TRANSDERMAL DEVICE

PCT No. PCT/GB91/01730 Sec. 371 Date Apr. 5, 1993 Sec. 102(e) Date Apr. 5, 1993 PCT Filed Oct. 4, 1991 PCT Pub. No. WO92/05811 PCT Pub. Date Apr. 16, 1992.The invention pertains to a method of preparing a device for transdermal delivery of an active ingredient which is solid at room temperature and in which part or all of the active ingredient is present in a saturated or supersaturated solution. In the first step, a mixture is prepared which includes at least a polymer adhesive, a vehicle for the polymer adhesive, an active ingredient and a solvent mixture for the active ingredient which solvent mixture comprises at least two solvents having different boiling points. The mixture is then formed into a film and dried. The vehicle for the polymer adhesive and at least one of the solvents and the solvent mixture have boiling points below the drying temperature of the film, while at least one of the solvents in the solvent mixture has a boiling point above the drying temperature of the film. Thus, at least one of the solvents remains in the film after drying and the solubility of the active ingredient contained in the remaining solvent is greater than 10%.