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Lysergic acid 2-butyl amide

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Lysergic acid 2-butyl amide
Clinical data
Other names(6aR,9R)- N- (R)- 2-butyl- 7-methyl- 4,6,6a,7,8,9- hexahydroindolo- [4,3-fg] quinoline- 9-carboxamide
Legal status
Legal status
  • (8β)-6-Methyl-N-[(1R)-1-methylpropyl]-9,10-didehydroergoline-8-carboxamide
CAS Number
  • 137765-82-3 checkY (R,R) isomer, freebase
    137765-83-4 (R,R) isomer, maleate salt
PubChem CID
CompTox Dashboard (EPA)
Chemical and physical data
Molar mass323.440 g·mol−1
3D model (JSmol)
  • CN1C[C@@H](C(N[C@H](C)CC)=O)C=C2C1CC3=CNC4=C3C2=CC=C4
  • InChI=1S/C20H25N3O/c1-4-12(2)22-20(24)14-8-16-15-6-5-7-17-19(15)13(10-21-17)9-18(16)23(3)11-14/h5-8,10,12,14,18,21H,4,9,11H2,1-3H3,(H,22,24)/t12-,14-,18-/m1/s1 ☒N
 ☒NcheckY (what is this?)  (verify)

Lysergic acid 2-butyl amide (2-Butyllysergamide, LSB) is an analogue of LSD originally developed by Richard Pioch at Eli Lilly in the 1950s,[2] but mostly publicised through research conducted by the team led by David E. Nichols at Purdue University. It is a structural isomer of LSD, with the two ethyl groups on the amide nitrogen having been replaced by a single sec-butyl group, joined at the 2-position.[3] It is one of the few lysergamide derivatives to exceed the potency of LSD in animal drug discrimination assays, with the (R) isomer having an ED50 of 33nmol/kg for producing drug-appropriate responding, vs 48nmol/kg for LSD itself. The corresponding (R)-2-pentyl analogue has higher binding affinity for the 5-HT1A and 5-HT2A receptors, but is less potent in producing drug-appropriate responding, suggesting that the butyl compound has a higher efficacy at the receptor target.[4] The drug discrimination assay for LSD in rats involves both 5-HT1A and 5-HT2A mediated components, and while lysergic acid 2-butyl amide is more potent than LSD as a 5-HT1A agonist, it is slightly less potent as a 5-HT2A agonist, and so would probably be slightly less potent than LSD as a hallucinogen in humans. The main use for this drug has been in studies of the binding site at the 5-HT2A receptor through which LSD exerts most of its pharmacological effects,[5] with the stereoselective activity of these unsymmetric monoalkyl lysergamides foreshadowing the subsequent development of compounds such as lysergic acid 2,4-dimethylazetidide (LSZ).

See also



  1. ^ "Arrêté du 20 mai 2021 modifiant l'arrêté du 22 février 1990 fixant la liste des substances classées comme stupéfiants". www.legifrance.gouv.fr (in French). 20 May 2021.
  2. ^ US patent 2997470, Richard P. Pioch, "LYSERGIC ACID AMIDES", published 1956-03-05, issued 1961-08-22 
  3. ^ Oberlender R, Pfaff RC, Johnson MP, Huang XM, Nichols DE (January 1992). "Stereoselective LSD-like activity in d-lysergic acid amides of (R)- and (S)-2-aminobutane". Journal of Medicinal Chemistry. 35 (2): 203–11. doi:10.1021/jm00080a001. PMID 1732537.
  4. ^ Monte AP, Marona-Lewicka D, Kanthasamy A, Sanders-Bush E, Nichols DE (March 1995). "Stereoselective LSD-like activity in a series of d-lysergic acid amides of (R)- and (S)-2-aminoalkanes". Journal of Medicinal Chemistry. 38 (6): 958–66. doi:10.1021/jm00006a015. PMID 7699712.
  5. ^ David E. Nichols. LSD and Its Lysergamide Cousins. The Heffter Review of Psychedelic Research. 2001;2:80-87.