:IBNtxA

{{Short description|Chemical compound}}

{{Drugbox

| IUPAC_name = N-[(4R,4aS,7R,7aR,12bS)-3-(cyclopropylmethyl)-4a,9-dihydroxy-1,2,4,5,6,7,7a,13-octahydro-4,12-methanobenzofuro[3,2-e]isoquinoline-7-yl]-3-iodobenzamide

| image = IBNtxA Structure.svg

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| CAS_number =1314879-44-1

| ATC_prefix = none

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| PubChem = 51003467

| ChemSpiderID = 26617995

| ChEMBL = 1795711

| C=27 | H=29 | I=1 | N=2 | O=4

| smiles = C1C[C@]2([C@H]3CC4=C5[C@@]2(CCN3CC6CC6)[C@H]([C@@H]1NC(=O)C7=CC(=CC=C7)I)OC5=C(C=C4)O)O

| StdInChI = 1S/C27H29IN2O4/c28-18-3-1-2-17(12-18)25(32)29-19-8-9-27(33)21-13-16-6-7-20(31)23-22(16)26(27,24(19)34-23)10-11-30(21)14-15-4-5-15/h1-3,6-7,12,15,19,21,24,31,33H,4-5,8-11,13-14H2,(H,29,32)/t19-,21-,24+,26+,27-/m1/s1

| StdInChIKey = FGAFDGWRFOJPRY-XGTKUTNFSA-N

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IBNtxA, or 3-iodobenzoyl naltrexamine, is an atypical opioid analgesic drug derived from naltrexone. In animal studies it produces potent analgesic effects that are blocked by levallorphan{{cite journal |vauthors=Majumdar S, Subrath J, Le Rouzic V, Polikar L, Burgman M, Nagakura K, Ocampo J, Haselton N, Pasternak AR, Grinnell S, Pan YX, Pasternak GW |title=Synthesis and evaluation of aryl-naloxamide opiate analgesics targeting truncated exon 11-associated μ opioid receptor (MOR-1) splice variants |journal=J. Med. Chem. |volume=55 |issue=14 |pages=6352–62 |year=2012 |pmid=22734622 |pmc=3412067 |doi=10.1021/jm300305c }} and so appear to be μ-opioid mediated, but it fails to produce constipation or respiratory depression, and is neither rewarding or aversive{{cite journal | pmid = 22106286 | doi=10.1073/pnas.1115231108 | volume=108 | issue=49 | title=Truncated G protein-coupled mu opioid receptor MOR-1 splice variants are targets for highly potent opioid analgesics lacking side effects | pmc=3241767 | date=December 2011 | journal=Proc. Natl. Acad. Sci. U.S.A. | pages=19778–83 | vauthors=Majumdar S, Grinnell S, Le Rouzic V | bibcode=2011PNAS..10819778M | display-authors = etal | doi-access=free }} in conditioned place preference protocols.{{cite journal |vauthors=Grinnell SG, Majumdar S, Narayan A, Le Rouzic V, Ansonoff M, Pintar JE, Pasternak GW |title=Pharmacologic characterization in the rat of a potent analgesic lacking respiratory depression, IBNtxA |journal=J. Pharmacol. Exp. Ther. |volume=350 |issue=3 |pages=710–8 |year=2014 |pmid=24970924 |doi=10.1124/jpet.114.213199 |pmc=4152881}} These unusual properties are thought to result from agonist action at a splice variant or heterodimer of the μ-opioid receptor,{{cite journal |vauthors=Wieskopf JS, Pan YX, Marcovitz J, Tuttle AH, Majumdar S, Pidakala J, Pasternak GW, Mogil JS |title=Broad-spectrum analgesic efficacy of IBNtxA is mediated by exon 11-associated splice variants of the mu-opioid receptor gene |journal=Pain |volume=155 |issue=10 |pages=2063–70 |year=2014 |pmid=25093831 |doi=10.1016/j.pain.2014.07.014 |pmc=4372857}} rather than at the classical full length form targeted by conventional opioid drugs.Keck TM, Uddin MM, Babenko E, Wu C, Moura-Letts G. Abuse Liability and Anti-Addiction Potential of the Atypical Mu Opioid Receptor Agonist IBNtxA. The FASEB Journal 31 (1 Supplement), 985.4-985.4, 2017

In the Radioligand binding assay it has shown to have affinities of 0.11nM at the MOR, 0.24nM at the DOR and 0.03nM at the KOR and in the Hot- Plate Assay it is shown to be around 20x more potent than morphine. Azido Aryl Analogues of IBNtxA retain significant activity at the MOR.{{cite journal |vauthors=Grinnell SG, Rajendra U|title=Synthesis and Characterization of Azido Aryl Analogs of IBNtxA for Radio-Photoaffinity Labeling Opioid Receptors in Cell Lines and in Mouse Brain |journal=Cell Mol Neurobiology |volume=5 |issue=41 |pages=977–993 |year=2021 |pmid=32424771 |pmc=7671950 |doi=10.1007/s10571-020-00867-6}}