Electrospun dressings with a dual release functionality of two anti-inflammatory active ingredients†

Inflammatory skin conditions are commonly treated using topical semi-solid formulations such as creams, ointments, or gels. However, the use of such formulations is often connected to poor patient adherence due to the greasiness of the formulations and the need to apply different products multiple times a day. To overcome this challenge, we aimed to develop an anti-inflammatory electrospun dressing containing two active ingredients with a reduced application frequency of once a day, enhancing the treatment comfort for the patients. Salicylic acid and hydrocortisone were combined in a polycaprolactone-based electrospun fiber dressing with a dual release functionality, featuring both a burst and sustained release of salicylic acid and hydrocortisone, respectively. While electrospun dressings have been extensively studied in terms of their material characteristics and drug release behavior, few studies have explored their release behavior in conjunction with their skin permeation performance. Our study bridges this gap by providing and comparing both drug release and skin permeation data. We found a rapid release of salicylic acid and a delayed release of hydrocortisone in our layer-by-layer system. Although significantly less hydrocortisone was released from the layer-by-layer system in the permeation studies compared to the release studies, hydrocortisone still permeated through different skin layers. Moreover, we verified the anti-inflammatory properties of the electrospun dressing in studies on human keratinocytes and human skin. Special emphasis was placed on comparing results with standard pharmaceutical formulations, namely a hydrocortisone cream and a salicylic acid ointment. Permeation studies showed higher hydrocortisone penetration into the skin from the layer-by-layer fiber dressing compared to standard formulations. Our findings highlight the feasibility of combining multiple drugs in a single electrospun fiber system, while achieving controlled release behavior through tuning the composition of the drug delivery system. Our study moreover confirms that conducting permeation experiments alongside release studies is crucial for correlating results and evaluating the effectiveness of a drug delivery system.