science

XLR-11

XLR-11 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 XLR-11 rather than just read about it. In short: XLR-11 (5"-fluoro-UR-144 or 5F-UR-144) is a drug that acts as a potent agonist for the cannabinoid receptors CB1 and CB2 with EC50 values of 98 nM and 83 nM, respectively. It is a 3-(tetramethylcyclopropylmethanoyl)indole derivative related to compounds such as UR-144, A-796,260 and A-834,735, but it is not specifically listed in the patent or scientific literature alongside these other similar compounds, and appear…

Key takeaways

XLR-11 belongs to science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect XLR-11 to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of XLR-11 from memory before moving on to harder problems.

Reference excerpt

XLR-11 (5"-fluoro-UR-144 or 5F-UR-144) is a drug that acts as a potent agonist for the cannabinoid receptors CB1 and CB2 with EC50 values of 98 nM and 83 nM, respectively. It is a 3-(tetramethylcyclopropylmethanoyl)indole derivative related to compounds such as UR-144, A-796,260 and A-834,735, but it is not specifically listed in the patent or scientific literature alongside these other similar compounds, and appears to have not previously been made by Abbott Laboratories, despite falling within the claims of patent WO 2006/069196. XLR-11 was found to produce rapid, short-lived hypothermic effects in rats at doses of 3 mg/kg and 10 mg/kg, suggesting that it is of comparable potency to APICA and STS-135.

Detection A forensic standard for this compound is available, and a representative mass spectrum has been posted on Forendex.

Recreational use XLR-11 was instead first identified by laboratories in 2012 as an ingredient in synthetic cannabis smoking blends, and appears to be a novel compound invented specifically for grey-market recreational use.

Legal Status XLR-11 was banned in New Zealand by being added to the temporary class drug schedule, as of 13 July 2012. The U.S. Drug Enforcement Administration (DEA) made XLR11 illegal under the Federal Controlled Substances act for the foreseeable future as of January 2024. It has also been banned in Florida as of 11 December 2012. Arizona banned XLR-11 on 3 April 2013. As of October 2015, XLR-11 is a controlled substance in China. XLR-11 is banned in the Czech Republic.

Side effects XLR-11 has been linked to hospitalizations due to its use.

Toxicity XLR-11 has been linked to acute kidney injury in some users, along with AM-2201.

See also FAB-144 JWH-018 STS-135 UR-144 XLR-12

References

Illustrations

Worked examples

Example 1 — a first encounter with XLR-11

Start with the simplest possible case. Write down what XLR-11 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 XLR-11 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 XLR-11 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 XLR-11

In research: XLR-11 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 XLR-11 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: XLR-11 is common in secondary-school and first-year university syllabi. It links to neighbouring topics Cannabinoids, Cyclopropanes, Designer drugs, so understanding it makes those chapters shorter.
In everyday life: Look for XLR-11 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 XLR-11 in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what XLR-11 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 XLR-11 out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is XLR-11 in simple terms?

Why does XLR-11 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 XLR-11?

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 XLR-11.