Fentanyl comes in injection form, as a skin patch, an effervescent tab (like the Actiq lollipop), and a mouth spray with other delivery methods currently in development. http://en.wikipedia.org/wiki/Fentanyl

The Fentanyl patch is also known as: Actiq, Durogesic, Duragesic, Fentora, Onsolis, Instanyl, and Abstral.

If those names are not familiar, maybe the patch you used was Norspan (buprenorphine)? Norspan is not the same as Fentanyl, but often used as a first choice pain reliver because it doesn't fall under the category of opiates.

There may be other brands of skin patch that I'm unaware of. Also, I'm in Australia not America, and our medications often differ from your's, but should you post a question in the Medication Forum, I'm sure mrsD would be happy to answer it for you.