PRO-LAD, or 6-propyl-6-nor-LSD, is a lysergamide related to LSD. It differs by replacing the N6-methyl group with a straight-chain propyl group. The compound was developed during medicinal-chemistry research on N6-substituted lysergamides in the 1980s. Animal drug-discrimination studies and historical human observations indicate LSD-like activity, although modern controlled clinical research is lacking.
Chemistry and history
PRO-LAD retains the ergoline skeleton and N,N-diethylamide group of LSD. Its N6-propyl substituent makes it part of the 6-norlysergamide series, alongside AL-LAD and ETH-LAD. It is distinct from PARGY-LAD, which carries a propynyl rather than propyl group.
A 1985 study synthesised a series of N6-alkyl norlysergic acid diethylamides and tested them in rats trained to discriminate LSD from saline. PRO-LAD was among the compounds that produced LSD-like stimulus effects (Hoffman and Nichols, 1985).
Pharmacology
Later structure–activity reviews reported that PRO-LAD substituted for LSD in trained animals with potency comparable to the parent compound. Historical human observations also described psychedelic effects. A 1986 review concluded that selected N6-ethyl, allyl and propyl analogues retained substantial activity, whereas longer N6-alkyl groups were associated with a marked reduction in activity (Nichols, Studies of the relationship between molecular structure and hallucinogenic activity, 1986).
These findings establish LSD-like pharmacological activity, without providing a modern receptor profile specific to PRO-LAD. The early studies predate current approaches to measuring functional selectivity at cloned human serotonin receptors.
Reported effects and human evidence
Descriptions of PRO-LAD in historical sources and personal reports mention changes in visual perception, thought and mood. The human evidence is not based on contemporary controlled trials, and the available accounts establish neither the frequency of adverse reactions nor a reliable duration of effects.
Research limitations
PRO-LAD has more historical pharmacological evidence than many newer lysergamides, but its human pharmacokinetics, acute toxic range, dependence potential and long-term effects remain poorly characterised. Animal drug-discrimination results and older human accounts cannot establish safety on their own.
Related lysergamides
PRO-LAD is related to AL-LAD, ETH-LAD, PARGY-LAD and LSD. Its N6-propyl group distinguishes it from the allyl, ethyl and propynyl analogues.
