| abstract |
Disclosed is a transdermal therapeutic system for administering an active substance through the skin, comprising: a) a backing; b) a reservoir that is located on the backing and comprises b1) a first layer containing active substance, at least one gelatinizing agent, at least one emollient, and a first polyisobutylene, and b2) a second layer containing active substance, at least one gelatinizing agent, at least one emollient, and a second polyisobutylene that is different from the other polyisobutylene. At least the first layer contains undissolved active substance in the form of active substance particles, said active substance being fentanyl or a fentanyl analogue. |