Etorphine

Etorphine

Clinical data
AHFS/Drugs.com	International Drug Names
ATCvet code	QN02AE90 (WHO)
Legal status
Legal status	AU: S9 (Prohibited) CA: Schedule I DE: Anlage III (Prescription only) US: Schedule I and II UN: Narcotic Schedules I and IV List 1 (Netherlands)
Identifiers
IUPAC name 6,14-endoetheno – 7 a (1-(R)-hydroxy-1 methylbutyl)-tetrahydro-nororipavine
CAS Number	14521-96-1 N
PubChem (CID)	644209
DrugBank	DB01497 Y
ChemSpider	559231 Y
UNII	42M2Y6NU9O Y
KEGG	D07937 Y
ChEBI	CHEBI:4912 N
ChEMBL	CHEMBL287413 N
ECHA InfoCard	100.035.017
Chemical and physical data
Formula	C25H33NO4
Molar mass	411.53 g/mol
3D model (Jmol)	Interactive image
SMILES C[C@@](O)(CCC)[C@H]1C[C@]64C=C[C@]1(OC)[C@@H]5Oc3c(O)ccc2C[C@H]6N(C)CC[C@@]45c23
InChI InChI=1S/C25H33NO4/c1-5-8-22(2,28)17-14-23-9-10-25(17,29-4)21-24(23)11-12-26(3)18(23)13-15-6-7-16(27)20(30-21)19(15)24/h6-7,9-10,17-18,21,27-28H,5,8,11-14H2,1-4H3/t17-,18-,21-,22-,23-,24+,25-/m1/s1 Y Key:CAHCBJPUTCKATP-FAWZKKEFSA-N Y
NY (what is this?)

Etorphine (M99) is a semi-synthetic opioid possessing an analgesic potency approximately 1,000–3,000 times that of morphine. It was first prepared in 1960 from oripavine, which does not generally occur in opium poppy extract but rather in "poppy straw" and in the related plants Papaver orientale and Papaver bracteatum. It was later reproduced in 1963 by a research group at MacFarlan Smith in Gorgie, Edinburgh, led by Professor Kenneth Bentley. It can also be produced from thebaine.

Etorphine is available legally only for veterinary use and is strictly governed by law. It is often used to immobilize elephants and other large mammals. Diprenorphine (M5050), also known as Revivon, is an opioid receptor antagonist that can be administered in proportion to the amount of etorphine used (1.3 times) to reverse its effects. Veterinary-strength etorphine is fatal to humans. For this reason the package as supplied to vets always includes the human antidote as well as etorphine.

The human antidote is generally naloxone, not diprenorphine, and is always prepared before the preparation of etorphine to be immediately administered following accidental human exposure to etorphine. The LD50 in humans is 30 μg which led to the requirement that the medicine include an equal dose of an antidote, diprenorphine or naloxone.

One of its main advantages is its speed of operation and, more importantly, the speed with which diprenorphine reverses the effects. The high incidence of side-effects, including severe cardiopulmonary depression, has caused etorphine to fall into disfavor in general veterinary practice. However, its high potency combined with the rapid action of both etorphine and its antagonist, diprenorphine, means that it has found a place for capture of large mammals such as rhinoceroses and elephants; under these circumstances both rapid onset and rapid recovery are very important characteristics. The high potency of etorphine means that sufficient etorphine can be administered to large wild mammals by projectile syringe (dart).