"Orphines" is a recently coined term for a class of synthetic opioid analgesic drugs, first developed in the 1960s and 1970s by Paul Janssen but categorised as their own distinct grouping by international drug control agencies, such as the EUDA and UNODC in 2025. These have emerged as designer drugs in recent years following increasing legislative controls on earlier families of synthetic opioids such as fentanyls and nitazenes. Orphines are not structural analogues of morphine (known as morphinans), despite the similar name. Initially, the term referred to compounds such as brorphine and bezitramide (which are related to fentanyls, but with the aniline nitrogen cyclised into a benzimidazole ring system), but subsequently a second group of compounds also came to be referred to under this epithet, namely the spiropiperidine derivatives typified by spirochlorphine (R6890), where the 4-position of the piperidine ring is fused to an N-phenyl imidazole ring through a shared carbon atom. Judged by molecular structure these are distinct types, but they show a similar overlay in terms of their three-dimensional shape, and have similar structure-activity relationships and pharmacology. As with many other opioid drugs of this type, replacing the "tail" substitution on the piperidine with a p-fluorobutyrophenone produces antipsychotics instead of opioids (benperidol and spiperone respectively). Other substitutions such as N-phenethyl produce a mixture of both opioid and neuroleptic activity which is generally unsuited for either application, so the compounds with potent opioid activity tend to be those with substituted alpha-methyl benzyl or 3,3-diphenylpropyl chains attached to the piperidine nitrogen, as this favors mu opioid receptor binding but disfavors the antagonist binding at dopamine D2-like receptors which produces antipsychotic activity. A large number of compounds from these two groups are known, but few have been used for legitimate medical applications, aside from bezitramide which was previously sold as a potent, orally acting analgesic in some European countries under the brand name Burgodin, but withdrawn from sale due to a high potential for overdose. More recent research has focused on the development of compounds such as J-113,397 and Ro65-6570, which have low affinity for the mu opioid receptor and instead act as ligands for the non-psychoactive nociceptin receptor.
Table of Orphines
See also List of benzimidazole opioids List of fentanyl analogues Utopioid (drug class)
References
