Dermal therapeutic systems permeable to water vapour

Dermal therapeutic systems (DTS) are self-adhesive patches that consist of a flexible backing layer and an adhesive controlled release matrix layer containing the drug. They an formulated to obtain a controlled release of drugs in order to treat topical skin pathologies. As permeability to water vapour is an important characteristic for DTS, the aim of this work was to develop systems with different predictable water vapour permeabilities (WVP), to be selected according to the therapeutic needs of the treated disease, and with good adhesive properties. In the present study, the WVP of 12 materials, usable as backing layers, were tested. In order to prepare DTS, the artificial silk was selected as a backing layer as it has good water vapour permeability, compatibility with the coating process and cohesion with the matrices. Two adhesive hydrophilic copolymers of dimethylaminoethyl methacrylate and neutral methacrylic esters (Plastoid® E 35 M-Plastoid® E 35 L) mixed with a non-adhesive hydrophobic copolymer of ethylacrylate and methylmethacrylate, supplied in suspension in two different concentrations (Eudragit® NE 30 D-Eudragit® NE 40 D), were used to prepare four series of DTS. Water vapour permeability and adhesion properties of the prepared DTS were evaluated. Adding 10-30% w/w of Eudragit® NE to Plastoid® E 35 permits the formulation of patches with higher water vapour permeability and good adhesive properties.