Alfentanil

Alfentanil (R-39209, trade name Alfenta, Rapifen in Australia) is a potent but short-acting synthetic opioid analgesic drug, used for anaesthesia in surgery. It is an analogue of fentanyl with around 1/4 the potency of fentanyl and around 1/3 of the duration of action, but with an onset of effects 4x faster than fentanyl. It is an OP3 mu-agonist.

While alfentanil tends to cause less cardiovascular complications than other similar drugs such as fentanyl and remifentanil it tends to give stronger respiratory depression and so requires careful monitoring of breathing and vital signs. Alfentanil is administered by the parenteral (injected) route for fast onset of effects and precise control of dosage.

Alfentanil is a restricted drug which is classified as Schedule II in the USA, according to the U.S. DEA website.

Alfentanil was discovered at Janssen Pharmaceutica in 1976.