Ketobemidone

Ketobemidone

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Systematic (IUPAC) name
1-[4-(3-hydroxyphenyl)-1-methyl-4-piperidyl]propan-1-one
Clinical data
Routes of administration	Oral, rectal, intravenous
Legal status
Legal status	US: Schedule I
Pharmacokinetic data
Bioavailability	34% (oral), 44% (rectal)
Identifiers
CAS Number	469-79-4
ATC code	N02AB01 (WHO)
PubChem	CID 10101
Synonyms	Ketobemidone, Cliradon, Cymidon, Ketogan, Ketorax
Chemical data
Formula	C15H21NO2
Molar mass	247.333 g/mol[[]]

Ketobemidone (Cliradon, Ketogan, Ketodur, Cymidon, Ketorax, &c.) is a powerful opioid analgesic. Its effectiveness against pain is in the same range as morphine, and it also has some NMDA-antagonist properties. This makes it useful for some types of pain that don't respond well to other opioids. The most commonly cited equalisation ratio for analgesic doses is 25 mg of ketobemidone hydrobromide to 60 mg of morphine hydrochloride or sulfate and circa 8 mg of ketobemidone by injection.

It is used for all types of severe pain, such as postoperative, cancer, kidney stones and fractures.

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 man was published in 1946, and it was introduced in clinical medicine shortly after.

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 ethylmagnesiumbromide, and finally O-demethylation with hydrobromic acid.

Pharmacology

Experiments on former addicts indicated it was more addictive than other opioids, so in 1954 the Economic and Social Council took a resolution urging governments to stop manufacture and use of ketobemidone . As a result ketobemidone is mostly used in the Scandinavian countries, with Denmark topping the statistics . 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.

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.

Ketobemidone is mainly metabolised by conjugation of the phenolic hydroxyl group, and by N-desmethylation. Only about 16% is excreted unchanged.

Pfizer manufactures ketobemidone under the tradenames Ketogan and Ketorax. It is available as tablets, suppositories and injection fluid. A sustained release formulation exists sold as Ketodur in some countries containing 10 or 25 mg ketobemidone.

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References

da:Ketogan