Title: Etorphine
CAS Registry Number: 14521-96-1
CAS Name: [5a,7a(R)]-4,5-Epoxy-3-hydroxy-6-methoxy-a,17-dimethyl-a-propyl-6,14-ethenomorphinan-7-methanol
Additional Names: tetrahydro-7a-(1-hydroxy-1-methylbutyl)-6,14-endo-ethenooripavine; 7,8-dihydro-7a-[1(R)-hydroxy-1-methylbutyl]-O6-methyl-6,14-endo-ethenomorphine; 7a-[1(R)-hydroxy-1-methylbutyl]-6,14-endo-ethenotetrahydrooripavine; 19-propylorvinol; tetrahydro-7a-(2-hydroxy-2-pentyl)-6,14-endo-ethenooripavine
Molecular Formula: C25H33NO4
Molecular Weight: 411.53
Percent Composition: C 72.96%, H 8.08%, N 3.40%, O 15.55%
Literature References: Narcotic analgesic. Prepn: BE 618392; K. W. Bentley, GB 937214 (1962, 1963 both to J. F. MacFarlan); and structure: K. W. Bentley, D. G. Hardy, Proc. Chem. Soc. London 1963, 220. Improved prepn: W. R. Hydro, US 3763167 (1973 to U.S. Army). Determn by HPLC: I. Jane, A. McKinnon, J. Chromatogr. 323, 19 (1985). Analgesic activity: G. F. Blane, J. Pharm. Pharmacol. 19, 367 (1967). Pharmacology: Lister, ibid. 16, 364 (1964). Use as tranquilizer in dogs: J. L. Crooks et al., Vet. Rec. 87, 498 (1970); M. Grange et al., Rev. Med. Vet. 124, 899 (1973); in large animals: A. M. Harthoorn, J. Am. Vet. Med. Assoc. 149, 875 (1966); B. T. Alford et al., ibid. 164, 702 (1974).
Properties: White crystals from aqueous ethoxyethanol, mp 214-217°. (7b-isomer, melts at 280°).
Melting point: mp 214-217°; 7b-isomer, melts at 280°
Derivative Type: Hydrochloride
Manufacturers' Codes: M-99
Molecular Formula: C25H33NO4.HCl
Molecular Weight: 447.99
Percent Composition: C 67.03%, H 7.65%, N 3.13%, O 14.29%, Cl 7.91%
Properties: mp 266-267°. (7b-isomer hydrochloride, dec at 290)°.
Melting point: mp 266-267°
Derivative Type: Hydrochloride in combination with acepromazine
Trademarks: Immobilon (Reckitt & Colman)
Derivative Type: 3-Acetate
Additional Names: Acetorphine; O3-acetyl-7,8-dihydro-7a-[1(R)-hydroxy-1-methylbutyl]-O6-methyl-6,14-endo-ethenomorphine; 3-O-acetyl-7a-[1(R)-hydroxy-1-methylbutyl]-6,14-endo-ethenotetrahydrooripavine; 3-O-acetyl-17-propylorvinol
Molecular Formula: C27H35NO5
Molecular Weight: 453.57
Percent Composition: C 71.50%, H 7.78%, N 3.09%, O 17.64%
Properties: Crystals from methanol, mp 195°.
Melting point: mp 195°
Derivative Type: 3-Acetate hydrochloride
Manufacturers' Codes: M-183
Molecular Formula: C27H35NO5.HCl
Molecular Weight: 490.03
Percent Composition: C 66.18%, H 7.40%, N 2.86%, O 16.32%, Cl 7.23%
Properties: mp 206°.
Melting point: mp 206°
NOTE: Acetorphine and etorphine are controlled substances (opium derivatives): 21 CFR, 1308.11. Etorphine hydrochloride is a controlled substance (opiate): 21 CFR, 1308.12.
CAUTION: Use with extreme care; very small amounts may bring about respiratory paralysis and death: D. W. Upson, Upson's Handbook of Clinical Veterinary Pharmacology (VM Publishing, Bonner Springs, 1980) pp 380-381.
Therap-Cat-Vet: Used to immobilize large animals.
Etoxazole Etozolin Etretinate Etrimfos Etryptamine

Systematic (IUPAC) name
6,14-endoetheno – 7 a (1-(R)-hydroxy-1 methylbutyl)-tetrahydro-nororipavine
Clinical data
AHFS/ International Drug Names
Legal status Prohibited (S9) (AU) Narcotic Schedules I and IV (UN) List 1 (Netherlands)
Schedule I/II (see text) (United States)
CAS number 14521-96-1 N
ATCvet code QN02AE90
PubChem CID 644209
DrugBank DB01497
ChemSpider 559231 YesY
KEGG D07937 YesY
Chemical data
Formula C25H33NO4 
Mol. mass 411.53 g/mol
 N (what is this?)  (verify)

Etorphine (M99) is a semi-synthetic opioid possessing an analgesic potency approximately 1,000–3,000 times that of morphine.[1] 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.[2] It was later reproduced in 1963 by a research group at MacFarlan Smith in Gorgie, Edinburgh, led by Professor Kenneth Bentley.[3] It can also be produced from thebaine.[citation needed]