Alfentanil

Alfentanil, sold under the brand name Alfenta among others, is a potent, short-acting synthetic opioid analgesic drug used for anesthesia in surgery. 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 of the μ-opioid receptor.

Trade namesAlfenta, Rapifen, others

Other namesR-39209

AHFS/Drugs.comMicromedex Detailed Consumer Information

MedlinePlusa601130

Quick facts Clinical data, Trade names ...

Alfentanil

Above: Alfentanil structure Below: 3D model of alfentanil molecule
Clinical data
Trade names	Alfenta, Rapifen, others
Other names	R-39209
AHFS/Drugs.com	Micromedex Detailed Consumer Information
MedlinePlus	a601130
Routes of administration	Intravenous, subcutaneous
Drug class	Opioid
ATC code	N01AH02 (WHO)
Legal status
Legal status	AU: S8 (Controlled drug) BR: Class A1 (Narcotic drugs)[1] CA: Schedule I DE: Anlage III (Special prescription form required) UK: Class A US: Schedule II
Pharmacokinetic data
Bioavailability	IV/IM/SC: 100%
Protein binding	92%
Metabolism	Hepatic
Elimination half-life	90–111 minutes
Duration of action	15 minutes[2]
Identifiers
IUPAC name 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
CAS Number	71195-58-9 Y
PubChem CID	51263
IUPHAR/BPS	7108
DrugBank	DB00802 Y
ChemSpider	46451 Y
UNII	1N74HM2BS7
KEGG	D07122 Y
ChEBI	CHEBI:2569 Y
ChEMBL	ChEMBL634 Y
CompTox Dashboard (EPA)	DTXSID9022570
ECHA InfoCard	100.295.336
Chemical and physical data
Formula	C21H32N6O3
Molar mass	416.526 g·mol−1
3D model (JSmol)	Interactive image
Melting point	140.8 °C (285.4 °F)
SMILES O=C1N(\N=N/N1CC)CCN3CCC(N(c2ccccc2)C(=O)CC)(CC3)COC
InChI 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
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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]