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Levomethadone
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Levomethadone

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Levomethadone
Levomethadone structure.svg
Levomethadone-xtal-1974-ball-and-stick.png
Clinical data
Other names Levamethadone; l-Methadone; 6R-Methadone; (–)-Methadone; R-(–)-Methadone; D-(–)-Methadone
AHFS/Drugs.com International Drug Names
Routes of
administration
By mouth, IV, IM, SC, IT
ATC code
Legal status
Legal status
Pharmacokinetic data
Bioavailability High
Protein binding 60–90%
Elimination half-life ~18 hours
Identifiers
  • (6R)-6-(dimethylamino)-4,4-diphenyl-3-heptanone
CAS Number
PubChem CID
ChemSpider
UNII
KEGG
ChEBI
ChEMBL
ECHA InfoCard 100.120.592
Chemical and physical data
Formula C21H27NO
Molar mass 309.453 g·mol−1
3D model (JSmol)
Melting point 99.5 °C (211.1 °F)
Solubility in water 48.48 mg/mL (20 °C)
  • 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, sold under the brand name L-Polamidon among others, is a synthetic opioid analgesic and antitussive which is marketed in Europe and is used for pain management and in opioid maintenance therapy. In addition to being used as a pharmaceutical drug itself, levomethadone is the main therapeutic component of methadone.

Levomethadone is used for narcotic maintenance in place of, or in some cases alongside as an alternative, to racemic methadone, owing to concern about the cardiotoxic and QT-prolonging action of racemic methadone being exclusively caused by the dextrorotatory enantiomer, dextromethadone.

Pharmacology

Pharmacodynamics

Levomethadone has approximately 50x the potency of the S-(+)-enantiomer as well as greater μ-opioid receptor selectivity. Accordingly, it is about twice as potent as methadone by weight and its effects are virtually identical in comparison. 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 and as a potent noncompetitive antagonist of the α3β4 nicotinic acetylcholine (nACh) receptor.

Receptor binding affinities of isomers of methadone
Compound Affinities (Ki, in nM) Ratios
MOR DOR KOR SERT NET NMDAR M:D:K SERT:NET
Racemic methadone 1.7 435 405 1,400 259 2,500–8,300 1:256:238 1:5
Dextromethadone 19.7 960 1,370 992 12,700 2,600–7,400 1:49:70 1:13
Levomethadone 0.945 371 1,860 14.1 702 2,800–3,400 1:393:1968 1:50

Chemistry

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 Levomethadone can easily be retrieved from the mother liquor in a high state of optical purity."

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

Society and culture

Generic names

Levomethadone is the generic name of the drug and its INN.

Brand names

Levomethadone has been sold under brand names including L-Polaflux, L-Polamidon, L-Polamivet, Levadone, Levo-Methasan, Levothyl, Mevodict, Levopidon and Vistadict, among others.

Legal 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. It is similarly controlled under the German Betäubungsmittelgesetz and similar laws in practically every other country.


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