science

Iso-LSD

Iso-LSD is a science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Iso-LSD rather than just read about it. In short: Iso-LSD, also known as d-iso-LSD, (+)-iso-LSD, or (5R-8S)-LSD, as well as N,N-diethylisolysergamide, is a serotonin receptor modulator of the lysergamide family related to lysergic acid diethylamide (LSD). It is the 8-position epimer of LSD, with iso-LSD being 8α (8S) and LSD being 8β (8R).

Key takeaways

Iso-LSD belongs to science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Iso-LSD to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Iso-LSD from memory before moving on to harder problems.

Reference excerpt

Iso-LSD, also known as d-iso-LSD, (+)-iso-LSD, or (5R-8S)-LSD, as well as N,N-diethylisolysergamide, is a serotonin receptor modulator of the lysergamide family related to lysergic acid diethylamide (LSD). It is the 8-position epimer of LSD, with iso-LSD being 8α (8S) and LSD being 8β (8R). Iso-LSD is also the N,N-diethyl derivative of isoergine (isolysergic acid amide; iso-LSA), a constituent found in morning glory seeds. Iso-LSD is one of four possible stereoisomers of LSD.

Use and effects According to Albert Hofmann and colleagues, iso-LSD is inactive as a psychedelic in humans at doses of up to 500 μg, which is up to 25 times the minimum given doses of LSD (i.e., 20–50 μg). In other sources, iso-LSD was also stated as being inactive at doses of up to 50 μg/kg (3.5 mg for a 70-kg person), whereas LSD is active at a dose of 1 μg/kg (70 μg for a 70-kg person). Hence, iso-LSD is inactive in humans at doses of up to 50 times those of a common psychedelic dose of LSD and at doses of up to 175 times the minimum dose of LSD. Alexander Shulgin has additionally reported that iso-LSD was inactive at a dose of 4 mg orally. The related drug isoergine is known to be active in terms of psychoactive and hallucinogenic effects at doses of 2 to 5 mg orally.

Pharmacology

Pharmacodynamics Iso-LSD shows significant affinity for serotonin receptors. It had an affinity (IC50Tooltip half-maximal inhibitory concentration) of about 200 nM for serotonin receptors in rat brain membranes. For comparison, LSD had an affinity of about 8 to 10 nM in the studies, while isoergine had an affinity of 100 to 200 nM and ergine (LSA) had an affinity of about 200 nM. Hence, iso-LSD showed about 10- to 30-fold lower affinity for serotonin receptors than LSD but had similar affinity for the receptors as ergine and isoergine. Despite these findings however, iso-LSD showed only 0.12% of the antiserotonergic activity of LSD (~1,000-fold lower in comparison) in the isolated rat uterus. In studies by David E. Nichols and colleagues, iso-LSD fully substituted for LSD in rodent drug discrimination tests. Full substitution occurred at a dose of 0.32 mg/kg and its ED50Tooltip median effective dose was 0.14 mg/kg, whereas the LSD training dose was 0.08 mg/kg. Iso-LSD was about 7 times less potent than LSD in terms of ED50 in this assay. In other studies, the drug had about 3.7% of the toxic potency of LSD in rabbits (presumably in terms of LD50Tooltip median lethal dose) and, unlike LSD, was not pyretogenic.

Pharmacokinetics Iso-LSD is said to have identical metabolism to LSD. It has a longer elimination half-life than LSD. Iso-LSD's half-life was 12 hours while LSD's half-life was 4.2 hours.

Chemistry

The LSD molecule has two chiral centers at carbons 5 and 8 of the ergoline ring system and hence there are four possible enantiomeric stereoisomers of LSD. Iso-LSD, also known as d-iso-LSD, (+)-iso-LSD, or (5R-8S)-LSD, is one of four possible stereoisomers. The other isomers are LSD (d-LSD, (+)-LSD, or (5R,8R)-LSD), l-iso-LSD ((–)-iso-LSD or (5S,8R)-iso-LSD), and l-LSD ((–)-LSD or (5S,8S)-LSD). None of them are known to have significant psychoactivity in humans besides LSD. LSD is easily epimerized into iso-LSD with base. Consequently, iso-LSD is a common synthetic contaminant in chemical synthesis of LSD. Iso-LSD can be easily epimerized back into LSD. LSD can degrade into iso-LSD depending on temperature, solvent and pH, among other factors. In clinical studies, up to 30% of LSD administered in capsules has been found to isomerize into iso-LSD. Iso-LSD is said to be a metabolite of LSD in animals and humans. However, according to other sources, iso-LSD not a metabolite of LSD but is instead only a contaminant.

History Iso-LSD was first described in the scientific literature, by Albert Hofmann and colleagues, in the 1940s. The psychedelic effects of LSD were discovered by Hofmann in 1943 when he was using column chromatography to separate LSD from iso-LSD that had resulted as an impurity during the synthesis of LSD.

See also Substituted lysergamide Lumi-LSD

References

External links d-iso-LSD - Isomer Design LSD-25 (Discusses d-Iso-LSD) - TiHKAL - Erowid LSD-25 (Discusses d-Iso-LSD) - TiHKAL - Isomer Design

Illustrations

Worked examples

Example 1 — a first encounter with Iso-LSD

Start with the simplest possible case. Write down what Iso-LSD claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Iso-LSD before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Iso-LSD ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Iso-LSD

In research: Iso-LSD appears in science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Iso-LSD in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Iso-LSD is common in secondary-school and first-year university syllabi. It links to neighbouring topics David E. Nichols, Diethylamides, Drugs not assigned an ATC code, so understanding it makes those chapters shorter.
In everyday life: Look for Iso-LSD outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Iso-LSD in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Iso-LSD means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Iso-LSD out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Iso-LSD in simple terms?

Why does Iso-LSD matter?

Because it connects several science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Iso-LSD?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Iso-LSD.