Diethylthiambutene is an opioid

Opioid

An opioid is a psychoactive chemical that works by binding to opioid receptors, which are found principally in the central and peripheral nervous system and the gastrointestinal tract...

 analgesic

Analgesic

An analgesic is any member of the group of drugs used to relieve pain . The word analgesic derives from Greek an- and algos ....

 drug developed in the 1950s which was mainly used as an anesthetic in veterinary medicine and continues, along with the other two thiambutenes dimethylthiambutene

Dimethylthiambutene

Dimethylthiambutene is an opioid analgesic drug, most often used in veterinary medicine in Japan and to a lesser extent in other countries in the region and around the world...

 and ethylmethylthiambutene

Ethylmethylthiambutene

Ethylmethylthiambutene is an opioid analgesic drug from the thiambutene family, around 1.3x the potency of morphine. It is under international control under Schedule I of the UN Single Convention On Narcotic Drugs 1961, presumably due to high abuse potential....

to be used for this purpose, particularly in Japan. It is now under international control under Schedule I of the UN Single Convention On Narcotic Drugs 1961, presumably due to high abuse potential, although little more information is available.