Fentanyl (Transdermal, Transbuccal, Transmucosal, Sublingual)
Norfentanyl
4-N-(N-propionylanilino) piperidine
4-N-(Nhydroxypropionylanilino) piperidine
1-(2-phenethyl)-4-N-(Nhydroxypropionylanilino) piperidine
(Source: Remitigate.com)
As for my experience with transdermal fentanyl, when I used that patch, I found them effective to 2 days only, after only 3-6 months of use.
For me, the problem with transdermal fentanyl was a rapid development of opioid tolerance.