A transdermal therapeutic system (TTS) comprises a silicone-based polymer adhesive system having distributed therein (-)-5,6,7,8-tetrahydro-6-[propyl-[2-(2-thienyl)ethyl]amino]-1-naphthaleno- l free base in an amount of about 5% to 40% by weight. The adhesive system comprises a silicone adhesive and an additive having increased solubility for the active substance, in an amount effective to increase dissolving capacity of the matrix for the active substance.