DERMAL THERAPEUTIC SYSTEMS PERMEABLE TO WATER-VAPOR

Dermal therapeutic systems (DTS) are self-adhesive patches that consis t of a flexible backing layer and an adhesive controlled release matri x layer containing the drug. They are formulated to obtain a controlle d release of drugs in order to treat topical skin pathologies. As perm eability to water vapour is an important characteristic for DTS, the a im of this work was to develop systems with different predictable wate r vapour permeabilities (WVP), to be selected according to the therape utic needs of the treated disease, and with good adhesive properties. In the present study, the WVP of 12 materials, usable as backing layer s, were tested. In order to prepare DTS, the artificial silk was selec ted as a backing layer as it has good water vapour permeability, compa tibility with the coating process and cohesion with the matrices. Two adhesive hydrophilic copolymers of dimethylaminoethyl methacrylate and neutral methacrylic esters (Plastoid(R) E 35 M-Plastoid(R) E 35 L) mi xed with a non-adhesive hydrophobic copolymer of ethylacrylate and met hylmethacrylate, supplied in suspension in two different concentration s (Eudragit(R) NE 30 D-Eudragit(R) NE 40 D), were used to prepare four series of DTS. Water vapour permeability and adhesion properties of t he prepared DTS were evaluated. Adding 10-30% w/w of Eudragit(R) NE to Plastoid(R) E 35 permits the formulation of patches with higher water vapour permeability and good adhesive properties. (C) 1997 Elsevier S cience B.V.