Dihydroetorphine was developed by K. W. Bentley at McFarlan-Smith in the 1960s and is a potent analgesic drug (painkiller), which is used mainly in China. It is a derivative of the more well-known opioid etorphine, which is used as a very potent veterinary painkiller and anesthetic medication, primarily for the sedation of large animals such as elephants, giraffes and rhinos.
Dihydroetorphine is a semi-synthetic opioid, used mainly as a strong painkiller for humans. It is several thousand times stronger than morphine (between 1000x and 12000x more potent depending what method is used for comparison), although it is poorly absorbed when taken orally. Sublingual forms of dihydroetorphine are used in China at doses ranging from 20 to 40µg repeated every 3-4 hours, and are reported to cause strong analgesia and relatively mild side effects compared to other opioids, although all the usual opioid side effects such as dizziness, sedation, nausea, constipation, and respiratory depression can occur. Transdermal patches of dihydroetorphine have also been developed.
Dihydroetorphine is considered to be somewhat less addictive than many other opioids, and is also sometimes used in China as a substitute maintenance drug for opioid addicts, in a similar way to how the related drug buprenorphine is used in western nations.