Patent ID: 8017146

Claim:
A Transdermal delivery device for the transdermal delivery of an active substance, including a pharmaceutically active substance, the device comprising: a. a release layer detachable when the device is used; b. a first pressure sensitive adhesive layer, coated over the release layer; c. a second adhesive layer, coated over said first layer; the ratio of the thickness of the first layer to the thickness of the second layer being in the range of 1.2-7:1; d. a backing layer, coated over said second adhesive layer substantially impermeable to the active substance; and wherein the first and second layers comprise a polymer selected individually from the group consisting of acrylic polymers, polyisobutylenes and silicone elastomers; wherein: 1. the first layer is adapted to be brought into contact with the skin; 2. the active substance is present and dissolved in both of said first and second layers; 3. the affinity of said first layer for the active substance is between about 1.15 and about 10 times lower than that of said second layer; 4. the percent saturation of said active substance in both of said first and second layers is the same and both are less than 100%; and 5. the second layer replenishes the first layer, as the active substance is delivered to a patient, and the combination of the relative thicknesses of the first and second layers and their relative affinities for the active substance determines the delivery profile, achieving a highly constant efflux rate during use.