Erfindungsgemäß wird ein transdermales therapeutisches System zur Verabreichung von Fentanyl oder einem Analogstoff davon durch die Haut zur Verfügung gestellt, das eine haftklebende Matrixschicht aufweist, die ein Gemisch aus zwei Polyisobutylenen mit bestimmten Speichermodulen enthält.Transdermal therapeutic system comprises: (a) a backing layer； (b) a pressure-sensitive adhesive matrix layer containing the active substance； and (c) a release liner, where active substance is fentanyl or its analogue including alfentanil, carfentanil, lofentanil, remifentanil and trefentanil or their salts. The matrix layer comprises first polyisobutylene and/or second polyisobutylene as pressure-sensitive adhesive polymer. The first polyisobutylene has storage modulus, which is constant at 10-40[deg] C and second polyisobutylene has storage modulus, which decreases continuously at 10-40[deg] C. Transdermal therapeutic system comprises: (a) a backing layer； (b) a pressure-sensitive adhesive matrix layer containing the active substance； and (c) a release liner, where the active substance is fentanyl or its analogue including alfentanil, carfentanil, lofentanil, remifentanil and trefentanil or their salts. The matrix layer comprises first polyisobutylene and/or second polyisobutylene as pressure-sensitive adhesive polymer. The first polyisobutylene has a storage modulus, whose value is substantially constant at the temperature of 10-40[deg] C and the second polyisobutylene has a storage modulus, whose value decreases continuously at the temperature of 10-40[deg] C with increasing temperature. The storage modulus in the linear visco-elastic region at a frequency of 10 rad/second is measured using a rheometer with parallel plate geometry, where the pressure-sensitive adhesive matrix layer contains undissolved active substance in the form of active substance particles. An independent claim is also included for producing the transdermal therapeutic system, comprising dispersing the activ
