Visualization of Topical Roflumilast Versus Vehicle using Line-Field Optical Coherence Tomography in Healthy Skin

Roflumilast is a topical phosphodiesterase-4 inhibitor FDA-approved for treating plaque psoriasis and atopic dermatitis. Line-field confocal optical coherence tomography (LC-OCT) is a novel non-invasive imaging method utilized to evaluate skin in vivo.

This study uses LC-OCT (Damae Medical, France) to visualize the effects of 0.3% roflumilast versus vehicle on healthy skin in vivo.

Three subjects (mean age: 26 years) with healthy skin applied roflumilast (right forearm) and vehicle (left forearm) daily for seven days. LC-OCT imaging was performed at multiple intervals: before cream application (T0A), after application (T0B), 15 minutes (T0C), 1 hour (T0D), 8-12 hours (T0E), 24 hours (T0F), 7 days (T7), and 7 days after the last application (T14). A dermatopathologist evaluated changes in morphology, and an AI algorithm calculated the changes in stratum corneum (SC) and epidermal thickness.

At T0B, both creams showed a hyperreflective layer above the SC, which diminished over time. Roflumilast-treated skin exhibited increased dermal-epidermal junction (DEJ) demarcation, more organized keratinocytes, and a reduction in hyperreflective material. The algorithm showed increased SC thickness in both arms until T7, but only roflumilast's SC thickness continued increasing until T14, while the vehicle-treated arm decreased. Epidermal thickness increased in both arms but reversed at T14.

LC-OCT visualized roflumilast's effects on healthy skin, including reduced hyperreflective material consistent with mottled pigmentation and normalized keratinocyte organization, suggesting the effects it has on healthy skin. The AI algorithm showed lasting effects on SC thickness, even after discontinuation of treatment.