Alfentanil (R-39209, trade name Alfenta, Rapifen in Australia) is a potent but short-acting synthetic opioid analgesic drug, used for anaesthesiainsurgery. It is an analogue of fentanyl with around one-fourth to one-tenth the potency, one-third the duration of action, and an onset of action four times faster than that of fentanyl.[3] Alfentanil has a pKa of approximately 6.5, which leads to a very high proportion of the drug being uncharged at physiologic pH, a characteristic responsible for its rapid onset. It is an agonist at mu opioid receptors.
Alfentanil
Clinical data
Alfenta
Micromedex Detailed Consumer Information
Legal status
Pharmacokinetic data
~50%
92%
90–111 minutes
15 min[2]
Identifiers
N-{1-[2-(4-ethyl-5-oxo-4,5-dihydro-1H-1,2,3,4-tetrazol-1-yl)ethyl]-4-(methoxymethyl)piperidin-4-yl}-N-phenylpropanamide
PubChem CID
YYYCompTox Dashboard (EPA)
Chemical and physical data
C21H32N6O3
416.526 g·mol−1
3D model (JSmol)
140.8 °C (285.4 °F)
O=C1N(\N=N/N1CC)CCN3CCC(N(c2ccccc2)C(=O)CC)(CC3)COC
InChI=1S/C21H32N6O3/c1-4-19(28)27(18-9-7-6-8-10-18)21(17-30-3)11-13-24(14-12-21)15-16-26-20(29)25(5-2)22-23-26/h6-10H,4-5,11-17H2,1-3H3 Y
Key:IDBPHNDTYPBSNI-UHFFFAOYSA-N Y
While alfentanil tends to cause fewer 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. Almost exclusively used by anesthesia providers during portions of a case where quick, fast-acting (though not long-lasting) pain control is needed (as, for example, during nerve blocks), alfentanil is administered by the parenteral (injected) route for fast onset and precise control of dosage.
Discovered at Janssen Pharmaceutica in 1976, alfentanil is classified as a Schedule II drug in the United States.[4]
Side effects of fentanyl analogs are similar to those of fentanyl itself and include itching, nausea and potentially life-threatening respiratory depression. Fentanyl analogs have killed hundreds of people throughout Europe and the former Soviet republics since the most recent resurgence in use began in Estonia in the early 2000s, and novel derivatives continue to appear.[5]
