Fentanyl is a synthetic opioid analgesic that is approximately 80 times more potent than morphine. As such, it is a Schedule II controlled substance, which means there are specific regulations regarding its use. The intravenous formulation of fentanyl was approved by the Food and Drug Administration (FDA) in the 1960s under the trade name of Sublimaze. Since that time, several other dosage forms have been FDA approved under different trade names (see Table 1). Fentanyl is not absorbed well when taken by mouth and swallowed, thus the other dosage forms are designed to allow fentanyl to be absorbed either though the skin [Page 401](transdermal) or through the mucous membranes in the mouth (buccal).