LSM-775

Discovery

LSM-775 was synthesized by Albert Hofmann at Sandoz Laboratories in Basel during the mid-1950s, part of a systematic program exploring lysergic acid amide structure-activity relationships.^[1][6] The first published human data appeared in 1957, when Gogerty and Dille reported that 75 µg produced roughly the same subjective response as 50 µg of LSD in two subjects, with shorter duration.^[3] Two additional small studies confirmed LSM-775 as approximately 5- to 10-fold less potent than LSD by weight and incapable of producing more than threshold psychedelic effects.^[1]

Institutional trajectory

Sandoz did not pursue LSM-775 commercially. Unlike LSD, which the company marketed as Delysid for psychiatric research, LSM-775's attenuated potency and unfavorable side-effect profile — sedation and nausea at effective doses — rendered it unsuitable for clinical development. No pharmaceutical company has investigated the compound in any therapeutic context, and it produced no discernible scientific or cultural impact during its initial era.

Modern era

LSM-775 reappeared in 2013 on the new psychoactive substances market, sold as a research chemical — presumably motivated by historical reports suggesting weak LSD-like effects.^[1] This emergence prompted the first modern pharmacological characterization by Brandt and colleagues in 2018, published as part of the "Return of the Lysergamides" research series — the only published investigation specific to LSM-775.^[1] The compound remains unscheduled in most jurisdictions and circulates in small quantities among research chemical users.

Structural class

LSM-775 belongs to the lysergamide family of ergoline derivatives, sharing the tetracyclic ergoline core with LSD, 1P-LSD, and AL-LAD. The defining structural modification is the replacement of LSD's N,N-diethylamide group at C-9 with a morpholine ring, forming a cyclic amide. This rigid ring constrains the spatial orientation of the amide nitrogen, directly altering how the molecule fits into serotonin receptor binding pockets.^[7]

Molecular identity

The core structure consists of four fused rings — the indole moiety (rings A and B), the cyclohexane ring (C), and the piperidine ring (D) — with a morpholine substituent at C-9. The morpholine ring contains an oxygen atom that introduces an additional hydrogen-bond acceptor site absent in LSD, contributing to the compound's somewhat lower lipophilicity.

Stereochemistry

LSM-775 has two chirality centers at C-6a and C-9, both in the R-configuration: (6aR,9R). This matches the pharmacologically active d-isomer series shared by LSD and other active lysergic acid derivatives. The absolute configuration has been confirmed by X-ray crystallography of the hemitartrate salt.^[1]

Structure-activity relationships

The morpholine substitution is the key structural determinant of LSM-775's pharmacological profile. LSD's flexible diethyl groups adopt specific conformations to optimally occupy the 5-HT₂A binding pocket;^[8] the rigid morpholine ring disrupts these interactions, reducing psychedelic potency while leaving 5-HT₁A activity relatively intact.^[7] The result is a compound that retains strong serotonergic activity but shifts the balance from hallucinogenic to sedative-somatic effects.

Mechanism of action

LSM-775 acts simultaneously at two serotonin receptor types with opposing functional consequences.^[1] At 5-HT₂A — the receptor responsible for psychedelic effects — it functions as a partial agonist, activating the receptor with reduced efficacy compared to LSD or serotonin. At 5-HT₁A, it functions as a full agonist with high potency, producing sedation and dampening the excitatory outputs of 5-HT₂A activation.

This dual action creates an unusual self-suppressing pharmacology: LSM-775's 5-HT₁A activity actively masks the psychedelic effects mediated by its own 5-HT₂A activity. In the standard animal model for hallucinogenic potential, LSM-775 alone produces no significant response — hallucinogenic-type behavior emerges only when 5-HT₁A receptors are pharmacologically blocked.^[1][2] This masking phenomenon parallels observations with 5-MeO-DMT^[2][9] and is analogous to the non-hallucinogenic 5-HT₂A agonist lisuride.^[10]

Despite sharing the ergoline scaffold with LSD — which binds dopamine D₂ receptors with high affinity^[8] — no published binding data confirm dopamine receptor activity for LSM-775.^[1] Dopamine receptor engagement is plausible but remains experimentally unconfirmed. inferred

Pharmacokinetics

No pharmacokinetic studies have been published for LSM-775 in any species. Absorption, distribution, metabolism, and elimination parameters are entirely uncharacterized.

By structural analogy with LSD, metabolism likely involves hepatic cytochrome enzymes, and poor metabolizers of related compounds show substantially higher plasma concentrations and prolonged effects.^[11] LSD's principal urinary metabolite is 2-oxo-3-hydroxy-LSD,^[12] and a similar pathway is plausible for LSM-775 but unmeasured.

Historical reports describe LSM-775's duration as shorter than LSD at equivalent subjective doses,^[3][4] suggesting either faster elimination or shorter receptor residence time, but neither parameter has been determined. Community-derived data suggest total duration of 6–10 hours with onset at 10–30 minutes by the oral route.^[13] inferred

No direct neuroimaging, electrophysiological, or neuroplasticity data have been published for LSM-775. The following discussion draws on class-level evidence from serotonergic psychedelics and LSM-775's specific pharmacological profile. inferred

Where it acts

Classical serotonergic psychedelics produce their effects through 5-HT₂A activation on pyramidal neurons in the prefrontal cortex, disrupting the brain's default filtering of sensory and cognitive input.^[14] LSM-775's partial 5-HT₂A agonism engages this pathway, but its concurrent full 5-HT₁A agonism introduces a countervailing brake — reducing neuronal firing rates in the cortex and dampening arousal circuits in the brainstem.

