1B-LSD

Discovery

1B-LSD appeared on the research chemical market in August 2016 with no prior history in the scientific literature.^[2] Its original synthesizer is unknown. The first analytical and behavioral characterization was published by Brandt and colleagues in 2019 as Part V of the "Return of the lysergamides" series in Drug Testing and Analysis, using a research sample sourced from Synex Synthetics BV in the Netherlands.^[2]

The N1-acyl lysergamide series

1B-LSD belongs to a series of N1-acylated LSD derivatives that appeared sequentially on the research chemical market, each bearing a different acyl chain at the indole nitrogen. The lineage begins with ALD-52 (acetyl, first synthesized in the 1950s),^[7][8] continues through 1P-LSD (propanoyl, circa 2013–2015)^[9] and 1B-LSD (butanoyl, 2016),^[2] and extends to 1CP-LSD (cyclopropanoyl), which provided the first direct evidence of LSD release from an N1-acyl derivative in human serum.^[10] The use of N1-alkylated lysergamide derivatives to circumvent scheduling was anticipated as early as 1988 in a Drug Enforcement Administration report.^[11]

Regulatory response

Germany explicitly controlled 1B-LSD under the Neue-psychoaktive-Stoffe-Gesetz (NpSG) in July 2019,^[11] and it falls under the United Kingdom's blanket Psychoactive Substances Act 2016. Each new N1-acyl variant appeared in jurisdictions where its predecessor had been controlled — a pattern of iterative circumvention and legislative response that defines this compound series.

Structural identity

1B-LSD (1-butanoyl-d-lysergic acid diethylamide) belongs to the ergoline lysergamide family — compounds built on a tetracyclic ergoline core with a diethylamide group at the C-9 position. Its defining feature is a butanoyl (four-carbon acyl) group at the indole nitrogen (N1), placing it between 1P-LSD (propanoyl, three carbons) and longer-chain analogs in the N1-acylated LSD series.^[2]

The systematic lengthening of the acyl chain across this series — from the two-carbon acetyl group of ALD-52 through propanoyl, butanoyl, hexanoyl,^[12] and dodecanoyl^[7] — has provided a framework for studying how substituent size affects hydrolysis rate and in vivo potency. 1B-LSD is a constitutional isomer of 1P-ETH-LAD, sharing the molecular formula C₂₄H₃₁N₃O₂ but differing in the location of its structural modifications.^[2]

Molecular properties

Stereochemistry

1B-LSD retains the two chirality centers of the ergoline scaffold at positions C-5 and C-8, in the (6aR,9R) configuration required for serotonin receptor binding. The mirror-image l-isomer is pharmacologically inactive. The butanoyl group at N1 introduces no additional stereocenters.

Physical properties

No published data exist for the melting point, solubility, or crystal structure of 1B-LSD in any salt or free-base form. The compound is distributed on blotter paper or as pellets.^[13] As with all lysergamides, it is expected to be sensitive to light, heat, and oxidation, requiring cool, dark, anhydrous storage.

Mechanism of action

1B-LSD functions as a prodrug of LSD. The butanoyl group at the indole nitrogen is cleaved by enzymes in the blood and tissues, releasing LSD as the active compound.^[2][1] This deacylation has been directly demonstrated for close structural relatives: high LSD plasma levels appear in rats after administration of ALD-52 and 1P-LSD,^[1] and 1CP-LSD releases LSD when incubated with human serum.^[10] ALD-52, the prototype of the series, is confirmed as a prodrug with hydrolysis to LSD responsible for its activity.^[7]

Direct deacylation data specific to 1B-LSD have not been published — prodrug status is strongly inferred from structural analogy and pharmacological profile but remains formally unconfirmed. inferred In its intact form, 1B-LSD shows substantially reduced receptor binding, weak or absent activity at serotonin receptors in functional assays, yet induces head twitches in mice with relatively high potency — a dissociation consistent with in vivo conversion to LSD as the active species.^[1]

LSD as active moiety

After conversion, the pharmacology is that of LSD. LSD acts primarily as a partial agonist at the serotonin 5-HT₂A receptor on cortical pyramidal neurons.^[3] It also engages a broad range of serotonin, dopamine, adrenergic, and histamine receptor subtypes.^[8] The psychedelic effects are 5-HT₂A-mediated: the selective antagonist ketanserin completely blocks all subjective effects of LSD in controlled human studies.^[5]

Structural studies have revealed why LSD's effects last so long: the receptor's extracellular loop folds over the binding pocket like a lid, trapping the molecule and prolonging its occupancy.^[14][15]

Pharmacokinetics

No human pharmacokinetic study exists for 1B-LSD. The compound is presumed to undergo oral absorption followed by enzymatic conversion to LSD, but the rate and efficiency of this conversion in humans are unknown.

