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Ketobemidone: Wikis


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Systematic (IUPAC) name
CAS number 469-79-4
ATC code N02AB01
PubChem 10101
Chemical data
Formula C 15H21NO2  
Mol. mass 247.333 g/mol
SMILES eMolecules & PubChem
Synonyms Ketobemidone, Cliradon, Cymidon, Ketogan, Ketorax
Pharmacokinetic data
Bioavailability 34% (oral), 44% (rectal)
Metabolism  ?
Half life  ?
Excretion  ?
Therapeutic considerations
Pregnancy cat.  ?
Legal status Schedule I (US)
Routes Oral, rectal, intravenous

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.



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.


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.[1]


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[2] . As a result ketobemidone is mostly used in the Scandinavian countries, with Denmark topping the statistics[3] . This result was not in agreement with clinical observations, and another study in 1958 did not find it more addictive than morphine[4]. 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.

Ketogan novum 5 mg.jpg


  1. ^ Avison AWD, Morrison AL. 303. Synthetic analgesics. Part VI. The synthesis of ketobemidone. Journal of the Chemical Society. 1950, 1469-1471. DOI: 10.1039/JR9500001469
  2. ^ UNODC. "Development of Synthetic Narcotic Drugs". Retrieved 2006-09-07.  
  3. ^ INCB. "Statistical information on narcotic drugs". Retrieved 2006-09-07.  
  4. ^ Bondesson, Ulf (1982). "Biological fate of ketobemidone in man". Abstracts of Uppsala dissertations from the Faculty of Pharmacy 68.  

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