Metazocine

{{Short description|Opioid analgesic}}

{{Distinguish|Metazosin}}

{{Drugbox

| IUPAC_name = (2R,6R,11R)-3,6,11-Trimethyl-1,2,3,4,5,6-hexahydro-2,6-methanobenzo[d]azocin-8-ol

| image = metazocine.svg

| image_class = skin-invert-image

| tradename =

| pregnancy_category =

| legal_BR = A1

| legal_BR_comment = {{Cite web |author=Anvisa |author-link=Brazilian Health Regulatory Agency |date=2023-03-31 |title=RDC Nº 784 - Listas de Substâncias Entorpecentes, Psicotrópicas, Precursoras e Outras sob Controle Especial |trans-title=Collegiate Board Resolution No. 784 - Lists of Narcotic, Psychotropic, Precursor, and Other Substances under Special Control|url=https://www.in.gov.br/en/web/dou/-/resolucao-rdc-n-784-de-31-de-marco-de-2023-474904992 |url-status=live |archive-url=https://web.archive.org/web/20230803143925/https://www.in.gov.br/en/web/dou/-/resolucao-rdc-n-784-de-31-de-marco-de-2023-474904992 |archive-date=2023-08-03 |access-date=2023-08-16 |publisher=Diário Oficial da União |language=pt-BR |publication-date=2023-04-04}}

| legal_CA = Schedule I

| legal_US = Schedule II

| legal_DE = Anlage I

| routes_of_administration =

| bioavailability =

| metabolism =

| elimination_half-life =

| excretion =

| CAS_number_Ref = {{cascite|correct|CAS}}

| CAS_number = 3734-52-9

| ATC_prefix = none

| ATC_suffix =

| PubChem = 62518

| KEGG = C11789

| ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}

| ChemSpiderID = 56292

| UNII_Ref = {{fdacite|correct|FDA}}

| UNII = XD53YGT34W

| ChEMBL_Ref = {{ebicite|correct|EBI}}

| ChEMBL = 257661

| C=15 | H=21 | N=1 | O=1

| smiles = OC1=CC([C@@](C)([C@@]2([H])C)CCN(C)[C@]2([H])C3)=C3C=C1

| StdInChI_Ref = {{stdinchicite|correct|chemspider}}

| StdInChI = 1S/C15H21NO/c1-10-14-8-11-4-5-12(17)9-13(11)15(10,2)6-7-16(14)3/h4-5,9-10,14,17H,6-8H2,1-3H3

| StdInChIKey_Ref = {{stdinchicite|correct|chemspider}}

| StdInChIKey = YGSVZRIZCHZUHB-UHFFFAOYSA-N

}}

Metazocine is an opioid analgesic related to pentazocine. While metazocine has significant analgesic effects,{{cite journal | vauthors = Hori M, Ban M, Imai E, Iwata N, Suzuki Y, Baba Y, Morita T, Fujimura H, Nozaki M, Niwa M | title = Novel nonnarcotic analgesics with an improved therapeutic ratio. Structure-activity relationships of 8-(methylthio)- and 8-(acylthio)-1,2,3,4,5,6-hexahydro-2,6-methano-3-benzazocines | journal = Journal of Medicinal Chemistry | volume = 28 | issue = 11 | pages = 1656–61 | date = November 1985 | pmid = 2999399 | doi = 10.1021/jm00149a020 }} mediated through a mixed agonist–antagonist action{{cite journal | vauthors = Berzetei-Gurske I, Loew GH | title = The novel antagonist profile of (-)metazocine | journal = Progress in Clinical and Biological Research | volume = 328 | pages = 33–6 | date = 1990 | pmid = 2154788 }} at the mu opioid receptor,{{cite journal | vauthors = Gharagozlou P, Demirci H, David Clark J, Lameh J | title = Activity of opioid ligands in cells expressing cloned mu opioid receptors | journal = BMC Pharmacology | volume = 3 | pages = 1 | date = January 2003 | pmid = 12513698 | pmc = 140036 | doi = 10.1186/1471-2210-3-1 | doi-access = free }} its clinical use is limited by dysphoric and hallucinogenic effects which are most likely caused by activity at kappa opioid receptors (where it is a high-efficacy agonist){{cite journal | vauthors = Gharagozlou P, Hashemi E, DeLorey TM, Clark JD, Lameh J | title = Pharmacological profiles of opioid ligands at kappa opioid receptors | journal = BMC Pharmacology | volume = 6 | pages = 3 | date = January 2006 | pmid = 16433932 | pmc = 1403760 | doi = 10.1186/1471-2210-6-3 | doi-access = free }} and/or sigma receptors.{{cite journal | vauthors = Shannon HE | title = Pharmacological analysis of the phencyclidine-like discriminative stimulus properties of narcotic derivatives in rats | journal = The Journal of Pharmacology and Experimental Therapeutics | volume = 222 | issue = 1 | pages = 146–51 | date = July 1982 | doi = 10.1016/S0022-3565(25)33166-6 | pmid = 7086696 }}{{cite journal | vauthors = Slifer BL, Balster RL, May EL | title = Reinforcing and phencyclidine-like stimulus properties of enantiomers of metazocine | journal = Pharmacology, Biochemistry, and Behavior | volume = 25 | issue = 4 | pages = 785–9 | date = October 1986 | pmid = 3786338 | doi = 10.1016/0091-3057(86)90388-6 | s2cid = 32126170 }}

Metazocine is in Schedule II of the Controlled Substances Act 1970 of the United States as a Narcotic with ACSCN 9240 with a 19 gram aggregate manufacturing quota as of 2014. The free base conversion ratio for salts includes 0.81 for the hydrochloride and 0.74 for the hydrobromide.{{cite web | title = Quotas - 2014 | url = http://www.deadiversion.usdoj.gov/fed_regs/quotas/2014/fr0825.htm | work = Diversion Control Division | publisher = U.S. Department of Justice, Drug Enforcement Administration }} It is listed under the Single Convention for the Control of Narcotic Substances 1961 and is controlled in most countries in the same fashion as is morphine.