LSD itself shows dose-proportional pharmacokinetics, reaching peak blood levels approximately 1–1.5 hours after oral administration.^[16][17] Its half-life ranges from roughly 3 to 5 hours.^[16][18]

LSD is broken down primarily by the liver enzyme CYP2D6.^[19][20] People who metabolize drugs slowly through this enzyme (CYP2D6 poor metabolizers) experience roughly 75% higher LSD exposure, with prolonged and intensified effects.^[19] The CYP2D6 inhibitor paroxetine increases LSD blood levels by approximately 1.4- to 1.5-fold.^[20]

Where it acts

No neuroimaging studies of 1B-LSD have been conducted. The following mechanisms are established for LSD and expected to apply via the prodrug conversion.

The cellular trigger is 5-HT₂A receptor activation on layer V pyramidal neurons in the cortex.^[3] This increases excitatory signaling and disrupts the thalamic gate that normally filters sensory input before it reaches conscious awareness. The result is a broadening of information flow — perceptual, emotional, and associative streams that are ordinarily separated become simultaneously accessible, producing the distortions, novel associations, and emotional intensification characteristic of the psychedelic state. LSD also reduces the coherence of the default mode network (DMN), a set of brain regions tied to the sense of self. The degree of DMN disruption tracks with the intensity of ego dissolution.^[3]

Why it matters

The leading explanatory framework — Relaxed Beliefs Under Psychedelics (REBUS) — proposes that psychedelics weaken the brain's established predictive models while amplifying incoming sensory signals. This flattening of the brain's inference hierarchy is thought to allow rigid beliefs to be revised, potentially explaining both the acute experience and lasting therapeutic effects observed in depression and addiction trials.

LSD and related psychedelics also promote structural brain changes — growth of new dendritic branches and synaptic connections — through signaling pathways involving BDNF and mTOR.^[21] These changes outlast the acute drug experience and may underlie the persistent psychological effects reported after a single dose.

Toxicity

LSD, the active moiety, is generally considered physiologically safe with no established lethal dose in humans.^[3]

Psychological risks

At doses equivalent to 200 µg LSD and above, significant anxiety and ego dissolution emerge as the primary dose-limiting psychological effects.^[5] Pre-existing anxiety and mental state at the time of ingestion are significant predictors of adverse outcomes.^[6]

Hallucinogen persisting perception disorder (HPPD) — persistent visual disturbances such as geometry, after-images, halos, and trailing phenomena without impaired reality testing — is documented with LSD-class substances. LSD is the most commonly reported cause in published HPPD case series.^[25] HPPD can persist for months to years; adolescent onset has been documented.^[26] No 1B-LSD-specific HPPD cases have been reported.

Tolerance and dependence

Tolerance develops almost immediately after a single dose through reduction in 5-HT₂A receptor density in the frontal cortex, detectable within 24 hours.^[4] Cross-tolerance occurs between serotonergic psychedelics via this shared mechanism.^[4] Community data indicate a tolerance half-life of approximately 6 days, with full reset in about 14 days.^[13]

Psychedelics are generally considered not to produce physical dependence or addiction.^[3] Rapid tolerance itself limits compulsive redosing — the same dose taken the following day produces markedly diminished effects. Substance use disorder reports associated with LSD have appeared in pharmacovigilance databases, though methodological limitations constrain their interpretation.^[27]

Drug interactions

Contraindications

Absolute contraindications include personal or family history of psychotic disorders and concurrent lithium use. Relative contraindications include bipolar disorder, conditions that lower seizure threshold, pregnancy, concurrent use of tramadol or other drugs with serotonin toxicity potential, and CYP2D6 poor metabolizer status — which substantially increases LSD exposure and may cause unexpectedly prolonged and intensified effects.^[19] No 1B-LSD-specific contraindication data exist; all are inferred from the LSD evidence base.

1B-LSD occupies an ambiguous international legal position. It is not scheduled by name under most national controlled substances legislation, but its structural relationship to LSD — a universally controlled substance — brings it within the scope of structural analog or blanket psychoactive substance laws in many jurisdictions. As of April 2026, no jurisdiction has scheduled 1B-LSD under traditional controlled substance schedules, though Germany has explicitly controlled it under novel psychoactive substance legislation since 2019.

citation needed

Legal status is based on web-retrieved sources and general legislative interpretation. Confirm current scheduling against official statutory documents before relying on this information.