chemistry

Ketobemidone

Ketobemidone is a chemistry 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 Ketobemidone rather than just read about it. In short: Ketobemidone, sold under the brand name Ketogan (a mixture of ketobemidone and Spasmolytic A29) among others, is a powerful synthetic opioid painkiller. Its effectiveness against pain is in the same range as morphine, and it also has some NMDA-antagonist properties imparted, in part, by its metabolite norketobemidone.

Key takeaways

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

Reference excerpt

Ketobemidone, sold under the brand name Ketogan (a mixture of ketobemidone and Spasmolytic A29) among others, is a powerful synthetic opioid painkiller. Its effectiveness against pain is in the same range as morphine, and it also has some NMDA-antagonist properties imparted, in part, by its metabolite norketobemidone. This may make it useful for some types of pain that do not respond well to other opioids. It is marketed in Denmark, Iceland, Norway. Until 2024 it was available in, but is now withdrawn in Sweden. It is used for severe pain.

History Ketobemidone was first synthesized in 1942 by Eisleb and colleagues, at the laboratory of I.G. Farbenindustrie at Hoechst during the Second World War. The first study of it in humans was published in 1946, and it was introduced in clinical medicine shortly after. It was not in clinical use in the United States when the Controlled Substances Act 1970 was promulgated and was assigned to Schedule I with an ACSCN of 9628. As of 2013, no annual manufacturing quota was assigned by the DEA. Pfizer manufactures ketobemidone under the tradenames Ketogan and Ketorax. It is available as tablets, suppositories, and injection fluid. A sustained release formulation, sold as Ketodur, exists in some countries and contains 10 or 25 mg ketobemidone.

Pharmacology Experiments on former addicts indicated it was quite addictive and in high doses, compared to other opioids, may have increased abuse potential in former and current opioid addicts. While some effort was first suggested for drafting of a resolution urging governments to stop manufacture and use of ketobemidone, this result was not in agreement with clinical observations, and another study in 1958 did not find it more addictive than morphine. That study noticed that while for morphine the dose for euphoria is the same as that for analgesia, for ketobemidone the analgesic dose was well below the euphoric dose. Thus, even compared to morphine, ketobemidone may be much more effective without causing significant euphoria and thus having a lower risk of addiction under the supervision of a qualified clinician. Ketobemidone is mostly used in the Scandinavian countries, with Denmark topping the statistics. Analgesia after 5-10 mg orally or 5–7.5 mg intravenously lasts 3–5 hours. Ketobemidone is also available in preparations with a spasmolytic, which can improve the analgesia.

Metabolism Ketobemidone is mainly metabolized by conjugation of the phenolic hydroxyl group, and by N-demethylation. Only about 13-24% is excreted unchanged after intravenous administration.

Chemistry Ketobemidone is 1-methyl-4-(3-hydroxyphenyl)-4-propionylpiperidine. It is usually available as the hydrochloride, which is a white powder. It is synthesized by alkylating (3-methoxyphenyl)acetonitrile with bis(2-chloroethyl)methylamine, followed by reaction with ethylmagnesium bromide, and finally O-demethylation with hydrobromic acid. Because of a strong vesicant nature of bis(2-chloroethyl)methylamine there are many other routes developed for obtaining ketobemidone. A route depicted below lays through first alkylating the same (3-methoxyphenyl)acetonitrile with 2-chloro-N,N-dimethylethylamine or 2-chloro-N-benzyl-N-methylethylamine. Next, those amines are alkylated once again using a mixed 1-bromo-2-chloroethane, thus completing the piperidine ring and obtaining a quaternary ammonium salt, which can be dequaternized using thiophenol salt (for N,N-dimethylammonium) or catalytic hydrogenation (for both compounds) to a common 4-(3-methoxyphenyl)-4-cyano-1-methyl-pyperidine. The latter yields ketobemidone after Grignard reaction with ethylmagnesium bromide and ether cleavage.

Illustrations

Worked examples

Example 1 — a first encounter with Ketobemidone

Start with the simplest possible case. Write down what Ketobemidone claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In chemistry, 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 Ketobemidone 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 Ketobemidone 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 Ketobemidone

In research: Ketobemidone appears in chemistry 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 Ketobemidone 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: Ketobemidone is common in secondary-school and first-year university syllabi. It links to neighbouring topics 3-Hydroxyphenyl compounds, 4-Phenylpiperidines, Analgesics, so understanding it makes those chapters shorter.
In everyday life: Look for Ketobemidone 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 Ketobemidone in 20 minutes

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

Frequently asked questions

What is Ketobemidone in simple terms?

Why does Ketobemidone matter?

Because it connects several chemistry 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 Ketobemidone?

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 Ketobemidone.