Lysergic acid 3-pentyl amide (3-Pentyllysergamide, LSP) is an analogue of LSD originally researched by David E. Nichols and colleagues at Purdue University. It has similar binding affinity to LSD itself as both a 5-HT1A and 5-HT2A agonist, and produces similar behavioral and physiological responses in animals with only slightly lower potency than LSD. Other isomers of this compound have also been explored, with the 1-pentylamide being around 75% the potency of LSD, while the (R)-2-pentylamide shows similar 5-HT2A binding affinity to LSD in vitro but has only around half the potency of LSD in producing drug-appropriate responding in mice, and the (S)-2-pentylamide is inactive.
^David E. Nichols. LSD and Its Lysergamide Cousins. The Heffter Review of Psychedelic Research. 2001;2:80-87.
^Monte AP, Marona-Lewicka D, Kanthasamy A, Sanders-Bush E, Nichols DE. Stereoselective LSD-like activity in a series of d-lysergic acid amides of (R)- and (S)-2-aminoalkanes. Journal of Medicinal Chemistry. 1995 Mar 17;38(6):958-66. doi:10.1021/jm00006a015PMID7699712