generally favorable gastrointestinal adverse event profile.

Researchers evaluated skin irritation on days 8, 15, and 22 using a combined skin irritation score (CSIS) from the Dermal Response Scale and an Other Effects Scale. The Adlarity patch caused none to minimal skin irritation in most patients after 3 weeks, scoring an average .55 points (±.78) of a maximum possible 7 points using a calculation of the mean CSIS scores across 3 weekly measures. The placebo patch scored .19 (±.35), which indicated no irritation.²

"These important data show that the once-weekly Adlarity skin patch had good adhesion and overall mild to no skin irritation despite the exaggerated conditions used during testing," said lead author Marwan N. Sabbagh, MD, professor of neurology at the Barrow Neurological Institute in Phoenix, Arizona, in a news release. "The results grow our understanding of Adlarity’s safety profile and provide additional information that should be helpful to clinicians when considering the only weekly skin patch formulation of donepezil for their Alzheimer's patients."¹

The patches showed generally good adhesion. If a patch was removed either intentionally or it fell off but was replaced within 24 hours, the patient remained in the study. Most of the patients (59.4%) were women and white (99.2%).²

Treatment-emergent adverse events (TEAEs) were reported in 76.2% of patients, and 11 patients discontinued the study due to TEAEs. Of those 11, 1 discontinued due to erythema, discharge, and edema. The other 10 discontinued due to high blood pressure. The other reported TEAEs included application-site pruritis (40.2%), headache (18.4%), nausea (18%), abnormal dreams (18%), muscle spasms (16.8%), and insomnia (10.2%).

A higher incidence of application-site TEAEs was reported for donepezil TDS (38.7%) compared to the placebo TDS (27.7%), which included pruritis and application-site pain.²

Donepezil TDS showed favorable skin tolerability and adhesion with no safety concerns, demonstrating that “the donepezil TDS provides safe and effective therapy for the treatment of patients with Alzheimer disease.”²

References

1. Corium announces publication of favorable Adlarity (donepezil transdermal system) skin irritation clinical trial data. News release. September 12, 2023. Accessed September 12, 2023. https://prnmedia.prnewswire.com/news-releases/corium-announces-publication-of-favorable-adlarity-donepezil-transdermal-system-skin-irritation-clinical-trial-data-301924112.html
2. Sabbagh MN, Mathew P, Blau A. A randomized double-blind study to assess the skin irritation and sensitization potential of a once-weekly donepezil transdermal delivery system in healthy volunteers. Alzheimer Dis Assoc Disord. Published online September 11, 2023. doi:10.1097/WAD.0000000000000578