| abstract |
The invention concerns a transdermal therapeutic system containing 17-beta-oestradiol, as its active substance; the system having a laminate structure built up on a back film which is substantially impermeable both to the active substances and to water, with one or more matrix films and, optionally, an adhesive film. The system is characterised in that at least one of the matrix films or the adhesive film contains anhydrous 17-beta-oestradiol in crystalline form. A method for the preparation of the transdermal therapeutic system includes preparing suspension of a 17-beta-oestradiol semihydrate in a solution, dispersion, or in a melt of the matrix base material. Said suspension is thereafter applied in the form of a layer upon a foil of the base material, the layer is dried and the coated base thus obtained is heated in the range from 90 to 175 degrees Ceslius. The 17-beta-oestradiol semihydrate is converted to anhydrous 17-beta-oestradiol, a part whereof is in crystalline form. |