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 imparted by its metabolite norketobemidone. 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. 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. This compound belongs to the class of organic compounds known as phenylpiperidines.

Metabocard for Ketobemidone:
http://www.hmdb.ca/metabolites/HMDB0041913

Ketobemidone

Duration: An opioid analgesic drug that also acts as an NDMA antagonist. Found to be as potent as morphine in physical side effects, and has high potential for addiction like all opioids do. Overdose may lead to respiratory depression/death. Do not mix with CNS depressants or stimulants. Caution should be used for asthmatic users.
Route	Onset	Duration	After Effects
Tripsit Factsheets
Ketobemidone Basic Information: http://drugs.tripsit.me/ketobemidone
Oral:	45-60 minutes	4-8 hours	1-8 hours
Avoid: All other CNS depressants.
Aliases: kbd
Half-life: 2.25-2.45 Hours.
Effects: Euphoria, Dry Mouth, Mood lift, Itchiness, Relaxant, Constipation, Pupil constriction, Analgesia.

Drugs-Forum Ketobemidone Experiences Thread:

• A little kitten thought Keto felt much like Meperidine / Pethidine (Demerol in the U.S.), only slightly longer lasting. He felt the potency is decent, although he doesn't think the 25mg Keto = 60mg Morphine conversion is accurate. He thinks maybe 40-50mg Keto = 60mg Morphine. The kitten also noted that intravenous usage is markedly stronger.. 10mg IV = ~30mg Oral. As he stated earlier, due to the NMDA activity, it feels more like Meperidine/Pethidine or Methadone rather than a standard opioid such as oxycodone or a true opiate like morphine. The kitten thought it was much more sedate than many opiates/opioids but enjoyed it thoroughly. The kitten also recommends a milligram scale. DO NOT EYEBALL THIS SUBSTANCE! It is far too potent to guess how much you are ingesting. The kitten said that his friend, an extremely hot female kitten, experienced a mild overdose due mismeasurement.
  • It's for sure a one of the Holy Grails :) It's famous because that compound have a strong binding to the mu1 and mu2 opioid receptors, that are the ones which create most desirable high and of course addiction (withdrawl could be even worse than that after heroin). It's very interesting cause many countries have used ketobemidone medicaly and very quickly have stopped maufacturing It and It was stopped world wide. Only two countries still have It (as I have read Denmark and Scandinavia, but maybe Sweden too). So It must be something realy good :) Ketobemidone have opinion of the most pleasurable opie when taken IV. On the Scandinavians forums they talk about dosages like 15-20mg, and even 25mg (oral), cause It potency is like morphine, the dosages only for pain relive like for M are 5-10mg. Is it resemble in feeling any other opie or It's more different, rather more especial ?
    • I think there is a common delusion among opiate users, probably based on wishful thinking, that very rare or very new opiates are going to be "the one" - the opiate that finally comes and trumps heroin in terms of high or rush or euphoria. Positive reports of the opiate add fuel to the fire, and opiate users get excited at the possibility of "the one" finally being discovered, but the reports all invariably turn out to be exaggerations, and said opiate always turns out to be a disappointment. Personally I think we should all accept that the opiate that comes along and dethrones heroin will never be found - the molecular structure of heroin in terms of how perfectly its design allows it to cross the BBB means that no opiate will ever give a rush as powerful as heroin or hydromorphone, and the only molecule that could have a stronger affinity for the mu receptor is the native endorphin itself. Its just neurologically impossible for any opiate that already exists or that will be made to have a stronger affinity for the mu receptor than heroin, so it will always remain the most pleasurable opiate. The most enjoyable opiate has been found and it is heroin. Stop searching.

Ketobemidone Experiences Thread:
https://drugs-forum.com/threads/ketobemidone-experiences.128285/

Bluelight Forum Ketobemidone Thread:

• ketobemidone is a prescription opioid in a few countries, it is also reportedly more euphoric than any other opiate does anybody have any information about this drug?
  • 25mg of keto is equal to roughly 60mg of morphine. in studies back in the 50s it was indicated that its more addictive than other opiates. the pain relieving effects can be felt at a much lower dose than the euphoric effects, while with morphine for example, euphoria and pain relief are achieved at the same dose level
    • I have heard of several people on other forums, and on one erowid trip report describing it as being used because it is able to "break through" methadone treatment and still deliver a high probably because of NMDA antagonism. I have also heard that several reports referring to it as the most euphoric opiate because of its intense rush upon administration. However, the current pharmacutical preparations prescribed in sweden use a salt which dramatically reduces bioavailability increasing the required dose, and reducing euphoria. The few people who reported using it prior to the change in preparation that I was able to find described it as the having a greater rush than any other opiate.

Bluelight Forum Ketobemidone Thread (2010):
https://www.bluelight.org/xf/threads/ketobemidone.539761/

Erowid Experience Vault:
https://erowid.org/experiences/subs/exp_Pharms_Ketobemidone.shtml

Germany Federal Institute for Drugs Ketobemidone EU-CSP Core Safety Profile (PDF 5 pages):
https://www.bfarm.de/SharedDocs/Downloads/EN/Drugs/vigilance/PSURs/csp/k-l/ketobemidone-dimethylaminodiphenylbutene.pdf?__blob=publicationFile&v=3

Ketobemidone Hydrochloride Tablets Safety Data Sheet (PDF 6 pages):
https://www.pfizer.com/sites/default/files/products/material_safety_data/PZ00372.pdf

Ketobemidone (Cliradon, Ketogan, Ketodur, Cymidon) is a strong opioid analgesic, structurally related to pethidine, which has been in clinical use for more than 50 years. In the Scandinavian countries ketobemidone is only available in combination with a spasmolytic substance. Ketobemidone has been shown to be a non-competitive N-methyl-D-aspartate (NMDA) receptor antagonist. In spite of a relatively low mu-receptor affinity ketobemidone has a higher analgesic potency than morphine by systemic administration. It is probably due to its higher lipophilicity and consequently more easy penetration into the CNS. Ketobemidone is indicated for the treatment of all types of severe pain, such as postoperative, cancer, kidney stones and fractures.

Ketobemidone:
https://drugs.ncats.io/drug/PQS1L514CF

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. 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.