Levomethadone

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Levomethadone
Levomethadone structure.svg
Systematic (IUPAC) name
(6R)-6-(dimethylamino)-4,4-diphenyl-3-heptanone
Clinical data
AHFS/Drugs.com International Drug Names
Legal status
Routes of
administration
Oral, IV, IM, SC, IT[1]
Pharmacokinetic data
Bioavailability High[1]
Protein binding 60-90%[1]
Biological half-life ~18 hours[1]
Identifiers
CAS Number 125-58-6
Template:CAS (HCl)
ATC code N07BC05 (WHO)
PubChem CID: 22267
ChemSpider 20904
Chemical data
Formula C21H27NO
Molecular mass 309.445 g/mol
  • O=C(C(c1ccccc1)(c2ccccc2)C[C@H](N(C)C)C)CC
  • InChI=1S/C21H27NO/c1-5-20(23)21(16-17(2)22(3)4,18-12-8-6-9-13-18)19-14-10-7-11-15-19/h6-15,17H,5,16H2,1-4H3/t17-/m1/s1
  • Key:USSIQXCVUWKGNF-QGZVFWFLSA-N

Levomethadone (INN; L-Polamidon, L-Polamivet, Levadone, Levothyl), or levamethadone, is a synthetic opioid analgesic and antitussive which is marketed in Europe and is used for pain management and in opioid maintenance therapy.[1][2][3] In addition to being used as a pharmaceutical drug itself, levomethadone, or R-(−)-methadone, is the active enantiomer of methadone,[2] having approximately 50x the potency of the S-(+)-enantiomer as well as greater μ-opioid receptor selectivity.[1][4] Accordingly, it is about twice as potent as methadone by weight and its effects are virtually identical in comparison.[5][6] In addition to its activity at the opioid receptors, levomethadone has been found to act as a weak competitive antagonist of the N-methyl-D-aspartate (NMDA) receptor complex[7] and as a potent noncompetitive antagonist of the α3β4 nicotinic acetylcholine (nACh) receptor.[8]

There is now an asymmetric synthesis[9] available to prepare both levomethadone [R-(−)-methadone] and dextromethadone [S-(+)-methadone].[10]

The separation of the stereoisomers is one of the easier in organic chemistry and is described in the original patent. It involves "treatment of racemic methadone base with d-(+)-tartaric acid in an acetone/water mixture [which] precipitates almost solely the dextro-methadone levo-tartrate, and the more potent levo-methadone can easily be retrieved from the mother liquor in a high state of optical purity" [11]

Regulatory status

Levomethadone is listed under the Single Convention On Narcotic Drugs 1961 and is a Schedule II Narcotic controlled substance in the US as an isomer of methadone (ACSCN 9250) and is not listed separately, nor is dextromethadone.[12] It is similarly controlled under the German Betäubungsmittelgesetz and similar laws in practically every other country.

See also

References

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  10. US patent 6143933 
  11. https://www.erowid.org/archive/rhodium/chemistry/methadone.html
  12. http://www.deadiversion.usdoj.gov/quotas/conv_factor/index.html