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Systematic (IUPAC) name
Legal status
Legal status
  • Legal
CAS Number 2154-02-1
63937-57-5 (4'-nitromethopholine)
ATC code none
PubChem CID 16538
Chemical data
Formula C20H24ClNO2
Molar mass 345.87 g/mol[[Script error: No such module "String".]]
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Methopholine is an opioid analgesic drug invented in the 1960s.

Methopholine is an isoquinoline derivative which is not structurally related to most other opioids.[1] It has around the same efficacy as an analgesic as codeine, and was evaluated for the treatment of postoperative pain, but never commercialised.[2][3][4]

Methopholine has two enantiomers, with the levo (R) enantiomer being the active form, around 3x the potency of codeine, and the (S) enantiomer being inactive. Analogues where the 4'-chloro group has been replaced by other groups have also been tested, the fluoro derivative being slightly more potent than chloro, and the nitro derivative being most potent of all, with the racemic 4'-nitromethopholine being around 20x the potency of codeine.[5][6]


  1. Feinberg AP, Creese I, Snyder SH. The opiate receptor: a model explaining structure-activity relationships of opiate agonists and antagonists. Proceedings of the National Academy of Sciences U S A. 1976 Nov;73(11):4215-9.
  2. Moore J, Foldes FF, Davidson GM. An evaluation of the efficacy of methopholine for the relief of postoperative pain. American Journal of Medical Sciences. 1962 Sep;244:337-43.
  3. Cass LJ, Frederik WS. Methopholine, A New Analgesic Agent. American Journal of Medical Sciences. 1963 Nov;246:550-7.
  4. Sciorelli G. Plasma levels and renal excretion of unchanged methopholine in man. Experientia. 1967 Nov 15;23(11):934-6.
  5. Casy AF, Pargitt RY. Opioid analgesics, chemistry and receptors. 1986, Plenum Press, New York. p 390. ISBN 0306421305
  6. Walter M, Besendorf H, Schnider O. Synthesen in der Isochinolinreihe Substituierte 1-[ω-(Nitrophenyl)alkyl]-1,2,3,4-tetrahydro-isochinoline. Helvetica Chimica Acta. 1963;46(4):1127-1131.