The behavioral evidence is stark: LSM-775 produces no head-twitch response in mice unless 5-HT₁A receptors are blocked first.^[1] The neural prediction is a partially engaged psychedelic state — some disruption of default mode network integrity and cortical synchronization, but substantially attenuated compared to compounds like LSD or psilocybin. The prominent sedation and nausea reported by users^[4] likely reflect 5-HT₁A-driven suppression of arousal and activation of brainstem emetic circuits.

Why it matters

The REBUS model (relaxed beliefs under psychedelics) predicts that psychedelics loosen rigid cognitive patterns by increasing cortical entropy through 5-HT₂A activation. LSM-775's 5-HT₁A suppression of 5-HT₂A output would constrain this entropy increase, predicting mild perceptual loosening without the full dissolution of conceptual boundaries seen with LSD or psilocybin.

Whether LSM-775 promotes neuroplasticity — dendritic growth and synapse formation, as documented for other 5-HT₂A agonists — is unknown. Whether partial agonists produce proportionally reduced neuroplastic effects is an open question in the field, and LSM-775 could serve as a useful test case.

Toxicity

No lethal dose has been established for LSM-775 in any species, and no controlled toxicity studies have been conducted.^[1] By class analogy, serotonergic psychedelics possess extremely wide safety margins in animal models, and no death attributable solely to LSD has been confirmed despite decades of widespread use.^[14] This general safety margin is expected to extend to LSM-775 but remains unconfirmed. safety citation needed

No case reports of overdose, hospitalization, or fatality involving LSM-775 have been published.

Psychological Risks

The standard psychological risk profile of serotonergic psychedelics applies: acute anxiety, confusion, thought loops, and challenging experiences may occur, particularly in unfavorable set and setting or in individuals with pre-existing psychiatric vulnerabilities. Risk of HPPD (HPPD) is a recognized class-level concern.^[15]

LSM-775's attenuated hallucinogenic potency may reduce the intensity of challenging perceptual experiences but does not eliminate psychological distress risk. The dominant 5-HT₁A component introduces a sedative, nauseogenic quality that could itself produce a dysphoric experience when combined with residual psychedelic effects.

Personal or family history of psychotic disorders, schizophrenia, or bipolar disorder constitutes a risk factor for acute psychiatric crisis with any serotonergic psychedelic.

Tolerance and Dependence

Serotonergic psychedelics produce rapid tolerance through downregulation, occurring within 24 hours of a single dose.^[5] Cross-tolerance between psychedelics operates through this shared mechanism.^[5] Community-derived data for LSM-775 report tolerance building almost immediately after ingestion, with a half-life of approximately 6 days and full reset at 14 days.^[13]

No abuse liability has been documented for LSM-775. Serotonergic psychedelics are generally considered non-addictive as a class.^[14] Rapid tolerance development mechanistically discourages compulsive redosing.

Drug Interactions

SSRIs, SNRIs, and MAOIs carry serotonin syndrome risk when combined with serotonergic psychedelics. A scoping review of antidepressant-psychedelic combinations found no confirmed serotonin syndrome cases in published clinical studies, though most studies excluded participants on serotonergic medications.^[17] SSRIs may also attenuate LSM-775's psychedelic effects.

MAOI combinations present the most severe theoretical risk: blocking serotonin breakdown could amplify LSM-775's serotonergic activity beyond safe levels.

Contraindications

Absolute contraindications:

• Psychotic disorders or personal history of psychosis — serotonergic psychedelics may trigger or worsen psychotic episodes.
• Concurrent MAOI use — risk of severe serotonin syndrome.
• Concurrent tramadol use — serotonin syndrome risk.^[16]

Relative contraindications:

• Bipolar disorder — risk of triggering manic episodes, particularly in bipolar I.
• Family history of psychotic disorders — elevated risk of psychedelic-triggered psychosis.
• Concurrent SSRI/SNRI use — theoretical serotonin syndrome risk, though confirmed cases are absent from the literature.^[17] Likely reduced psychedelic effects.
• Heart conditions — the pronounced cardiovascular effects (rapid heart rate, elevated blood pressure) documented in user reports^[4] suggest caution.
• Concurrent lithium use — seizure risk by class analogy with other lysergamides. citation needed

LSM-775 is not listed in the United Nations Convention on Psychotropic Substances (1971), and most jurisdictions have not enacted substance-specific controls. Where addressed, the compound falls under broad structural analog or novel psychoactive substance legislation rather than explicit scheduling.

Analogue act considerations

In the United States, the Federal Analogue Act extends Schedule I/II controls to substances "substantially similar" in structure or effect to a listed substance when intended for human consumption. LSM-775's relationship to LSD (Schedule I) makes analogue prosecution theoretically possible, but the morpholine substitution represents a significant structural departure from LSD's diethylamide group. Legal analysis suggests the compound occupies a grey area under current analogue law.^[18] No case law specific to LSM-775 prosecution under the Act has been identified.