Naltrindole

Naltrindole is a highly potent, highly selective delta opioid receptor antagonist used in biomedical research. In May 2012 a paper was published in Nature with the structure of naltrindole in complex with the mouse δ-opioid G-protein coupled receptor, solved by X-ray crystallography.^[1]

Naltrindole

Clinical data
Routes of administration	IV
ATC code	none
Identifiers
IUPAC name 17-Cyclopropylmethyl-6,7-dehydro-4,5-epoxy -3,14-dihydroxy-6,7,2',3'-indolomorphinan
CAS Number	111555-53-4
PubChem CID	5497186
IUPHAR/BPS	1641
ChemSpider	4593753 Y
UNII	G167Z38QA4
ChEMBL	ChEMBL567175 Y
CompTox Dashboard (EPA)	DTXSID60912216
Chemical and physical data
Formula	C26H26N2O3
Molar mass	414.505 g·mol−1
3D model (JSmol)	Interactive image
SMILES Oc4c3O[C@H]7c2c(c1ccccc1[nH]2)C[C@@]6(O)[C@H]5N(CC[C@@]67c3c(cc4)C5)CC8CC8
InChI InChI=1S/C26H26N2O3/c29-19-8-7-15-11-20-26(30)12-17-16-3-1-2-4-18(16)27-22(17)24-25(26,21(15)23(19)31-24)9-10-28(20)13-14-5-6-14/h1-4,7-8,14,20,24,27,29-30H,5-6,9-13H2/t20-,24+,25+,26-/m1/s1 Y Key:WIYUZYBFCWCCQJ-IFKAHUTRSA-N Y
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Drug design

Since peptide compounds are unable to cross the blood–brain barrier, researchers developed naltrindole to be a non-peptide antagonist analog of the delta-preferring endogenous opiate enkephalin. Enkephalin contains an aromatic phenyl group on its Phe⁴ residue, which was hypothesized to be the "address" sequence responsible for the opiate's delta opioid receptor affinity.^[2] Thus, attachment of a phenyl-containing indole molecule to the C-ring of naltrexone's morphinan base successfully produced a drug with the high receptor affinity of naltrexone, but which binds almost exclusively to the delta opioid receptor.^[3]